hckrnws

I think it's neat that this summary is written by an author of the scientific manuscript. Oversimplification is a risk, but this approach eliminates the possibility that the writer did not understand the underlying science.

Yea, and it was a great read too. I wish more researchers would publish blog posts alongside their technical whitepapers, although I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.

(I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was.)

Communication skills are often missing in engineering too, but I think I'd argue they should be required - all work is fundamentally collaborative.

Being able to effectively communicate to different people on your team, outside your team, managers, business people, etc is not optional and more than once I've seen things get stalled or turn into a mess because communication didn't happen.

STEM is often a haven for neurodivergence but I think communication skills are something that is largely learned and not something that comes naturally for everyone. People who are good at communicating spend a fair amount of effort rewriting, trying different wordings, different introductions, getting feedback from people, etc.

FWIW I see things like being able to sell a proposal, managing expenses, planning, etc as optional - these are good to have, but someone else can do them if you can communicate well, but in the end the only person who can communicate what you're thinking is you.

"Required" is a bit of a gatekeeper, while I agree good communication skills are valuable.

Blog form content in particular, _requires_ proofing, re-editing, and so on and there's a whole skill set which contributes to makes such content sticky and engaging.

You also seem to be confounding your own point. Indeed all work is collaborative, someone who lacks communication skills, will generally team up with other collaborators who can bring those skills to bear.

I think the benefits greatly outweigh any dangers. I far prefer to read something like this than something written up by a journalist.

> I acknowledge that not everyone involved in science has or wishes to acquire the skills needed to write blog-form content.

They should. If your research is publicly funded you should make it as available to be public as possible. Academics should be able to communicate, and I very much doubt they are unable to acquire the skills

> I'd also be worried about a world where researchers are evaluated based on the virality of their blog posts, vs. how impactful their work was

Given how bad the measures of impact and the distorted incentives this produces I am not even sure this would even be a bad thing.

If nothing else it improves transparency about what they are doing, again with public money.

>They should. If your research is publicly funded you should make it as available to be public as possible. Academics should be able to communicate, and I very much doubt they are unable to acquire the skills

So in addition to being:

-professional researchers

-professional teachers

-professional project managers

-professional budget specialists

-professional scientific writers

-a failed idea away from losing it all

They should also become:

-professional PR managers

-professional popular writers

While still being paid (poorly) for a single job of all of these.

We have similar demands for folks in other professions. I know software engineers who are still coding day to day who also have to manage team budgets and track hours/projects, write patents, write blog posts to make the company look good, mentor juniors, sometimes teach internally or even to external audiences, present at conferences, etc.

They should not being doing a lot your first list, and should have specialist help available for some of the rest.

I am not suggesting they become PR managers, and the writing skills I am suggesting they acquire is simply that required to do things like blogging. I am not suggesting they achieve the standards a professional writer would have, just the ability to write clearly and make the effort to do so.

Academics should be highly skilled people.

In fact a lot of the problem is not they cannot do it, but of distribution. A lot of universities to have academic blogs and subsites about departments and individuals research. Its not anything like as visible as the journalists write ups about it

Yes, in a perfect world there would be professionals doing this instead of putting it all on the academic.

However, we live in an imperfect world. When people say "should" in these contexts, they're not describing some ideal way the world works. They're prescribing actions that are realistic based on the current system we live in.

The world sucks. It's more useful to work with the small amount of control one has, than to do nothing because the action doesn't solve a wider systemic problem.

yes

> They should. If your research is publicly funded you should make it as available to be public as possible.

The public can access it by becoming subject matter experts. If the government or the public to which it is responsible requires a popsci treatment they can pay other people with this skill set.

I don't doubt having this skill set is useful I merely disclaim any sort of obligation on the part of the scientific staff to possess or exercise such a skill.

A few years ago, at least in my field, there was definitely a trend of people at least doing twitter threads explaining the key findings of their papers. It's obviously less in-depth than a blog post would be, but it was still usually a far more accessible version of the key ideas. Unfortunately, this community has basically dissolved in the last few years due to the changes in twitter and to my knowledge hasn't really converged on a new home.

[flagged]

It's a controversial observation, but it is very true. I work with AI models and have to read recently published research to work with the latest developments in the field.

Do a quick keyword search on papers related to the subject. So much of it is completely useless. It is clearly written to keep people busy, earn credentials, boost credibility. Papers on the most superfluous and tangential subjects just to have a paper to publish.

Very little of it is actually working with the meat of the matter: The core logic and mathematics. It is trend following and busywork. Your sentiment is controversial because people are religiously loyal to the intellectual authorities of these credentialed systems, but a lot of published research does not push any boundaries or discover anything new. This paper seems to be an exception.

I would argue that a lot of the research published in the social sciences also falls under this category. It is there so that someone has a job. I'm not discrediting social sciences in general, am just pointing out that there is a lot of ways to creatively take advantage of academia to secure a paycheck and this is certainly exploited. The kneejerk reaction to reasonable criticism just proves this point even further.

This is a good thing. This is where the economy surplus went. Not to 5 days of leisure for everyone. But to jobs that keep us occupied, engaged, and motivated but aren't strictly required. The alternative is just either starving everyone to death, except for a few elite and their slaves, or everyone being bored out of their minds and wondering what the point of life is.

If the solution is ever more manuscripts that solve no interesting problems and that nobody will ever read, let's find another solution.

Why would you assume someone would write the paper at all, if the problem was uninteresting?

That's literally the basis of employment. People write papers, they get paid. Science does not get done.

The funding for scientific projects comes from applying for grants from the government. Researchers must write proposals to demonstrate the value of their projects. After the project is completed, they are also required to submit a final report to verify that the project was indeed carried out as approved by the supervising authority.

For one thing, because I watch the AI and ML categories on arxiv.org.

Is this a joke or so wildly out of touch? Both of your alternatives sounds very much like the world today, but we’re all still working anyways

Can you cite your sources please?

Sabine Hossenfelder has a few comments on this topic in her YT channel.

Hossenfelder feels like a fraud. She likely is.

Sabine Hossenfelder cast herself out from academia and took a recent turn to monetizing laundering peoples vague understanding string theory is a waste of time (cannot be proven empirically) into academia is doing fake work and if they'd apologize and own up to it, maybe we would trust them again.

Most famously, through a bizarrely written letter from an anonymous whistleblower pleading that she not topple the academy, as it would ruin the lives of thousands of academics making up things to get grant money to survive.

I can't parse either of your sentences. Maybe you could introduce some intermediate variables, or use parentheses to give them structure?

I can't parse what you're asking for :|

Ran my comment + your reply through AI and asked it to respond to you, as I do want to help. Let me know if there's other instructions I can give it, it may have taken your variable ask too literally? :(

Here's its output:

Sabine Hossenfelder, after distancing herself from academia, has recently pivoted to monetizing a specific narrative: Let’s define Premise A as “String theory is a waste of time because it cannot be empirically proven.”

She generalizes from Premise A to a broader Claim B: “Academia, more broadly, is producing fake work.”

Her argument seems to imply that:

If academia were to publicly acknowledge this, or apologize for promoting unverifiable theories, then the public might begin to trust it again.

This general thrust reached a kind of crescendo in one of her more notorious moments: — An oddly written letter, allegedly from a whistleblower within academia, essentially begging her not to “bring down the system.” The letter’s rationale? That dismantling the status quo would destroy the livelihoods of thousands of academics who, according to the letter, are fabricating just enough plausible-sounding work to secure grants and stay afloat.

Pretty valuable to have people who see A to be true, have presumably seen some of B to be true too (trivial to see with the many replication crises) - and then to do their best to disseminate that to the general public so change can be made. I see no problem there, and I'd hate for the case where people were afraid to make content covering it because they were waiting for years for huge studies (which could also be poorly done) to 'prove' it.

Yeah, you see that's 100% not a citation, and shows why we need academia...

Sabine is an asshole. Doesn't mean she is wrong, and I appreciate when she reads some paper that has made a bunch of headlines to figure out if they're full of crap or not (spoiler alert: the answer is usually yes), but while she can identify the problem she's not part of the solution. Her divorce from academia means she has little power to affect change for the better given how the incentives are currently aligned. She can make a lot of noise, but the people actually pulling the levers have rigged the system in their favor enough to not care.

So she is an arsehole for exposing bullshit? I don't see the problem. I think people take issue with her because of her confrontational persona.

>while she can identify the problem she's not part of the solution

Does she have to be, in principle?

> Her divorce from academia means she has little power to affect change for the better given how the incentives are currently aligned.

Wouldn't be so sure about that. She is getting more public exposure than most academic would in their lifetime. More importantly, exposure to audience _outside_ of academia. Voters. Her effort in creating public awareness has certainly stirred the nest in some academic circles.

There have been countless academics who have discussed this topic, occasionally not behind closed doors. Regardless, it’s certainly my observation as well.

Countless academics have leveled targeted criticisms at various practices and gone on to back those up. They are targeted, actionable objections; not vague blanket dismissals.

Most jobs are really not important either, they just keep people busy. Do you need sources for this claim, too?

Yes. Who are these people paying for jobs that don't do anything, and why are they more concerned about "keeping people busy" than their own profits?

I’m not the one you were referring to, but I have similar experiences. I’m living in Germany, and most bigger companies here have such issues. I also worked for companies in Netherlands and Island, so I assume it’s an European, if not global problem. No one is concerned about keeping people busy. It’s a systemic problem. And there are multiple reasons for it. One reason is that the bigger a company grows, the more hierarchy is necessary. But increasing hierarchy will lead to people doing the work are not the people that are most responsible for it. So we have people that should do the work but they aren’t too motivated because they are not responsible enough - they are too low in hierarchy level. And we have people that are responsible but don’t do the work. They delegate. If something goes wrong or takes too long, they will have enough time and skill to find an excuse. Another issue is that you need more people to get specific things done. At some point in time these things have been done, and you actually don’t need the amount of people anymore. But you can’t quit them because of worker’s laws. You maybe even don’t want to quit them because you think you still need them. People, of course, tend to find reasons why their own work is important. And they will communicate that. And the chance is good you’ll believe that and don’t question it enough. There are more reasons for that. But it’s a fact that in many, many companies the economical results of a lot of employees is almost zero. If you don’t believe this, just google the biggest companies in Germany, pick one, apply for an office job and start to work there. It won’t take a month until you’ll find out. Btw. I don’t want to criticize the situation too much. Probably it’s good that people are employed, even if they don’t work efficiently. Otherwise the unemployment rate would be much higher. Then again, Germany‘s economy is flatlining and a crash is not unlikely.

Sounds like you're describing the principal-agent problem. https://en.wikipedia.org/wiki/Principal–agent_problem

> But you can’t quit them because of worker’s laws

This is generally not a problem in the US.

It's like saying "if you know half of your advertising dollars are wasted, why don't you just cut your ad buy in half?"

I still remember the joke from my first job:

Q: How many people work at this office?

A: About half.

An apt analogy. Circling back to scientific research, I'm sure an investigator would be more than happy not to spend the time, effort, and grant money on a project that wasn't going to produce worthwhile results. If only we could know in advance without doing the work.

That does not, of course, mean that "most research being produced isn't really research, just people keeping busy" or whatever other nonsense an uninformed outsider feels like spewing.

Most people involved like hiring more people.

Workers generally like jobs where the workload is low. Managers gain status by having bigger teams, whether they need the extra people or not. Even investors often prefer hiring (a sign of growth) to layoffs, and executives are mostly concerned with pleasing investors.

Even well run tech companies with money to burn hired more people than they needed.

Companies can lay off thousands of employees and not have it affect growth, profits or, really, the workload of remaining employees. How could that be possible if everyone's work is so crucial?

Everyone (eh, most) believes their work is crucial.

There are cognitive biases like the self-serving bias, or the IKEA effect, which leads individuals to overvalue their own contributions, as well as subjective importance derived from their immediate impact and daily responsibilities. And of course limited visibility into the broader organizational priorities often obscures how different roles contribute to overall growth and success.

The people doing the hiring are typically not the people concerned about profits at medium and large sized companies. Sure someone has to approve the headcount numbers, but realistically this is an extremely flawed process.

[dead]

Why do you think profits are important?

I would think that profits are important to investors, since that's why they invest in the first place. Maybe not though.

The original claim was "Most jobs are really not important either, they just keep people busy." Causing numbers to change on a balance sheet is not important, unless that corresponds to actual worthwhile work – in which case, the worthwhile work is what matters, and the balance sheet is just an artefact of accounting for it.

Ever since I first read this theory, I have always been wondering how credible is this. Where have you heard it from ?

I am not sure, but probably related: https://evonomics.com/why-capitalism-creates-pointless-jobs-....

The Bullshit Jobs jobs theory has been widely discredited by researchers, but you probably won't believe them. Consider that most business is B2B so it makes sense that the casual observer would not know what it's for. Additionally, the Bullshit Jobs book relies on a magazine survey, actual studies shows that the percent of people who consider their jobs meaningless is very low and also decreasing over time

> the percent of people who consider their jobs meaningless

Worth to point out that there is a huge difference between people considering their jobs meaningless AND their job being meaningless, though.

No, but it's a core part of the Bullshit Jobs theory, that the jobs are obviously bullshit to everyone involved. I would suggest that most jobs that aren't particularly valuable are probably not locally recognised as such (i.e. by the person or by their manager).

(In general I think while plenty of people are familiar with varying levels of pointless effort in their jobs, it's rare that a whole job consists of that, at least as far as the person doing it and the person hiring for it are concerned)

I think you're right, but it's not how I remember it for some reason.

I didn't read the book "Bullshit Jobs" [1] as an attempt to quantify how many jobs were bullshit. The author was an anthropologist with no interest in quantifying the economic impact. It's lots of amusing anecdotes from frustrated workers and a nudge for people to question the efficiency of capitalism.

At least that's how I read it. But reading the wikipedia page it sounds like a lot of people fixated on the idea that society could double its efficiency. Hard to know if there's a correct interpretation of the book's claims, and unfortunately we can't ask: the author David Graeber died in 2020.

[1]: https://en.wikipedia.org/wiki/Bullshit_Jobs

> while he claims that 50% of jobs are useless, less than 20% of workers feel that way, and those who feel their jobs are useless do not correlate with whether their job is useless. (Garbage collectors, janitors, and other essential workers more often felt like their jobs were useless than people in jobs classified by Graeber as useless.)

Well, again, there is a huge difference between one's own perception of their job being useful or not. I believe garbage collectors, janitors, and nurses, are not examples of useless jobs. Useless jobs are mainly in the office, called "paper pushers". I mean come on, have you not been to any jobs (nor heard of any) where you had to pretend you were busy just to get paid? I saw plenty of cases.

>The Bullshit Jobs jobs theory has been widely discredited by researchers, but you probably won't believe them. Consider that most business is B2B so it makes sense that the casual observer would not know what it's for.

I'm not sure how it's possible that anyone over the age of 30 can say something like this with a straight face. Have you ever worked anywhere? I'd love to know how the "researchers" have discredited this. I'd also love to see their other papers (likely, also, bullshit).

There used to be a common practice of scientists writing summaries of their research for lay people. I think they viewed it as their civic duty. I had a collection called the World of Physics which included essays written by various scientists. I originally had it in the 90s and found it again after many decades. Would highly recommend.

https://www.amazon.com/World-Physics-Library-Literature-Anti...

It's far preferable to having university PR people write some hype piece. Where they'd spend the whole time gushing about it being a world first, paradigm shifting, blah blah blah, the author focuses on things that actually matter. e.g. Is it testable? Yes, here's what to look for.

Yeah, wow. That was great. His solution seems so simple and clears all the previous model's problems. I guess every black hole could contain its own universe.

Too bad the author didn’t explain more the concept of the “parent” universe and how our own (contracting & expanding) universe got created. Nice things to read/consider/ponder late at night :-)

Unfortunately, it appears that the universe does not care very much about human satisfaction. Fortunately, other humans do.

What makes you say that? This feels like a very convenient planet.

I would be surprised if the size doesn't matter in this case. On the one hand, tiny black holes tend to be rather short-lived. On the other, I suppose some threshold mass/energy is needed to generate a child universe that doesn't collapse immediately.

Ironically that was basically the first thought many had when it was clear we cannot explain what happens in the edge case of a singularity. It was always "perhaps another unsiverse or a way into a parallel one".

It still leaves a lot of questions though, especially if you try to marry quantum mechanics to these makroscopic models. Where did the initial black hole come from and should a corresponsing anti matter black hole exist?

Well that's an indsight bias if I've seen one. This is the first time I ever read that the "bottom" of a black hole could be a entirely new universe. If there ever "always was" a common hypothesis, it was the wormhole.

There wasn't much substance to it back then, but the idea certainly had been circulated in context of singularities where physics break down. So hypothesis is probably an exaggeration.

The article is based on a physics paper (arXiv:2505.23877), not management theory or institutional metaphors.

What the paper actually proposes is that the Big Bang may have been a gravitational bounce inside a black hole formed in a higher-dimensional parent universe. Quantum degeneracy pressure stops the collapse before a singularity forms. From the outside, it looks like a black hole. From the inside, it evolves as a 13.8 billion year expansion. That is general relativity applied across frames.

Simply put this is a relativistic collapse model with quantum corrections that avoids singularities and produces testable predictions, including small negative curvature and a natural inflation-like phase.

>in a higher-dimensional parent universe

That's incorrect: The parent universe is not higher-dimensional, it's the same good old 3+1 as our universe.

What they propose is: Let's take our good old GR, and start with a (large, dilute) compactly supported spherically collapsing collapsing cloud of matter. During that, you get an event horizon; afterwards, this looks like a normal black hole outside, and you never see the internal evolution again ("frozen star", it's an event horizon). Inside, you have the matter cloud, then a large shell of vacuum, then the event horizon.

Quantum mechanics suggests that degeneracy pressure gives you an equation of state that looks like "dilute = dust" first, and at some point "oh no, incompressible".

They figure out that under various assumptions (and I think approximations), they get a solution where the inside bounces due to the degeneracy pressure. Viewed from inside, they identify that there should be an apparent cosmological constant, with the cosmological horizon somehow (?) corresponding to the BH horizon as viewed from the outside.

All along the article, they plug in various rough numbers, and they claim that our observed universe (with its scale, mass, age, apparent cosmological constant, etc) is compatible with this mechanism, even hand-waving at pertubations and CMB an-isotropies.

This would be super cool if it worked!

But I'm not convinced that the model truly works (internally) yet, too much hand-waving. And the matching to our real observed universe is also not yet convincing (to me). That being said, I'm out of the cosmology game for some years, and I'm a mathematician, not a physicist, so take my view with a generous helping of salt.

(I'm commenting from "reading" the arxiv preprint, but from not following all computations and references)

PS. I think that they also don't comment on stability near the bounce. But I think that regime is known to have BKL-style anisotropic instability. Now it may be that with the right parameters, the bounce occurs before these can rear their heads, and it might even be that I missed that they or one of their references argue that this is the case if you plug in numbers matched to our observed universe.

But the model would still be amazing if it all worked out, even if it was unstable.

> with the cosmological horizon somehow (?) corresponding to the BH horizon as viewed from the outside.

That’s not mentioned in the summary. After inflation the event horizon would not exist.

I have not really looked at the summary, opted to go straight to the source.

This identification happens in equations 31-34 on page 7f subsection "Cosmic Acceleration" in https://arxiv.org/abs/2505.23877

The justification looks super sketchy and hand-wavy to me, though, which I summarized as "somehow (?)".

"After inflation the event horizon would not exist."

Apparent cosmological constant viewed from the bouncing inside induces a cosmological horizon, which they identify with the black hole horizon viewed from the outside. Super elegant idea, but I don't buy that this is supposed to be true.

Why does this black hole bounce whilst others from the limited info we possess appear to be stable regardless of lack of singularity

The bounce is invisible from the outside -- an event horizon means causal decoupling. From outside, the formation of the black hole looks like the good old "frozen star" picture.

There will never be observational evidence on what happens on the other side of any event horizon, you'd have to cross over to the other side to see it for yourself (but you won't be able to report back your findings). There's a fun greg egan short story about that ;)

What's the story?

"The Planck dive", freely available on Greg Egan's website https://www.gregegan.net/PLANCK/Complete/Planck.html

> What the paper actually proposes [...]

(Emphasis mine)

I haven't read the paper yet, but this sounds like a (good) summary of exactly what the article is saying. It makes me wonder what, if anything, you feel is different from the way you put it and the way it is explained in the article? As a layman they seem the same to me.

The article was written by the main author of the paper, so yes, it's a good summary :)

I meant that the parent comment to mine was a good summary of the article.

However, the comment was worded as if it meant to highlight some difference between how the article summarized the paper and what the paper is actually saying. Since I couldn't see a difference between the above poster's summary and that in the article, I was curious what I was missing.

Looking at the paper, I don't see any higher dimensions of the parent universe, it is still using the same 4D General relativity framework for the parent.

So, could the same interaction create planar universes inside our own black holes? Linear universes inside those as well?

It's incredible how big a 4-D universe would have to be to contain our own, even crazier if there are more levels; but our own universe could contain easily uncountable planar universes.

Isn't it more a matter of how space is folded in higher dimensions rather than an increase in volume that accounts for containment? There is plenty of space in the corners:

[0]: https://observablehq.com/@tophtucker/theres-plenty-of-room-i...

Sigh: https://arxiv.org/abs/2505.23877

They have basically disproved Penrose-Hawking's theories of singularity? Isn't that like a pretty big deal? To people working in this field, what is the reaction to this paper?

They predict a non flat curvature, so no (not with existing data and measures, which may improve in the future).

Could you elaborate for a layman? Is there more to the following statements than it seems?

> Penrose proved that under very general conditions, gravitational collapse must lead to a singularity..... we show that gravitational collapse does not have to end in a singularity. We find an exact analytical solution – a mathematical result with no approximations

seems like this is just giving up on quantum gravity and saying the pauli exclusion principle will hold regardless of the gravitational force.

You mean small positive curvature.

If the crux of the article is the fermion bounce, and you compare that to how much matter and energy we are aware of, that is quite the black hole, which leads one to start wondering what environment it existed in to become that size. Even if it is now stuck due to a positive curvature of just bouncing back and forth.

I would like the article to acknowledge a bit more though that blackhole universe theories and speculation are quite old now, not radical and a striking alternative, as it is natural to think about it once you learn of the concept of event horizons. What differentiates this though is the analytical solution.

I have two problems / questions with this:

1. This theory requires a parent universe that can't have been formed inside a black hole. This means there must a be second "universe creation" mechanism that we can / may never know about from our child universe. For me, this doesn't really answer the true question: "How did our universe begin?" Yeah, it may the "unknown field with strange properties" but instead we get an unknown parent universe with strange properties.

2. The black hole in the parent universe must be much much bigger than anything we see in ours since it has to contain all the matter that we see. How is a black hole supposed to form that is 750 billion times bigger than the largest black hole we know about?

I don't see this idea as very new.

There are many models of black holes, such as the Schwarzchild solution, that have an area of "asymptotically flat spacetime" which is, from the viewpoint of our universe, part of the black hole. That something happens around the singularity that creates this new universe doesn't sound that crazy.

If our universe is a child of another universe and that is a child of another universe and so forth it fits into the kind of "multiverse" model that addresses issues such as "why does the universe have the parameters it does?" Either there are a huge amount of universes such that we're lucky to be in one we can live in, or there is some kind of natural selection such that universes that create more black holes have more children.

As for the relative size of the parent black hole, conservation of energy doesn't have to hold for universes in the normal sense. One idea is that the gravitational binding energy of the universe is equal to the opposite of all the mass in the universe such that it all adds up to zero so we could have more or less of it without violating anything.

Do you find the idea of an infinite regress -- "our universe is a child of another universe and that is a child of another universe and so forth" -- holds much explanatory power for you?

To me it's prima facie a hollow explanation. I get that some models, like eternal inflation or certain cyclic cosmologies, entertain the idea of an infinite past or blur the standard arrow of time... but how does pushing the origin question back indefinitely actually resolve anything?

The problem is that:

- We have a parent universe we will never be able to observe.

could be a true statement.

The "infinite sequence" part is just a likely implication, it isn't necessarily true. We would need information we can't access to find out.

I doubt you understand what science is about. The proposed theory, like any theory, should be judged on its power of prediction and simplicity. It doesn't matter if it doesn't satisfy your curiosity.

where is the "prediction and simplicity" part in this theory?

Well said

> "why does the universe have the parameters it does?"

To those who say "oh but if this parameter was slightly off, that thing I subjectively decided to pick wouldn't have happened!":

How would you know that this universe could exist in any other way? Wouldn't things just stabilize into certain frequencies and lengths after some time?

To me "fine tuning" isn't really a conundrum, it is just question begging and you don't need to wish it away with multiverses.

> we're lucky to be in one we can live in

Nitpick: We couldn't be anywhere else, except nonexistent.

The anthropic principle

  > requires a parent universe

Does that repeat forever? Does it lose energy in the bounce? If so, to where and how?

  > The black hole in the parent universe must be much much bigger than anything we see in ours

Most importantly, you don't need everything all figured out at once to publish. Then no one would always publish. There'd be nothing to improve on. Only one publication that says everything. Till then, everything does have criticisms and is incomplete. It's good to have criticisms! They lead you to the next work!

>> The black hole in the parent universe must be much much bigger than >> anything we see in ours

>> Yes and no. You're not thinking about contraction. With relativity >> we can fit a 100ft ladder inside a 10ft barn.

I believe the OP was talking about mass, not linear dimension. (And if he wasn't, I am.) Unless somehow mass inside a black hole is not constant? (ignoring accretion)

Relativity applies to mass too. Accelerate and you become heavier.

Remember, mathematically, a blackhole is mass in an infinitely small point. You are dividing by 0. I don't know the answer, but if someone is saying that from the outside the apparent mass is different than from the inside, that doesn't set off any alarm bells. We literally are talking about Dr Who style "it's bigger on the inside". Even the ladder example should make you think about mass. Without relativistic effects the mass inside the barn is only part of the ladder. With relativity, the whole ladder, and thus mass, is inside. So yeah, weird things happen.

*aparent mass goes up

Things don't get more mass, they just take more energy to accelerate which looks a lot like more mass.

It doesn't imply for example, a high speed mass would cause more gravitational attraction than a slow one.

If that was the case, a black hole would be even worse as it accelerates matter towards itself and it gains "bonus mass"

Black holes have the same mass and information as the stars that formed them.

Unless the theory also breaks mass and information conservation, the star that gave birth to our black hole must have been as massive as our entire universe.

I doubt we have any theory how a star that size can have formed.

I meant apparent mass. Just dropped the apparent because we're on HN and anyone familiar with relativity is likely going to know what I mean. I mean if actual mass went up we'd be violating conservation of energy. It's all about your frame of reference and you can treat these things as local systems.

Where does the information of the previous universe before the bounce go? Is it destroyed?

It's been suggested it is gone and that perhaps even new laws of physics are created with each iteration (but I don't know why that would be).

Cosmic Background Radiation distribution could be that information. The distribution of mass hitting the event horizon then bouncing

Maybe we live inside an universal hash function.

1. It is possible that every universe is formed in a blackhole – an infinite universe-blackhole-universe chain. We don’t know what “infinity” means in this scenario, so we can’t simply rule it out. For comparison, Aristotle ruled out an infinite chain of causes, which we now know (with the help of hindsight, of course) is a flawed conclusion.

2. We don’t know whether our universe is big or small compared with other universes. We don’t know whether, or how, it makes sense to compare sizes between universes.

Big Bang is arguably the biggest speculation in modern science.

The outer universe could have always existed, but unlike ours it eventually collapsed. By contrast ours did the reverse, and it looks like it will expand forever. There is a neat symmetry. I guess you could make the case that it’s really just one universe, and the collapse and expansion mirror each other.

We think the universe had to "begin" because we "began" and tend to anthropomorphize. Is that necessarily true? The universe is under no obligation to have a beginning. Sail around the Earth and you might just end up right where you started.

Current observations make it likely that our observable universe expands (think "stretches"), and the expansion will continue forever.

If it's expanding, then it was smaller earlier. Asking about the far past is a natural reaction, and the Big Bang theory is a pretty good attempt at explaining that.

https://en.wikipedia.org/wiki/Expansion_of_the_universe

https://en.wikipedia.org/wiki/Chronology_of_the_universe

The Sun had to begin. At one point it was just accreting gasses, then at some point gained enough mass to ignite. People also start at some point they begin as a daughter and grow eventually into a viable life. But also our galaxies had to form before our sun. So, yes there are beginnings to things. At one point they weren’t, at another point they were.

Yes, but earth still had a beginning.

I agree with you, though - causal explanations are compelling and confer a sense of certainty and humans seem to like that, but it doesn't make them necessary.

Your first statement right off the bat is a bit of an assumption, why can’t the parent universe also have been formed inside a black hole? Why did you assume that?

Wouldn't every theory/model of the universe leave room for follow up questions? Why is it problematic if it doesn't answer literally every conceivable quandary?

It's black holes all the way down!

I've read somewhere an article which posited that our 3D universe might be inside a 4D black hole. When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom. Movement is still possible in the tangential directions however, so what you get is basically an N-1 dimensional universe. So maybe our 3D universe is actually matter that fell into a 4D black hole, and our 3D black holes contain 2D flatland universes. And of course, the outer 4D universe might be in a 5D black hole, etc.

Yes, and then there's the parlor game of guessing what familiar property of our known universe is actually a spaghetified fourth dimension.

I guessed c once. It would be a constant. Maybe all the constants are spaghettified remains of a superior universe.

I don't think c is a good candidate, because it's not really a parameter. It's just a correction factor for our mis-judgment in picking different units for time and space.

In "natural units", we define the units so that the important conversion factors (c, G, h-bar, etc) work out to exactly 1. You can say that c is one light-year per year and then forget about it.

The true parameters of the universe are the dimensionless constants: the fine structure constant, proton-electron mass ratio, 3+1 dimensions, etc.

> I don't think c is a good candidate, because it's not really a parameter.

dont be so sure! there is no way to experimentally know if c is a parameter or not. there are consistent physics formulations which have variable, even anisotropic c. physicists dont usually explore them (e.g. tangherlini relativity) though because the math is considerably harder.

Physicists (and in particular the subset doing physical cosmology) don't usually explore parametrizations of c because they're not clearly physical (and sometimes even clearly unphysical), or alternatively don't help solve astrophysical or cosmological problems.

Relativists sometimes like to explore things that make using the Tangherlini transformations rather than the Lorentz transformations look positively benign. (To be clear, the Tangherlini synchronization system is clearly unphysical, requiring infinite speeds. His thesis also proposed using a distinguished global frame, which is not really philosophically different from how the standard cosmological frame is used, and seems OK because the distribution of stress-energy can pick out useful systems of coordinates in standard relativity. Unfortunately his method frustrates and probably outright breaks comparisons between inertial reference frames related by a boost, which the standard cosmology does not, and it's hard to see an alternative method that preserves his central ideas.)

But why even be stuck with 3+1d spacetime like Tangherlini? He was trying to do physics. But an unphysical metric signature with 47 plusses and no minuses is really cool!

In our observed universe, FAPP, c is the same everywhere after recombination, and we get that from spectral lines. You have to play really weird games to preserve the Lyman-alpha forest's apparent isotropy while introducing spacetime (or redshift-space, here) anisotropy. Things like BAOs make the problem even harder.

If we strip away all that pesky radiation and the information its structure encodes, analysing variations of c gets a lot easier. A relatively recent paper (Lewis & Barnes 2021) I enjoyed considered anisotropy in the one-way speed of light in an FLRW cosmology with zero energy density (well, really the convenient Milne model, which is also far from spatially flat). "So far, we have considered two cases, where either the speed of light is isotropic, or the extreme case where the anisotropic speed is 1/2 in one direction, and infinite in the other. The question remains whether this holds true in general case, for an arbitrary κ": https://www.cambridge.org/core/journals/publications-of-the-... (arxiv: <https://arxiv.org/abs/2012.12037>). "For more general cosmological models, where the presence of mass and energy results in curved space-time, the picture is more complicated as there is no simple mapping of the modified Lorentz transformations into the general relativistic picture. We leave this discussion for a future contribution."

Sadly there doesn't seem to be a future contribution yet, at least going by published citations (<https://scholar.google.com/scholar?cites=2012575105829699847...>). (Of those, I've put the Chamberlain paper on my to-read pile; you'd appreciate how it relates to Tangherlini, "credence is given to one-way infinite light-speed inward to each particle in direct comparison against Einstein’s isotropic (c=constant) light-speed").

Of course there's also the excellent Magueigo 2003 VSL overview <https://iopscience.iop.org/article/10.1088/0034-4885/66/11/R...> copy <https://cds.cern.ch/record/618057/files/0305457.pdf> preprint <https://arxiv.org/abs/astro-ph/0305457>.

And even if you can make sense of an f(c) cosmology in the early visible universe, you will get to epochs before recombination and try to make sense of the later universe's chemistry, which of course relates to big bang light nucleosynthesis, baryogenesis and electroweak ssb. How do you abolish Lorentz symmetry in those epochs? Good luck!

(I mean, I think if you are doing physical cosmology you ought not to ignore gauge theory...)

my understanding is vsl physics can eliminate singularities if you have c approach zero in the presence of mass in a flat spacetime. AIUI this is equivalent to einsteinian curved spacetime except as you approach zero and deviate from linear in your c(m) formula.

you get pseudo black holes but depending on the extremeness of the deviation from linear, the difference to black holes might not be observable with current tech.

Not sure what you mean; you can't have any mass in a flat spacetime and obey the Einstein Field Equations for a Lorentzian spacetime (because T_{\mu\nu} doesn't vanish everywhere).

There are a variety of types of variable speed of light. If we foliate to 3+1 the usual picture is that c is constant on all spatial slices. Some VSL theories have the same c at all points on a given slice, but introduce a time variation of c. Other VSL theories introduce spatial variation as well (or instead). These families of theories all have significantly different equations of motion or actions from one another (cf. <https://en.wikipedia.org/wiki/Einstein%E2%80%93Hilbert_actio...>). There's no obvious reason why c couldn't relate in a more complicated way to the stress-energy tensor than the Einstein gravitational constant does, but there's also no obvious reason to think such an alternative theory should produce free-fall trajectories similar to those from GR.

In any case, I think you have to choose your function on c, obtain the field equations, decide which energy conditions and constraint equations you want to impose, set appropriate boundary conditions, choose a curve along which to foliate, and run with enough different initial-value surfaces (each of which must satisfy the constraints initially), that eventually an intuition develops. A Will-like parameterized post-Newtonian formalism approach would also be a good idea (<https://en.wikipedia.org/wiki/Parameterized_post-Newtonian_f...>).

Unfortunately I'm unable to guess your choice of "c(m) formula".

I thought that's what the high dimension counts of string theories were: taking constants and turning them into dimensions.

Or is that too simplified?

Gravity, obvs.

> When you cross a black hole's event horizon, the radial coordinate becomes timelike, so you lose one degree of spatial freedom.

The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).

Moreover, the singularity is not a place you can poke with a stick, once you've entered the black hole. It lies in your future, in the same way as your death.

> The second half is incorrect. Since the time coordinate becomes spacelike in turn you'll still have 3 spatial degrees of freedom. Dimensions can't just vanish if you believe that spacetime is a 4D Lorentzian manifold (as physicists do).

Can we say that one of the spatial dimensions (the radial dimension) and the time dimension combine into a single dimension? After crossing the event horizon aren't they 1:1 correlated?

No, there's no change in dimensionality.

The swapping of timelike and radial dimensions are a "game" frequently played with families of coordinates, including Schwarzschild coordinates. One can apply any system of coordinates on a physical system without changing the behaviour of the physical system: coordinates are unphysical. Think of navigating around in a neighbourhood: you can talk about going forward a few blocks then turning left, after which you go forward two more blocks; or for the same journey, going "city north" a few blocks then going "city west" two blocks. Here assuming that (initially) "forward" is in the "city north" direction (and "city north" is not necessarily exactly magnetic north nor a section of a meridian of longitude). After the left turn, "forward" is "city west". There's an analogue to the discussion's (ab)use of Schwarzschild coordinates.

In Schwarzschild spacetime, without applying any system of coordinates, just floating in free-fall far from a black hole extremizes your travel in the timelike dimension. (You can do this at home: you stay put at some point on Earth (whether you use GPS latitude/longitude/altitude or some other system of coordinates) but your wristwatch keeps ticking). Inside the black hole horizon, just floating in free-fall extremizes your travel in the direction of the singularity. Far from the black hole, accelerating as strongly as you can in any direction takes travel from the timelike dimension and puts it into one or more spatial dimensions. In particular, you have the freedom to increase the spacetime interval between you and the singularity. Within the horizon, however strongly you accelerate the spacetime interval between you and the singularity shrinks. This behaviour seems to invite the use a different set of coordinates applied to a patch of space around an observer far from the black hole and a patch of space around an observer inside the horizon. It's some human cognition thing, and in the early 20th century it took decades to discover systems of coordinates that work for observers far from the black hole, at the horizon, and inside the horizon. And even today, most people don't seem to try to enhance physical intuitions by swapping among arbitrary systems of coordinates (including no coordinates) on a single physical system like a black hole and a pair of observers (one inside the horizon and one far outside the black hole).

The Schwarzschild black hole interior is still locally Lorentz-invariant everywhere (because the whole Schwarzschild spacetime is a Lorentzian manifold).

The various local interactions of the Standard Model will keep working inside a black hole. In a really tiny patch around every point, everything behaves as if its in Minkowski space (flat 4-d (3 spatial + 1 time) spacetime).

(That's one of the problems of quantum field theory on curved spacetime: the "focusing-pressure" [for experts: this is encoded in the Weyl curvature tensor; my "scare quotes" take a view of this in a Raychaudhuri equation way] gets so high that the unknown ultraviolet behaviour of the Standard Model (a quantum field theory) becomes relevant. The Weyl behaviour in Schwarzschild is that quasispherical objects are strongly prolated with the long axis aligned radially: a soccer ball or basketball starts looking like an American or Canadian or Rugby football ball. The radial stretching "spaghettifies" by ripping apart weaker bonds (like intermolecular ones, and molecular ones, and ionizing atoms), but the tangential squashing ("focusing") must eventually generate more nuclear interactions, probably up to quantum chromodynamics (QCD) energies possibly before the radial stretching starts generating hadronization.

How this works in the Standard Model is just unknown. However simpler "test" quantum field theories (fewer, or even no, interactions; and often no colour-confinement-like processes) raise really difficult questions.

Finally, back to the Standard Model as local theory: how does any allegedly quantum nonlocality behaviour work? Local here in the sence that states can be distinguished by local measurements alone. Related questions: can you entangle particles deep inside a black hole? If an entangled pair fall in together, how does the entanglement evolve? Or obsessing black hole information people, what if you throw in only one half of an entangled pair and locally measure the outside half? Nobody has great answers for these sorts of questions at present, and there's no near-term hope of testing any proposals in laboratories or via astrophysical observation.

I don't think the spacetime swap idea is particularly well explained though? Like although it's sort of mathematically true, my impression was that it's not like time suddenly becomes a dimension you're moving in once inside the event horizon, just that spacetime is acting so weird because there's now a deliberate direction where one did not exist before.

> I don't think the spacetime swap idea is particularly well explained though?

What exactly do you mean by "spacetime swap idea"? If you're saying the behavior of Schwarzschild coordinates at the event horizon is not well-understood, then I disagree. There is nothing particularly weird or surprising going on, there's just a trapped surface[0].

[0]: https://en.m.wikipedia.org/wiki/Trapped_surface

The problem is probably connecting an image of a tilted causal cone at p near but outside a regularized r_s in Schwarzschild spacetime with the idea that from p there is a limited number of null geodesics escaping to the asymptotically flat region, that the fraction decreases with decreasing regularized r coordinate, and that from p' at the trapping surface there are no such null geodesics, as all non-spacelike curves (accelerated or not) at any point on or interior to the trapping surface terminate at the singularity. The idea that the singularity inevitably lies in the future of any observer at p' is behind the "spacetime swap" notion.

Some of the problem is that Schwarzschild coordinates have surprises buried in them, and what \Delta r and \Delta t mean are not what most people tend to think.

Someone should do an ELI12 of Unruh's (ca. 2014) excellent (give or take varying the spelling of Martin Kruskal's surname) Schwarzschild BH global coordinates pedagogic review <http://theory.physics.ubc.ca/530-21/bh-coords2.pdf> and add in a bit on Fermi normal coordinates as a maybe-obvious not-a-chart follow-on to the commenary just above eqn (55). But on "maybe-obvious", Unruh has the choice line: "Since in a large number of cases, the single horizon coordinates were discovered long before Schild’s coordinates, this is an exercise in alternate reality – what could have so easily happened if only the generators of those coordinate systems had recognized what they had."

Hi. Sorry to bother you here. Could you point out what error am I making in my, I believe, very simple objection?

https://news.ycombinator.com/threads?id=scotty79&next=441240...

tl;dr The farrrr-from-the-horizon part of Schwarzschild spacetime is just not like our spacetime. Only near and outside the horizon (or better, in the absence of a horizon) does Schwarzschild become a decent physical approximation for anything in our universe.

Schwarzschild infinity is unphysical, while your notion of t(Earth) is physical because we can associate a worldline with the planet's centre of mass (COM), hold the COM at the spatial origin of a system of spacetime coordinates, and use whatever "timestamps" we like on the time axis. But we could decide that t(Earth)=infinity could be yesterday, or tomorrow, or a billion years ago, or a couple billion years from now; if we count of seconds before or after t(Earth)=infinity, we still have t'(Earth)=infinity, so it's not a very good choice of coordinate.

I think you have a misunderstanding that is probably beyond my ability to help you with, since we can't do interactive blackboard work in HN comments. The root of your problem seems to be mis-identifying the local time at Earth with the Schwarzschild time at infinity in the Schwarzschild solution. We aren't at infinity to any known black hole: between us and the most distant black holes we know of is expanding spacetime not found in Schwarzschild's solution; betwee us and the nearest black holes is substantially and lumpily curved spacetime and plenty of matter unlike Schwarzschild's unique pointlike mass surrounded by non-lumpy matterless vacuum; none of the astrophysical black holes are infinitely old today (whereas Schwarzchild black holes are infinitely old at every time, otherwise the spacetime would not be static); and in general exact solutions of the Einstein Field Equations -- even ones that are not eternal -- do not superpose cleanly with solutions for other black holes (and crucially there are no black hole mergers in Schwarzschild), ordinary stars, galaxies, clusters, and expanding spacetime. As an example: hover just above the apparent horizon of Sagittarius A*. Look at a stellar black hole in our galaxy. What do you make of infallers plunging towards the smaller black hole? What do you make of the evolution of mass of the stellar black hole, from your vantage point hugging an SMBH's horizon?

Short of taking a series of courses or finding an informal short-term tutor to walk you through particular things (you can find either at your local tertiary education school, like a community college or university), there are plenty of good textbooks on General Relativity. You seem to have found Wald's, which is probably the most rigorously and densely mathematical of several popular teaching choices, and it does not seem to have helped you. I'd guess you'd be better off with e.g. Carroll's Spacetime and Geometry or Wheeler's Gravity and Spacetime.

There is also the Israel-Darmois thin shell method, which is technically annoying but lets us cut the central part of an e.g. Schwarzschild solution and paste it into a cosmology populated with other such pasted-in subregions. We can then trace light rays from e.g. a quasar, across early expanding space to a SMBH or elliptical galaxy acting as a gravitational lens, and then across later expanding space to an approximation of our neighbourhood, adapting the rays at each shell boundary. Although there is very definitely a subregion of black hole solution in that kind of approach, the asymptotically flat part of Schwarzschild is cut away along with its distant infinities. One can compare this cutting and pasting to the Hill sphere of influence of Jupiter and those of its satellites, for example, if one were interested in a navigational plan like Juno's or JUICE's.

> Only near and outside the horizon (or better, in the absence of a horizon) does Schwarzschild become a decent physical approximation for anything in our universe.

I guess that's my point. Noting at or inside event horizon (of any kind, not just Schwarzschild solution) is physical. It's pure math, no matter how fun, has nothing to do with reality.

> But we could decide that t(Earth)=infinity could be yesterday, or tomorrow, or a billion years ago, or a couple billion years from now;

No, we cannot. Because as you stated t(Earth), by which I meant time as it passes on Earth, is physical... Now I think I should write t_Earth instead so it looks more like subscript not function application. So t_Earth = Infinity is the moment after all of the time already passed. After every finite moment already occurred. So t_Earth = Infinity doesn't really exist ever. It's purely mathematical concept. Abstract limit of the real thing.

> I think you have a misunderstanding that is probably beyond my ability to help you with, since we can't do interactive blackboard work in HN comments.

That's probably true. Even a blackboard wouldn't help because you seem to be interested mostly in minutia and specifics while my problem lies with general reality (pun intended) of all of this and which part is real and which is just extrapolation to times that don't exist and why physicists usually don't seem to care to differentiate between one part and the other.

> We aren't at infinity to any known black hole

I'm saying exactly opposite. The black hole (its event horizon to be precise) is at infinity (infinite time) to us. Any infalling object at Kruskal diagram crosses the line clearly labeled as t=infinity which in reality can't happen because there's simply isn't infinite amount of time in the universe.

> none of the astrophysical black holes are infinitely old today

To be honest that's another claim I just don't take on faith, especially in the light of the discovery of early developed galaxies and the fact that galaxies developing this early this fast would emit so much light that it would contribute to CMB (even up to 100% of it) which throws off all of our precise math theories of how everything started. I'm more inclined to believe that every astrophysical black hole existed at the the time when CMB was emitted (and before) and had exactly same size (of the event horizon) as it has today.

> and crucially there are no black hole mergers in Schwarzschild

Do you say that because they are mathematically impossible (which I would agree with) or just because Schwarzschild modeled just one black hole so there's nothing to merge with?

> hover just above the apparent horizon of Sagittarius A*. Look at a stellar black hole in our galaxy. What do you make of infallers plunging towards the smaller black hole?

Let's assume your trajectories are parallel to skip issues of special relativity. If he's closer to his event horizon than you are he's slowed down in time for you as he is for the rest of the universe outside (just slightly less). If he's farther away he lives at a pace accelerated relative to you, in the same manner that the outside world is accelerated for you. The specific math of how both of you tend to infinite time dilationas you approach your respective event horizons should show if relative time dilation between you tends to some ratio (or 1) or infinity. I don't know which is the case.

> There is also the Israel-Darmois thin shell method, which is technically annoying but lets us cut the central part of an e.g. Schwarzschild solution and paste it into a cosmology populated with other such pasted-in subregions.

I'm not that interested in pasting them statically far away. I'd really love to see what shape two Schwarzschild blackholes (and by that I mean their event horizons because, I don't believe anything beyond them is real to us) hitting each other could look like. Maybe (|)

Thanks for recommendations for further reading.

Sorry, I don't want to get into metaphysics.

Black hole mergers are studied using post-Newtonian methods and numerical methods because there is no general analytical approach known. SXS, Simulating eXtreme Spacetimes, and the black hole perturbation toolkit both have web presences, you could start there. There is also an academic literature on matching the waveforms in both regimes. These are checked against results from multimessenger astronomy.

> I'd really love to see what shape two Schwarzschild blackholes (and by that I mean their event horizons because, I don't believe anything beyond them is real to us) hitting each other could look like

This is well into the numerical relativity regime.

ETA: I'd pick <https://www.youtube.com/watch?v=jkpfXByQHxA> (SXS collab, "Event horizon for equal mass inspiral BBH in two coordinate systems") and the zoom-in at <https://www.youtube.com/watch?v=p4MTsCDtHMM> from a quickie cruise through some visualizations. There are links in the video description. Do beware that there are several types of horizon involved here, and they will not match your intuitions from Schwarzschild (see the point made in the zoom-in video description) which I would wager are built on the presence of a static Killing field which becomes null at the horizon, but the entire Killing field doesn't exist in these BH merger spacetimes. Roughly, though, if anything is in an orange region, it stays in an orange region. That includes a lot of gravitational radiation moving inwards in the purple region. [ETA again: the related Phys. Rev. D paper <https://arxiv.org/abs/1606.00436> has some nice details about the "duck bill" topology, too, and offers further detail on the purple region.]

https://www.youtube.com/@mpi_grav has several videos particularly in their NR playlist <https://www.youtube.com/watch?v=acHmN2MlJQQ&list=PLSYkic-Csf...>. Look for distortions in the BH horizons (whether it's an apparent horizon or some comparable surface gets into metaphysics; apparent horizons are at least locally observable), particularly the so-called "duck bill". Bear in mind the these are data visualizations principally of the waveforms, and the choices in intensities and hues are probably not going to be aligned with your intuition.

SXS has several videos too https://www.youtube.com/@SXSCollaboration - last month there was a major catalogue reorganization by the SXS collab so it may be that some internal links and semi-recent videos have issues.

And see for example https://www.black-holes.org/2024/10/02/BBH-mergers-with-spec...

Generally such simulations allow one to trace lightlike geodesics as a local probe of the lightlike horizon surfaces.

> I don't know which is the case

Exactly. That honest self-admission must be made near the start of any research programme.

> Any infalling object at Kruskal diagram crosses the line clearly labeled as t=infinity

Do check out Lemaître and Gullstrand-Painlevé coordinates for the Schwarzschild black hole.

I’ve always like to explore the idea of our universe being in a static 5th dimension where the 5th dimension represents randomness/entropy. The same way to think about exploring a 2d plane in a 3 dimensional space where the 3rd dimension is constant. We just happen to be in a random big bang in this 5th dimensional space

You can't have the curl operator in 4D.

What's in a 1D black hole?

I'm guessing it'd look something like this on a 1-dimensional number line:

    --- >   | > >> . << < |   < ---

/dev/null I presume

What? Wouldn't that mean an object's speed in some direction determines how time passes once it crossed over, and conversely, it would experience its old time dimension as spatial and be able to "move through (old) time" freely after crossing the event horizon?? My head hurts.

Interesting read, but even if we assume the author is correct, and the cosmos formed as a black hole in a larger universe, the question remains, how did this larger universe formed, then? Might just be impossible to know.

Questions like what was before the big bang or what is outside of our universe seem to be quite natural. However, we still don't know if these questions are well defined and have a proper meaning. For instance, a few hundred years ago, one might have asked, what happens if I go to the edge of the (flat) earth? Or one might ask: What is north of the north pole?

Thanks, GPT 4.1. It told me the same thing twelve hours ago when I asked it what was at the top. “what’s north of the North Pole”?

It is well possible that GPT-4.1 references Sean Carroll, either directly or by regurgitation.

> One sometimes hears the claim that the Big Bang was the beginning of both time and space; that to ask about spacetime “before the Big Bang” is like asking about land “north of the North Pole.”

Source: https://www.preposterousuniverse.com/writings/dtung/

I'm a regular listener of his Mindscape podcast, and that's where I got this phrase. I can highly recommend his podcast: https://www.preposterousuniverse.com/podcast/

> What is north of the north pole?

I really like this analogy for "what is outside of our universe", thank you

Not really. It’s not what’s outside of our universe. It’s why is there something instead of nothing.

It’d be like asking why is there a North Pole? Why is there an Earth to give meaning to a North Pole? Why is there a universe for the Earth to exist? And so on until you inevitably reach why is there something instead of nothing?

Maybe the larger universe is identical to the contained universe, like a fractal. That would solve the question. ;)

Might I suggest Brouwer's theorem while we figure it out

Could you elaborate? It's been a while since I've done any real analysis/etc.

A 2D version: If you have a map of the place you're in, there must be a point on the map that's in the exact place it represents.

Would be fun if we find a function f(state, time) such that for f(singularity, 14 billion years) we get our current universe. i.e.: every singularity turns into our exact universe.

Implying there’s no such thing as randomness, at any level?

No randomness when taking everything into account. I’m not an expert but I still hold out hope that if you know more about the universe than humanity does everything will be known to be deterministic.

Also implies that all singularities of the same mass are identical. I think this should be less bold of a statement. Let’s speculate that the more mass in the singularity would correspond to higher iterations in something like the Mandelbrot set. More of a resolution enhancement.

More if a scifi prompt than anything else to be fair.

While I doubt you’re unique in this, I think this is the first time I’ve seen someone say they hope there’s no such thing as free will.

Can you explain why you hope everything is deterministic?

In my way of thinking, determinism is a prerequisite for "free will". People usually speak of free will as a the idea of making their own choices. Suppose you hypothetically take a snapshot of my exact physical/mental state at the instant of decision and replay it multiple times. If I always make the same choice, that's determinism. If the outcome of the decision is sometimes different, I can't call that a "choice" or free will. It was something random that I had no control over.

Might just be a reflection of my enjoyment of life. I’ve been very lucky on most aspects. Perhaps if things were worse I’d wish for the knowledge that it could have gone differently.

But also it would be super trippy and interesting. Knowing just the mass of the universe you’d be able to peer into any time, past or present, and see exactly what happened. But then what happens around areas where people look into the local time? This happens in the show Devs. So not at all a new idea in scifi.

Not much concern for all the people less lucky than you?

Just explaining where my ideas on determinism might come from. It’s not as though I can change the laws of physics to be one way or the other.

That would mean that beings getting to know everything about the universe at some point and realizing it's deterministic was always pre-determined

Then we gotta find the black hole in our universe that contains that universe, and nuke it before they come to take our fluids!

Might not be the best idea, unless we just so happen to be all the way at the top of the sequence[1]...

1 - https://qntm.org/responsibility

Why selfish ???

It's imperative we maintain Purity Of Essence. It will bring Peace On Earth.

It’s turtles all the way down

Black holes all the way up.

This theory is in the same space:

https://en.wikipedia.org/wiki/Cosmological_natural_selection

I don’t think it has a hypothesis for the origin, though

See also the recent HN discussion about Blowtorch Theory, which has roots in (but doesn’t necessitate) CNS

  building on ten years of earlier research for a book on cosmological natural selection

I loved this overview on our current approaches to measure the expansion: https://youtu.be/WNyY1ZYSzoU

It may just be that the physical conditions of our universe just prior to the big bang are indistinguishable from that of the interior of black holes.

In that sense black holes are areas where our universe has reverted from it's low entropy state all the way back to the initial nearly infinite entropy state.

I feel like quantum physics is gently pointing us towards the idea "everything you can imagine is real at once". As in, all possible universes and physics systems and whatnot do exist in some sense of this word, and we happen to inhabit one. Just like Earth is a totally unremarkable planet in a totally unremarkable solar system in a totally unremarkable galaxy, except we popped up here so for a long time we thought there's something deeply special about Earth.

Quantum mechanics doesn't imply at all that everything possible is actual. That is a misconception.

I do agree that it makes sense, but not because of what quantum mechanics says.

Yes, it doesn't imply, but parallel universes is one of possible interpretations.

If you are referring to the many-worlds interpretation, that’s exactly what I’m talking about. There is no implication in many-worlds that every conceivable world exists as a branch of the actual wave function.

See also https://news.ycombinator.com/item?id=44253344.

The math does imply infinite universes. There are many physicists who believe that all these worlds do exist.

See also: https://en.wikipedia.org/wiki/Many-worlds_interpretation

And a video: https://www.youtube.com/watch?v=dzKWfw68M5U&list=PLsPUh22kYm...

Infinite universes doesn’t imply every possible universe. I don’t disagree about them existing.

I fail to see how this doesn't lead to "every possible world". Maybe some edge cases are ruled out, but it seems to imply every possible world as far as what that means to the imagination.

It is constrained by whatever you take as the initial conditions. The quantum state of the universe is a specific and precise thing, as well as how it evolves over time. It can be taken as a vector in Hilbert space that evolves according to the Schrödinger equation. There is no implication that the resulting path will have it visit every point in Hilbert space, or that the slices of the wave function that represent individual “worlds” somehow cover all worlds present in the unvisited points.

This sounds like "technically no but in practice yes". Like a TV screen cannot display all visible colors, but it's close enough that we consider the job done.

I find it more useful to anchor the concept of "real" in what one has direct access to. Beyond that there are many ways to describe our shared reality and the space of possible realities, including the past and future, some of which are more real than others, and go far beyond what we can imagine. Quantum physics gives us a language to expand what we can describe and imagine.

Not only does the sun not rotate around us, the rest of the galaxy doesn't even care to think that we exist. An interesting evolution in thought nonetheless.

That's a very 3D way to think of a universe.

If we wait until we understand everything perfectly before publishing, we’d never publish anything. That question may remain, but so do many others, this paper can’t address them all.

It's just recursion in the simulator.

My theory: There's no such thing as before and after “it”. It is it.

Block Universe. The more you think about it, the more probable it seems. Why should a universe pass time like a movie, if all moments could exist simultaneously? If there is no time, and it’s just a simulation formed in our brain, there doesn’t have to be a beginning nor end.

However, a complete lack of time doesn't fit with our observations and we can measure relativistic effects where time gets distorted (e.g. fast moving particles that last much longer than you'd expect due to relativity)

GR is compatible with a block universe. If anything, the relativity of simultaneity strongly suggests that we live in a block universe!

What about "bit"? Doesn't that come before "it", Mr Wheeler? :)

Just casually adding the biggest question its possible to ask

A larger black hole

if we assume the author is correct, it would cease to be a scientific endeavor.

I'd put it a bit differently, that it remains a scientific endeavor, but leaves us in the same predicament as we're in now, which is the difficult work of forming a scientific theory that can only be tested indirectly.

But who would be as cruel to put us here without giving us those answers? Who? And where did that entity come from?

Oh that was me - I figured if I let you guys work it out for yourselves, it’d be more meaningful or whatever.

As for where I came from, I gotta admit I feel curious about that too, but mostly I’m just happy to be here. Real excited to see what you do next.

I believe you, could you please give me 1000 upvotes? If you do I promise to spread the good news everywhere.

There is no other entity. We're nothing. An algebra of nothing. Combine nothing with nothing in various ways (like S-terms) and it gives you physics, among many other things. From the inside we see a universe, from the outside you would see nothing.

As an agnostic I agree, but none the less it is a whole, absurd joke to be here without any answers and I demand someone to answer me.

We apologize for the inconvenience.

This needs to be escalated. Who is your manager?

You are Number 6.

Be seeing you

That's almost a HHGG reference.

If you agree with the above comment, doesn't that make you an atheist, not agnostic?

I used to think that I was an atheist, but I realized nothing can be proven presently in any way even if I have opinions, so I decided I have to be agnostic.

So e.g. I have hunches that there's no way there is a God that's in any way as religions might think it is, and I do have a hunch that we somehow happened from probably deterministic chain reactions, but it's a hunch, it's hard to call it a belief, or it's hard to think that I believe there is no God. It's more like a hunch or a thought. Because for all I know we could be some Alien's schoolwork project, but I don't think we are.

In any case as a human I feel like I have evolutionary drive to hold someone responsible, so again I demand whoever is behind all of that to give us those answers. But that is my evolutionary drive, not that I think there's actually someone like that. It's the conflict of evolutionary brain vs the logical thoughts brain.

These different parts in the brain can also agree to many different things, which can ultimately make me much more agreeable person, if I decide to pick one of those opinions.

But I can be very disagreeable too, because I think Big Five said it can lead to success?

>So e.g. I have hunches that there's no way there is a God that's in any way as religions might think it is, and I do have a hunch that we somehow happened from probably deterministic chain reactions, but it's a hunch, it's hard to call it a belief, or it's hard to think that I believe there is no God.

Saying that you know for certain that there is no god(s) is exactly the same as saying you know for sure that there is a god(s). Being agnostic is the realization that you can't be sure one way or the other. We are not omniscient and our reasoning abilities are not flawless. You might have your strong suspicions one way or the other about whether there is a god, but if you aren't certain (as many people are) I consider that as agnostic.

> I used to think that I was an atheist, but I realized nothing can be proven presently in any way even if I have opinions, so I decided I have to be agnostic.

As an atheist myself, I find your type of agnosticism to be overly generous to the religious theories. Do you also think that Russell's Teapot might exist or do you have a limit of unlikeliness that you draw the line at?

https://en.wikipedia.org/wiki/Russell's_teapot

Why didn't anyone tell Musk to put a teapot in space instead of a Tesla?

Atheists are people that don't bleieve there is a God. Agnostics are people who don't know they are atheists. -- Aron Ra

In practice, atheists are people who think they know there is no god. Agnostics are people who realize they don’t know much at all about anything related to the origins of things and realize they don’t want to hold unprovable dogmatic beliefs like the religious people do.

I considered myself an atheist for most of my life. As I got older and learned more, this shifted. These days I consider myself agnostic.

If atheism was defined as believing a specific kind of god (e.g. the “father god in the sky that created all things in 6 days”) does not exist, I’d still consider myself an atheist.

But my agnosticism comes from an acknowledgment of our fundamentally limited understanding of certain aspects of existence, and the implications of that specific lack of understanding.

It’s not as if I believe “well maybe the god of Abraham could be real after all but I don’t know” (it seems far more likely that if there’s a god, he/she/it/they are closer to being the stuff of existence than some standalone entity). It’s more that I withhold belief entirely and don’t make absolute claims that are philosophically untenable.

If we figure out how consciousness works or achieve breakthroughs in physics, I could imagine calling myself an atheist again. Until then, agnosticism seems like the most intellectually honest position.

You’re mixing theism/atheism with gnosticism/agnosticism. They’re two separate axes.

> In practice, atheists are people who think they know there is no god.

This is generally labeled “gnostic atheism” or “strong atheism”, and only a teeny tiny fraction of people who identify as atheists take this view.

The way the vast majority of atheists use the term is as the complement set to theism. Theists believe in god(s). Atheists lack belief in gods. We don’t claim to know for certain, we just haven’t seen evidence that leads us to believe. (As you say, certainty level regarding any particular god varies depending on which one is in question.)

https://www.atheists.org/activism/resources/about-atheism/

“Gnostic atheism” is a confusing choice of words because in the context of Christianity, "gnostic" already means something quite different:

>Gnosticism is a collection of religious ideas and systems that coalesced in the late 1st century AD among early Christian sects. These diverse groups emphasized personal spiritual knowledge above the teachings, traditions, and authority of religious institutions.

I shouldn’t have written that so it sounded like both terms were equal. “Strong atheism” became the established term. My understanding is that Huxley’s coining of the term “agnosticism” was based on Christian Gnosticism’s assertion of knowledge (and it’s in the Greek root). So due to the history it’s difficult to use lower-case gnostic in a more general sense. I guess I feel like it makes it easier to understand that agnosticism is orthogonal to theism/atheism. But I should have clarified that.

In the context of Christianity, and other works of fiction, many words mean something quite different than their non-fictional use.

> In practice, atheists are people who think they know there is no god.

Many atheists find a verdict of "not guilty" on the charge "that god exists". It's the equivalent of saying "I don't believe you." That's about it.

Saying "god does not exist" is a claim that itself has a burden of proof. Most people agree there is no need to provide proof that fairies and unicorns don't exist. If you think they do: show your evidence. The default position is to think they don't exist.

That just seems to me a terribly flawed statement. I'm agnostic. Maybe there is a god, maybe there isn't, who am I to know? It always seems like incredible hubris to me when someone claims not only to know for certain one way or the other, but project their baseless beliefs onto others.

I can't 100% prove that I'm an atheist, so I'm definitely agnostic. The brain structure is constantly evolving and it's unclear how that exactly works. What is a "belief" any way, and what does it matter for?

This is why the "but the universe couldn't spawn out of nothing!" style arguments are so annoying. They completely accept that an all powerful all knowing entity could exist for all of time and not need a creator without any supporting evidence. But the origin of the universe specifically needs to be explained in detail or science is a sham.

Maybe there was no cruelty, and we were just plain matter that fell into our encapsulating black hole. Like what happenswith our own universes black holes.

Oh I have so many questions on this topic.

I've often wondered about this. I don't have any direct physics training, but it's something that felt really plausible after I learned that the mass of a black hole is linearly proportional to its swarzschild radius.

As the size of the black hole goes up, its overall density must decrease. Combined with the other observation that our universe has uniform density at large scales, it seemed really obvious to me that there existed some threshold at which the decreasing density of a very large black hole, and the fixed density of our observed universe.. would cross.

I used to muse about this question with some other tech colleagues that liked talking about physics stuff but never really got a clear answer to this.

On a side note - I'm absolutely fascinated by the implications relating to this. I'll post a follow-up thought I'm hoping somebody else has also thought about:

I've seen discussion of dark energy mostly presented as a surrogate for real energy. That there is some underlying energy "accelerating things away from each other".

I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.

In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.

The energy loss pervades to the quantum world as well - photons that start off high frequency arrive low-frequency.

It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?

When I asked this of some people in real life, I was pointed to answers that indicated that the "energy" component in dark energy is normalized into the "tension" of space somehow. As I mentioned before I'm not really studied in physics, but that explanation felt unsatisfactory to me.

Plug estimated mass of universe to your schwarzschild formula and be amazed how close it is to observable size of the universe.

I tried once, but I'm not sure what terms to throw in there. Visible matter, estimated dark matter.. anything else?

I think my estimate came out to less dense than the required threshold but it was a while back now and cobbled together with some queries to wolfram.

This is true almost by definition, and doesn’t tell us anything interesting about black holes.

There was a thread a while ago on here where the hypothesis for why things are moving apart at faster rates is down to time moving at different speeds due to mass.

So time in the void between galaxies is moving quicker than time in the galaxies, but on the grand scale of the universe the differences as up a lot.

I quite liked this theory, think is make sense, at least from my very limited understanding of this stuff.

Aka Timescape Cosmology, https://en.m.wikipedia.org/wiki/Inhomogeneous_cosmology

Would make sense if our universe is a simulation. It takes more compute power to simulate areas of high density so time naturally flows slower there.

Yeah, but also that's how time actually works too, time runs slower for us on earth than say GPS satellites so adjustments need calculated to sync the two. Again caveat is I'm more than likely either just wrong or misunderstanding it or massively oversimplifying it.

> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return. Maybe like a black hole evaporating as observed from the inside?

But in this story the black hole increases in size as matter falls into the horizon and shrinks as it evaporates, so cosmic expansion would be associated with more energy falling into the black hole than leaving it.

I thought about this part. I'm not sure we can link apparent size from outside the event horizon to apparent size from inside.

Apparent distance is something that's affected by relative frames of reference and the frames of reference are as different as as can be in this case.

>follow-up thought I'm hoping somebody else has also thought about [...] dark energy as _negative energy_ [...] Maybe like a black hole evaporating

Another layman's thoughts: Isn't the energy theoretically lost by black holes so faint it's currently undetectable? And isn't the amount of dark energy theorized to be the major component of the observable universe? It seems like the numbers wouldn't add up?

I don't have enough of the background to speculate about the numbers. Dark energy feels "big" if we think of it in terms of the actual energy it would take to accelerate the universe away from itself at the rate that we see.. but the rate that we see is affected by our frame of reference, along with distances and everything else.

I'm gonna pull out my lay understanding again. An evaporating black hole, as it gets smaller, should get more dense and be associated with a higher local spacetime curvature, no? The effect of which would be to slow down apparent time for observers within the system. Maybe that affects observed distance and rates of speed at which things seem to be happening when we look out into the sky?

Sometimes I regret not caring enough about calculus in university.

A black hole is really just a singularity with infinite density by definition, but finite mass.

The size and density of the Schwarzschild volume is determined only by mass (stationary, non-rotating). It's proportional to the inverse square of mass. Density = 3c⁶/32πG³M².

SMBHs have densities ~0.5 kg/m³ between thin air and water.

Stellar BHs are ~1e19 kg/m³ several orders of magnitude more than a neutron star.

> Combined with the other observation that our universe has uniform density at large scales

s/has/had at the time of recombination

It is largely an assumption of LCDM that we can treat the universe as practically homogeneous throughout its entire evolution but potentially not a very well-founded at that [0, 1].

> I always felt uncomfortable with that characterization. It seems more reasonable to me to think of dark energy as _negative energy_ - i.e. a loss of overall energy.

Your intuition is correct. If the Lambda term in the Einstein field equations is moved over to the side of the energy momentum tensor, it takes on the role of a negative contribution (provided Lambda > 0, as observations seem to indicate).

> In a classical system, two things moving away from each other stores potential energy that can be recouped at some later time. Dark energy doesn't work this way - things accelerate away from each other the further apart they are. From a global perspective, it's an energy loss.

Note that there is no global energy conservation in General Relativity[2], only at a local scale[3]. Heck, you'll already struggle to define what the energy is of a given piece of spacetime in a meaningful and generic manner[4, 5]. In other words, violations of energy conservation due to spacetime expanding or contracting (a strictly non-local phenomenon), like in the case of the cosmic redshift, are expected and our intuition from classical mechanics only takes you so far.

> It somehow feels more appropriate to me to think of dark energy as energy being extracted out of the universe, in some form never to return.

Dark energy aka the cosmological constant term in the Einstein field equations is a constant term, as the name suggests. Yes, there can be energy loss due to spacetime expanding (see above) but that doesn't change the gravitational constant.

[0]: https://en.wikipedia.org/wiki/Cosmic_web

[1]: https://en.m.wikipedia.org/wiki/Inhomogeneous_cosmology

[2]: https://en.m.wikipedia.org/wiki/Conservation_of_energy

[3]: https://en.m.wikipedia.org/wiki/Stress%E2%80%93energy_tensor

[4]: https://arxiv.org/abs/1510.02931

[5]: https://en.m.wikipedia.org/wiki/Mass_in_general_relativity

Interesting reading - this is the first thorough response I've gotten to some of these question. Will check out the reading material.

> As the size of the black hole goes up, its overall density must decrease.

The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.

> and the fixed density of our observed universe

Our universe is expanding. It's density is not fixed.

You really want to be thinking about this in terms of entropy and not matter.

Yeah I was referencing the event horizon as the most meaningful measure of size.

And whether the density is fixed over time or not doesn't affect the question. Let's take the universe at its current average mass/energy density - whatever the "true" measure of that is.

To the best of our understanding, at large scales the density is uniform. So if we consider a suitably large spherical volume of space within our (presumably infinite) universe.. that volume will have an average mass/energy content greater than the threshold amount for a black hole of that apparent volume (again, using the external event horizon frame).

So that suggested to me that either we live in a finite universe, or we must be on the inside of an event horizon. It seems like an unavoidable conclusion.

It's a mathematical model, not reality. I don't believe scientists believe an actual infinitely dense object exists at the center of black holes.

> The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.

Arguing semantics is rather boring when it's obvious you understood the point he was trying to make.

> Our universe is expanding. It's density is not fixed.

None of that precludes uniform density at large scales.

>> Our universe is expanding. It's density is not fixed.

> None of that precludes uniform density at large scales.

According to observation, the universe is expanding. An argument that it's really static at a large scale would require contradicting observational evidence, but none exists. A theory that requires abandoning observational evidence bears a special burden, which this theory lacks.

Black holes are capable of expanding, they do it by eating material from outside.

The universe's expansion, and a black hole's increase in mass over time, are unrelated phenomena. We could have one without the other. In fact, because of Hawking radiation, in the far future we might see a larger universe accompanied by smaller black holes.

I think a point they are trying to make is that the border of a black hole is only to us outside observers, if you yourself fell into one you wouldn't notice anything specific when you crossed the boundary. The popular example of hawking radiation references a border and pairs of particles, however its actually only to help people understand the idea of what is going on

> if you yourself fell into one you wouldn't notice anything specific when you crossed the boundary.

Wouldn't you notice that fairly suddenly everything's getting brighter because all the light/radiation is sucked back in?

I learned recently on [a video](https://youtu.be/a4vHwY0wMjs?t=246) that for very large black holes , we suspect there is no difference.

For smaller BH, the gravity gradient is higher and it would be detectable.

>> As the size of the black hole goes up, its overall density must decrease.

> The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.

>> and the fixed density of our observed universe

> Our universe is expanding. It's density is not fixed.

These are both correct and germane points. So why was this post downvoted? Physics isn't a popularity contest, it relies on evidence.

I think given time at a blackboard we could walk through Newton's cannon in the context of Poisson gravity, and for extra credit with the cannonball inducing a perturbation of the Poisson vector field. Even without the cannonball's backreaction, the Poisson picture offers a nice image of the gravitational potential energy at the top of the cannonball's inertial (ballistic) curve. We would then consider a cosmology like our own but with a recollapse: at maximum extent there is some (quasi-)Newtonian notion of gravitational potential energy for all the galaxies, since they are at the point where they begin free-falling back into a denser configuration. It's then the usual story of relating kinetic and potential energy, and recognizing that the standard cosmological frame is close to Newtonian by design. (We also have to stop this approach when the galaxies are merging enough that radiation pressure and gas ram pressure become relevant, because the errors become astronomical).

Since we don't have a blackboard in front of us to interact with, I can suggest Alan Guth's lecture notes on Newtonian cosmology. (Guth is credited with discovering cosmic inflation.) https://web.mit.edu/8.286/www/lecn18/ln03-euf18.pdf See around eqn (3.3). You could also borrow a copy of Baumann's textbook <https://www.cambridge.org/highereducation/books/cosmology/53...> which studies the Poisson equation for various spacetimes, however a static spacetime gets most of the focus.

A universe which expands forever, or which expands faster in the later universe, makes a mess of this sort of approach to calculating a gravitational potential energy. So does any apparent recession velocity that's a large fraction of c (inducing significant redshift, whatever the recession (pseudo-)"force" might be).

However, the general idea is that there is a relationship between the kinetic energy a receding galaxy (in a system of coordinates -- a "frame" -- in which these kinematics appear) and a gravitational potential energy still occurs in a non-recollapsing universe. It's just that the potential energy climbs forever, and you get an equivalent to gravitational time dilation between galaxies at different gravitational potentials (i.e., between early-universe galaxies and higher-potential modern-times galaxies).

Accelerometers in galaxies will not show a cosmic acceleration for any galaxy; they're all really close to freely-falling (local galaxy-galaxy interactions are real -- collisions and mergers and close-calls happen -- but wash out over cosmological distances; look up "peculiar velocity" for details). Therefore we can conclude that there's no real force imposing acceleration on the galaxies. However that's also true of a cannonball in a ballistic trajectory, including one on an escape trajectory or one that enters into a stable orbit. Consequently one can draw some practical comparisons between a ballistic launch from Earth into deep space and galaxies spreading out from an initially denser early part of an expanding cosmos.

> Dark energy as energy being extracted out of the universe

No, it's just a way of thinking about whatever is driving the expansion, and that doesn't dilute away with the expansion as ordinary matter and radiation does. It's not even a "real" energy in the sense that it is only an energy in the cosmological frame, and is a frame-dependent scalar quantity, whereas in the fuller theory it's just a multiplier of the metric tensor. So it's the full relativistic metric doing the work but we absorb some of that into cosmological coordinates in the cosmological frame of reference, carving up the metric tensor into a set of vectors including an expansion vector identical at every point in spacetime.

The expansion vector can also be thought of in terms of pressure: in a collapsing cosmological frame, a pressure drives galaxies together into a denser configuration. The inverse of pressure is tension, so in an expanding cosmological frame, it's a tension that pulls galaxies apart into a sparser configuration. (The reason one uses pressure or its inverse is that the matter fields are idealized as a set of perfect fluids at rest in the cosmological frame; each such fluid has an associated density and internal pressure which evolve with the expansion or contraction of the cosmos, generally becoming less positive in the time-direction of expansion (i.e., in the future direction in a universe like ours). Another way of thinking about pressure is as a measure of isotropic inflow of energy-momentum into a point; increasing pressure at a point therefore increases the curvature at that point. Tension is an isotropic outflow, and so positive tension is repulsive as opposed to the attraction from positive pressure.)

> that explanation felt unsatisfactory to me

Hopefully the above helps a bit. Unfortunately there's only so much teaching one might do in a series of HN comments, and ultimately one probably is better served in developing some grounding in the full Einstein Field Equations / Friedmann-Lemaître equations before thinking in quasi-Newtonian ways. Going the other direction tends to lead to misunderstandings and developing false intuitions when running into situations where the quasi-Newtonian picture needs post-Newtonian correction terms.

It's cool that you have all sorts of questions. You could consider signing up for part time / non-business-hours courses in relativity at a nearby community college or the equivalent, depending on where you are, or maybe just bringing a hot lunch to a lecturer there in exchange for a quick informal tutorial. Anything like that is bound to get you to better answers than raising comments on HN threads about astrophysics in the broadest sense, as answers here are often somewhere between non-standard and unreliable.

That is a very interesting idea… the equation and its assumptions doesn’t seem to have any exceptions so it does strongly suggest our universe is a black hole, inside a black hole?

> The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence.

It is indeed "often described" in the media as such. However, that is _not_ the currently accepted theory. "What if there were no space and time before the Big Bang" is just Stephen Hawking's pet theory.

A more accurate summation would be that our theories do not permit us to go back beyond what appears to be the "Big Bang", and indeed, we can't quite get to it either, since the need for Quantum Gravity becomes too great as we get to what seems to be the "zero time". We have no principled, reasonable way to make any claims about what came before the point where our theories break down, and that includes the claim that there was no space or time at all before then.

Thus, anything and everything you've heard about what is there "before the big bang" has always been speculation. I mention this because sometimes people read the science media, which is always reporting on this speculation, and think that the reporting on the speculation constitutes "science" constantly changing its mind, but that's not the case here. Science has consistently not had a justifiable position on this topic, ever. It has always been speculation. It is the press that often fails to make this clear and writes stories in terms of what "science" has "discovered", but any claims of certainty in this area are not the claims of "science".

Interesting thing with this work is that it does create an observable, testable hypothesis: slightly positive curvature of the universe.

Seems inevitable that we'll discover we aren't the only universe / only cycle.

We went from thinking the Earth was the center of the universe, to the sun being the center of the universe, and the next obvious step is our universe isn't at the center of universes.

What people seem to not be able to conceptualize, consciously or not, is that there really is no "before" the Big Bang in the standard model (Lambda-CDM), if time itself exists only after t=0.

The Lambda CDM does not really say that. As other commenters have pointed out, Lambda-CDM is silent on the very earliest few moments of the universe where quantum gravity would be required.

What is the currently accepted theory?

We have no theories working at those conditions. Wiki says

> General relativity also predicts that the initial state of the universe, at the beginning of the Big Bang, was a singularity of infinite density and temperature.[6][obsolete source] However, classical gravitational theories are not expected to be accurate under these conditions, and a quantum description is likely needed[7].

https://en.wikipedia.org/wiki/Gravitational_singularity

> [6][obsolete source]

I didn't know but apparently wikipedia treats old sources as obsolete, doesn't matter if there's new information or not that would make it obsolete.

I wonder if any sources supporting the notion that the earth is round must be updated every couple of years with a new source or study.

That exemplifies a much deeper problem than good information, “Good Law”: https://en.m.wikipedia.org/wiki/Good_law

As an aside, the earth is almost flat, just not nearly as flat as the Universe.

> As an aside, the earth is almost flat, just not nearly as flat as the Universe.

Source? And make sure to update your response every few years.

It’s in the Library of Babylon. My standing citation.

Obsolete doesn't just mean old, it means superseded by newer information.

I agree with you, wikipedia seems to disagree with both of us

This is the best theory we have:

https://en.wikipedia.org/wiki/The_Last_Question

At t=0 or "before" none

Might as well believe in God if you’re going to believe in spontaneous accidental creation…

Why not? If you can't observe it, test it, and reproduce it, then it lies outside the realm of science and in the realm of belief. Until someone figures out a way to experimentally verify the big bang hypothesis (or any other explanation for the origin of the universe or what came "before"), it's entirely fair to attribute it to whatever you feel like, be it a god or anything else. There is no law of the universe that guarantees that science is capable of answering all questions.

Well, I think surely the entirely fair thing to do is to just admit we don't know rather than make any attribution or imply any possession of an answer to those questions?

Humans have created models for things they don't understand throughout human history. Certainly throughout any recorded history. We don't know, but we have a model that fits pretty well and we can guess at the underlying causes. We'll be wrong more often than right, but over time as we get more data and we can test more things, we get a more accurate model. Not necessarily the right model. We may never get that. But based on those models, "guesses" are far more reliable than "The Sun is a god who circles the world".

While we don't "know" how gravity works we can explain it and model it much more accurately now than when logos was the explanation. Providing those details is far more useful than a simple "we don't know."

Certainly, that's also perfectly fair. The thing to keep in mind is that some people derive utility from belief in some sort of creator, so ultimately it's an argument of values (specifically, you're looking to argue that people should prefer uncertainty to unprovable (but also undisprovable!) certainty).

If you can't observe it, test it, and reproduce it, then it lies outside of the realm of (natural) science and may lie within the realm of mathematics, philosophy, or (gasp) theology.

> There is no law of the universe that guarantees that science is capable of answering all questions.

There's a name for a more nuanced version of this "law" and there's a good amount of work being done arguing for and against weaker and stronger versions of it: https://plato.stanford.edu/entries/sufficient-reason/

I think it's important to clarify that the question of whether or not everything has a cause is itself outside of science. Science is about determining what a cause is likely to be, using the universe itself as a source of truth, and constrained by fundamental limits on our ability to observe and experiment. Which is to say, even if the philosophers conclude that everything must have a cause, there is still no law that says that we (as scientific agents of a universe that is attempting to understand itself) are capable of determining every possible cause.

There's quite a big philosophical difference between "there exists a point beyond which it is possible to make observations" and "the universe was created by an omnipotent being"

Verily, for all knowest that the gods live up in the sky, which is forever unreachable and unobservable by any man.

Yes. The man can never see consciousness. Only consciousness can see man.

Am omnipotent being is a necessity for making observations. A lot of religions considers consciousness as God.

I don't see how this is. It seems eminently reasonable that observation can simply be performed by sub-omnipotent beings.

Life is one omnipotent being. It's just ego, thoughts and social identity that creates the illusion of multiple beings.

But ego and names are made up. Separation just thoughts. The more life believes in thoughts it becomes divided.

But the waves and ocean are one.

An illusion is something that disappears when you see behind it, no? How goes it for the illusion of the both of us being connected but separate beings? I think at the very least it would require consent of both parties to merge, so as long as I don’t believe it, you have to live as a being separate from me, and as such it stays „an illusion“ for you that we are one; merely an idea, a potential option maybe, no?

You can declare Life to mean the complex interplay of every living organism, but I don’t see how you can go as far as to claim our physical and mental separateness is not there at all? After all, we need boundaries between „us“ to not be utterly alone. I like to think even of „my“ body more as a federated system, like Life maybe but on a smaller scale. I have some influence on it but not full control. In fact, one could say the polarities in the physical realm are Nature (towards separation, entropy; Kaos) and Life (actively working towards one, requires energy to keep matter ordered; Order).

(Alone, all-one)

If we merge, by definition the „I“ and „you“ have to die; both of us stop existing. The merger creates something new, a „we“. A single entity. We can then use the definition of identity to call this new we „I“. Rinse and repeat until back to being alone/all-one?

Do you really want to be all-one? Omnipotent, full of all potentials/possibilities? I don’t know. I am already overwhelmed with my limited human potential/possibilities/options. And I prefer to not be alone. I prefer to stay separate, and keep my identity.

I don't get it. Put all life together and its all pretty obviously NOT omnipotent as far as I can tell. Every living thing on earth could spontaneously have an desire about the state affairs on Pluto and I don't see any reason to believe anything on Pluto would change.

Can you find any separation in your experience without using beliefs.

To quote the philosopher Hank Hill, "Yeah, yeah, I know, everything is one way, then it's the opposite."

Anything outside of what we can observe will always be based on faith anyway. We'll probably never understand what's "before" the big bang, wether it make sense to ask that question or why something exists rather than nothing.

I don't think so - god is substantially less parsimonious. But in the end, I think you're sort of using two different notions of belief as if they were the same.

I believe (lowercase b) in all sorts of stuff, scientific and otherwise, but believing in God typically indicates some kind of act of faith, which is to say, ultimately, to believe in something despite the absence of evidence for it and for some deeper reason than can be furnished by a warrant of some kind. I can believe in the spontaneous generation of the universe in the lowercase b sense of the word without really having anything to do at all with the latter kind of belief, which I think is kind of dumb.

Historically, in the West at least, the ability or inability to reason one's way to the existence of God determined whether you needed to rely on faith or not.

https://www.vatican.va/content/pius-xii/en/encyclicals/docum...

Nice, paragraph 5 and he's already into "evolution is fiction and commies love it."

You didn't read closely enough. He is condemning the notion that evolution explains the origin of all things (as ridiculous as that sounds...it was a kind of ontological darwinism; no reasonable person holds this opinion today).

Sort of like believing that we have free will.

To me, calling the unknown "God" is imposing a term loaded with human preconception and biases in exactly the place you don't want those things.

You're confusing belief with accepting the current scientific consensus.

The Big Bang theory was created by a Catholic priest. So yes.

And the Big Bang was created by the priest's God.

Which God? Vishnu? Ra? Amatarasu?

Prince Philip? https://en.wikipedia.org/wiki/Prince_Philip_movement

Assume God exists.

Various isolated cultures are going to come up with different names for God.

This like saying which Sun? Surya, Ra or Helios?

All are different names of sun. But there is only one sun.

On the other hand, there are a lot of stars and different cultures might give them different names and yet there really are many of them.

Furthermore, assume God doesn't exist. Lots of cultures might invent god for various reasons and they'd naturally have different names and attributes for them, which in fact seems to be the current state of affairs.

In fact, if we assume God exists and is actively in communication with humans, its actually a bit weird that different human cultures would have different conceptions and names for that being. Why didn't it just give everyone the same name and information?

Why do you think God will have a name? Name is used by humans to identity a person among a lot of other persons. Why will God have a name if it is the only thing in existence?

To answer the question of why humans give name to God. It's to make god more relatable so that they can workshop it. And use devotion to come closer with it. Look up Bhakti Yoga.

How about just having one God vs many? If there is a single omnipotent being, why do various cultures have multiple gods? And why do different cultures’ gods tell them different things?

Fair question. So my understanding is God is consciousness. It's omnipotent, all knowing and eternal. It's the only thing which is constant in your life and it sees everything you do.

Now, you cannot worship consciousness as humans because it's invisible and you can never imagine it. You need a version of consciousness that you can see as well as you can relate to. So cultures invent localized version of God which people can relate to. And of course it will have attributes similar to that of the culture. But the properties kind of still hold. Like all knowing, powerful etc.

This reminds me of what Jordan Peterson does, which is to define "God" as something that we know exists. He defines it as the fundamental value upon which other values are built; you define it as consciousness.

I've always thought arguments like these are unnecessarily applying a term loaded with human conceptions and biases in a way that doesn't shed any further light on the thing it's applied to. Like, what do we gain by defining "God" as consciousness? Why can't we just say "consciousness"? And is it worth the added confusion that when we say "God", we now don't mean what most people think "God" is?

The only reason I can come up with to do this is discomfort at saying, "I don't believe in God."

I’m sorry but that’s a lot of words to provide no additional clarity. God is consciousness. So if there are no conscious beings in the universe there is no god? Or is this just renaming something that already has a meaning into god?

I didn't say he'd have a name, I said he'd give humans a uniform one since, according to, for instance, the Christian worldview he is purported to be interested in human affairs.

But that sun has never been a pharoah of Egypt.

If the only common factor is a belief that 'something' created 'something', you're really not saying anything worth evaluating.

> Various isolated cultures are going to come up with different names for God.

People hate not knowing the answer to the big questions so much that they'll readily accept whatever answers are served up to them.

> This like saying which Sun? Surya, Ra or Helios?

The difference is that the sun is readily observed. A conveniently invisible god isn't.

> All are different names of sun. But there is only one sun.

And there's only one human nature, which is why it's not surprising that common artefacts of human nature (e.g. religion) emerged universally throughout ancient human cultures.

Try to find who you are and you will find god.

The gods in different cultures aren't just named differently, have different properties.

[flagged]

How so? If you attribute it to an earlier universe, you are just pushing the problem further back. It doesn't seem to be a proof or even a mild indication.

The universe casually didn't follow the laws of physics immediately after the Big Bang, an improbable event directly after an improbable event. No explanation has been found, even according to CERN, why everything that was created was not spontaneously annihilated. Attributing that to a divine intervention is the most probable explanation. CERN attributing this to "Some unknown entity" is humorous.

One theory (which CERN is using) is to argue that almost all matter was destroyed, and that the current observable universe is merely the tiny leftover due to slight differences in behavior, making the Big Bang look more like the Ludicrous Bang. This, of course, just contributes to religious snickering at how all problems are solved by adding another billion years to the timeline, over and over.

https://home.cern/science/physics/matter-antimatter-asymmetr...

Edit to reply: They behave differently; but why there is more of one than the other, remains unexplained; as regardless of how they behave, both should have been initially created in equal numbers. As for Sabine Hossenfelder's quote, that's a religious-faith level cop-out. When science requires faith, should it not be treated as a religion?

> No explanation has been found, even according to CERN

Incorrect.

First, let's be clear, "our understanding of the laws of physics" is not "the actual laws of physics". Every physicist knows this. The universe always follows the real laws, physicists are very excited about the difference because it's a chance to win a Nobel Prize.

For example, the one in 1980 for the discovery (in 1964, they're slow to award the prize) of CP violation in decays of neutral kaons, which is fancy physics language for "matter and antimatter do not behave the same way". This year, the LHCb experiment in CERN also discovered CP violation in baryons.

In fact, this is in your own linked article from CERN: """In the past few decades, particle-physics experiments have shown that the laws of nature do not apply equally to matter and antimatter. Physicists are keen to discover the reasons why."""

That said, personally I like the response from Sabine Hossenfelder: There's nothing to be explained, conservation laws only apply to time-evolution of a system, not to the initial conditions.

We don't look for a reason why the mass-energy was non-zero, why do we even need one for why the baryon number isn't zero?

> Attributing that to a divine intervention is the most probable explanation.

You lost me here. It seems humans have a predisposition to believe in divine beings, so this just sounds like taking human biases as a basis for truth. What's wrong with saying, "I don't know?"

why do the religious like snickering at people so much?

Things existing is pretty miraculous! How is any of this stuff here?!?!?

Belief in anything is completely trivial unless you act based on those beliefs. No one is going to waste time worshiping, or murder someone over, the "nothing" from before "something".

> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.

Does it also follow that black holes in our universe contain universes internally, beyond their event horizons?! Seems like it should. Mind-blowing.

It's not a new idea, although I don't think it would be accurate to describe the other universes as "contained" within the black hole.

https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassi...

Black hole to White hole to Black hole

It’s holes all the way down

That's a wholly a whole lot of holes.

Does it also follow that black holes in our universe contain universes internally, beyond their event horizons?!

Not necessarily. It's not clear that any are massive enough to cross the threshold required for the "bounce."

Damn, I would not have guessed that Men In Black was actually a documentary...

I thought the universe they were saving in that was in some kind of "fish bowl" type universe (galaxy?)

Suggested hard sci-fi light reading: "Cosm" by Gregory Benford, 1999. A universe the size of a bowling ball created in a laboratory. The scientist responsible for it, keeping it safe and on the run from gvt spooks. They want to protect it for as long as it lasts, and since its time is as relative as its size, they won't have long to wait.

Added.

Opinions:

A) I love all the scifi book recommendations that cone up on HN

B) i wish you’d all stop recommending great and amazing books. My queue is so backlogged and jammed I'm never going to catch up.

Same here. My interest in the Sci-Fi genre started with an HN comment recommending Blindsight, by Peter Watts.

Several comments and sci-fi series later, and I’m currently reading about spacefaring sentient spiders.

OK then, I'd be remiss if I didn't mention my own sci-fi book I put out there free forever to listen ( https://www.youtube.com/watch?v=mtxgpaXp9vA ) and free forever to read/download/listen ( https://archive.org/details/stargazer-steven-pitzl ) because I don't want to navigate the self-publishing world, just want some feedback before I die.

Only joking, I'm remiss anyways.

So many books, so little time...

There needs to be some kind of hackernews library or goodread. I have enjoyed many books (and some no so much) but always on the look out for books.

You'd like this then: https://hackernewsbooks.com

That would be fantastic.

If only we had an even bigger universe, we would have more time... is that how it works?

Like this? https://hacker-recommended-books.vercel.app/category/5/past-...

That’s a very cool app, but I think it is missing many, many references to books in HN comments? It only has like 15 total sci-fi books. I don’t see any of my comments mentioning some sci-fi books.

It's a bit old. I bookmarked it a while ago, I don't think it has an update mechanism. A daily frontpage pull + AI parsing should be enough to keep it up to date.

What's a couple dozen books (and video games) in my backlog when I have a thousand websites there?

Please share the queue!

Rick and Morty episode (season 2 episode 6, 'The Ricks Must be Crazy') where it turns out rick has created a whole universe inside his spaceship battery who's whole purpose is to produce energy to run his spaceship. A scientist within this microverse creates a miniverse ....

Should not be microverse inside miniverse?

This sounds similar to Horton Hears a Who.

They exist in the same cinematic universe.

Microcosmic God - Theodore Sturgeon (1941)

I seem to remember a similar Star Trek episode; DS9, IIRC.

"playing god", s2e17

I remember that, and the enormous plot hole that they could move the thing in a transporter!

I'm not a scientist or astrophysicist but i do believe in science, is it ok to believe that we as humans and all our scientific development still very very far from proving anything remotely close to how the universe got created? I feel this subject is for humanity in year 2600 to start discussing it.

Scientist still can show their theories and search papers and i can't understand a shit but i don't believe in any theory that proves how the universe got created.

Science is a process, not a source of truth. It has a very practical lens, which is very utilitarian, does the knowledge and models allow for invention or prediction that works in our reality for some current need.

The assumption is, you never really know, but if the model in which the theory says X, is able to predict something in the future or some experiment for Y, than that model appears to better approximate reality. Or is that knowledge and model allowing us to now do something we could not before, etc.

Over time, it course corrects to improve its knowledge and models in ways that show better results for prediction or invention.

"Proving anything" is kind of fuzzy. We've got very solid evidence that some sort of big bang happened. We can see the galaxies flying away from a common point, and since we can count backwards, we can know roughly when they probably would've been in the same spot. The how and why, and the what happened before, those are very unknown, although we've got a surprising amount of knowledge of what the first few seconds were probably like.

It's not about belief, it's about observing, collecting data & evidence, and proposing possible explanations. As new observations and evidence are found the possible explanations are refined. No one credible is claiming hard proof of anything at this point.

Agreed, people often mix that up, but you have to adopt a probabilistic mindset, you can believe the coin with land on its head, but you also know that based on the weight and curvature of the coin it will land on its tail 68% of the time you flip it, etc. Then choosing tail is no longer a belief, it is simply going with the choice that is backed by prior observation, experiments, models, etc.

You might still lose, and so you might choose to also believe it will land on tail this time, but the rationale for choosing tail was not based on a belief system, but the going information and where it points too.

Before we can prove, we must first wonder. We proceed by small steps, and if we don't start discussing it now, 2600 will still be too early.

Belief is acting as if something, for which no evidence has been given, is true. Imagination, taken too far. No one is telling you to believe anything here, they're suggesting we search for clues to support or disprove a theory. Or don't, it's up to you.

That's not the definition of belief. Belief can have various levels of different kinds of evidence behind it. Scientific, historical, philosophical, experiential, etc. A belief could have more or less scientific evidence than other beliefs, but rarely is belief predicated on no evidence whatsoever.

Do I really have to include the exact definition of every word I ever use? You know damn well I'm talking about blind faith and scientific evidence. And you know damn well OP is completely dismissing a theory because they're confusing it with a demand for blind faith. I don't care what people want to believe, but if they start labeling things incorrectly, I'm going to point it out.

I think the phrase 'believe in science' is weird; it's nearly as problematic as "I have faith in science".

It can be, but generally the concept of 'belief' isn't attributed to ground truths; it's just 'the truth', you rarely hear the phrase "I believe 2 and 2 is 4." , it's just '2 and 2 is 4.' -- I think that's important.

In fact, a lot of people insert the word 'believe' to insert a concept of self-doubt. "What was our last test results passing rate?" "I believe it was around 95 percent.."

But semantics aside here's the real question : Why do you have some kind of notion that you should 'believe' anything without being able to understand it? Just trust in the world and those around you?

We haven't figured origin yet, so let's get off that, but when a scientist of some sort makes a discovery, they release evidence and methods , and you decide to believe the conclusions without an understanding of the work -- well that's just a display of faith. Faith in the scientist themselves, the system they work within, and the society you're in.

Which leads me to say this : If you make an effort to begin to understand the frameworks and systems which lead to scientific conclusions you can largely remove the faith and belief elements up until you hit the very highest spectrums of each field where speculation comes back into play.

tl;dr : if you 'cant understand a shit', you don't put any leg-work in and make an effort to speak the language, you'll probably end back up in beliefs rather than an ever increasing codex of knowledge -- regardless of the field. That's okay -- but it doesn't offer the same benefits as knowledge -- it just lets one say things like "I don't believe in any theory..."

I have immense respect for astrophysicists, but the data we're dealing with is extremely far away and relies on a lot of interlocking assumptions.

I stumbled upon this paper [1, 2] last night that challenges the CMB, and thus the underpinning of much of our understanding about the age and evolution of the universe. As a layperson, I don't know the impact factor of the "Nuclear Physics B" journal - if this is just junk or if this is a claim that will pan out.

My point is that it feels like we're building on a lot of observations that are all super indirect. I know I'm just a layperson, but that feels weird when reading assertions about these things.

Our understanding of the universe is relatively new. We don't have a lot of energy or resolution in our observations. The fact that we can sniff the molecular spectra of exoplanets is so amazing and that part feels totally concrete and rock-solid. But I get skeptical when I see claims that we know how the universe began or how it will end. Is our evidence that good? Are our models? Are we basing everything on assumptions?

[1] https://arxiv.org/abs/2505.04687

[2] https://www.youtube.com/watch?v=Xb69yPNgX-Q

> But I get skeptical when I see claims that we know how the universe began or how it will end

Absolutely, but you are interpreting it in the rewritten headline money making attention grabbing version.

The original version of the claims always say that from some observation, experiments, and projection from known models it derives that the universe likely began this way, or will end that way, etc.

That means, of all the going hypothesis, this might be the one with the best chances of being true, or close to the truth. It's not an absolute, but its the one that has the most chances due to the evidence behind it.

You don't believe in science, you believe in a metaphysical claim about science that you haven't articulated.

But that's why science is so cool, it doesn't matter what we believe, it only matters if your theory fits the facts and makes good predictions. If it doesn't, you can chuck it in the bin without guilt. Unlike beliefs, which often can cause psychic trauma if reality doesn't match the belief of the individual.

If we can't even predict inflation rates maybe we should hold off on explaining the birth of the entire universe, yeah?

Predicting inflation rates may be harder than discovering the birth of the universe actually, because it would require perfect knowledge of the present and by the time you compute it it's out of date.

We can claim to simulate the first femtoseconds of the universe...model nuclear detonations in software down to quantum effects....but 340 million citizens buying gas and groceries? That’s somehow beyond our grasp... :-)

Maybe the problem isn’t complexity, but that science gets arrogant when it drifts into realms where its claims can’t be falsified ;-)

The beginning of the universe is a start state we have theories about, that we can apply our system of physic to calculate once. A computer that calculates an economy might violate the halting problem because it would need to know when it itself is finished to calculate its own electricity costs, as well as every other algorithm in an economy.

>Maybe the problem isn’t complexity

It most certainly is. Each of those 340 million citizens is a unique person, with unique circumstances. You can't fit an equation to that.

>science gets arrogant where its claims can't be falsified

This article proposes testable predictions?

You’re fundamentally misunderstanding the difference between biology and physics.

The difference is clear: https://xkcd.com/435/

If the universe does have a positive curvature as this predicts, would that mean that if we look out into space, we could see the same galaxies multiple times? Or even our own galaxy in the past? Or is the predicted curvature slight enough that anything we might see multiple times is already beyond the limits of visibility due to universe expansion?

Only if the circumference of the universe is small enough for light to have made the round trip since the universe began. But we think that the universe is much larger than that.

https://en.wikipedia.org/wiki/Particle_horizon

A few years ago a popular idea was that our universe existed as an hologram on the surface of a black hole.

Recently I saw also a theory that black hole might not, in fact, exist as we thought, and may be instead something called 'gravastars', where large stars do not collapse in an infinite point but instead the mass reaches a maximum density and hardness and become sorts of empty bubbles.

Now this. It's not exactly a new idea, I remember reading about black hole cosmology 10 years ago.

Sooo... My uneducated, pop-sci fueled imagination now sees the universe as a mathematical function of a fractal looking like a shell with patterns on it, and those patterns interact or 'fold' in a way where the patterns themselves can be thought of as shells with patterns on them, and each shell creates something that, from the inside, looks like a new dimension of space or time, and what we think of as black holes are the next fold. Does that make sense?

It makes sense to me... I think. And I like this vision as well. It would explain the big bang (initial black hole formation), why the universe is expending (at probably non constant rates over time) which would be the black hole "ingesting" matter and growing and maybe also why time and space are one. Same as you, a take from complete uneducated pop-sci fueled imagination.

The bounce to me has always seemed more intuitive than the bang, but man, when it comes to the quantum universe I've learned to just check intuition at the door.

The word "research" in this title is a handy placeholder for indeterminate conjecture. No research happened, it's a theory he made up.

I would argue that theory is a critical part of the research process and is therefore research.

There’s of course a line between simply coming up with ideas that are quickly provably wrong or inconsistent vs generating ideas that are consistent and not quickly falsified. It’s especially valuable the ideas are falsifiable and it seems like this is the case here.

As such, theory finds patterns in existing knowns, makes some leaps and tries to connect them. Then empirical evidence can help solidify or falsify those ideas. But we tend not to just connect dots of empirical data without attempting to know the casual relationship, otherwise the connections can be rather nonsensical or may have weak predictive power.

With all that said I didn’t read the paper in detail nor am I qualified in this domain to say if it’s quackery or a reasonable shot a developing some new theory. It is peer reviewed and published in APS so I suspect it’s not complete quackery: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.1...

A research paper makes use of multiple sources of known provenance and various degrees of authority and relevance. It tries to establish a consensus of knowledge, as close to fact as possible. The phrase "research suggests" is an appeal to authority that implies some kind of academic rigor. A theory paper, which is still useful and important, can be published without any kind of authority. You can just make things up.

That is what is called research in theoretical fields. Making hypotheses up and then proving implications of those hypotheses. In this case, it yields a falsifiable test: the theory claims the universe should have small positive curvature.

Would you say Einstein was not a researcher?

Ωₖ = 0.0007 ± 0.0019 (68% confidence level)

If the universe is curved dark energy is still a problem because the expansion is getting faster and overcomes the current curvature bounds.

Expansion definitely creates some issues here, at longer time scales how do we deal with this?

There's a PBS Space Time for that (from three years ago)

https://www.pbs.org/video/could-the-universe-be-inside-a-bla...

https://www.youtube.com/watch?v=jeRgFqbBM5E

Will hacker news side with ChatGPT or real physicists? :D

Love PBS space time !

There was a youtube lecture I saw years ago that showed exactly what you'd see as you fell into a black hole and passed through the event horizon.

You'd see EVERYTHING that EVER crossed the event horizon. But critically, you'd see it EXACTLY as it was at the monent it crossed.

Sounds a bit crowded to me. Sounds a bit like I'd expect the big bang to look.

Found the lecture. Here is a link to the appropriate part: https://youtu.be/BdYtfYkdGDk?si=iNHi7N68DHxT-52-&t=3182

I thought you were supposed to get spaghettified and die instantly ?

At the event horizon of a large enough black hole, the tidal difference in gravity between your toes and head shouldn't be noticeable. There shouldn't actually be anything special about falling through the event horizon when looking at yourself.

Outside though, you'd see everything start to blue-shift. Things below you would blue shift back to normal, and the universe above you would blue-shift and speed up until you'd see the heat death of the universe. Anything falling in after you would red-shift again as it approached to match your "normal" rate of time. Critically this would include any light or other particles, so it might be very hard to survive.

No matter how fast you go or how weird the space time you are in, your local clock should still tick steadily to you, and you wouldn't notice anything weird.

> There shouldn't actually be anything special about falling through the event horizon when looking at yourself.

If you went in feet-first, you'd perhaps find it quite odd that your feet never seemed to cross the horizon, as they would have red-shifted so dramatically.

> you wouldn't notice anything weird.

Maybe you wouldn't notice that you never saw your feet cross, since you wouldn't have much time to ponder it before your head crossed as well, but at that point, you surely you would notice that everything below you is black, since all light (and everything else) is now destined for the singularity. That's the very definition of the event horizon. There wouldn't be any reflected light.

-Just watched the lecture again, and you wouldn't actually see the outside universe speed up.

> The black hole universe also offers a new perspective on our place in the cosmos. In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger “parent” universe.

What specifically is meant by interior? Does this mean “within the event horizon” or something else?

I thought the Pauli exclusion principle is why we have neutron stars, ie the degeneracy of a star results in the fusion of electrons and protons to form neutrons and emit neutrinos.

What is preventing the collapse in this case and results in a bounce?

I speculate that the big bang is/was fueled by all the black holes that existed and will exist, like a huge cycle where all the energy sucked into black holes converges at the same point in time causing the big bang.

Fractal Universe - I discussed the idea with Benoit Mandelbrot back in '84 over beers, interning for him, before he'd published "Beauty of Fractals."

Cool anecdote!

How do you deal with Hawking radiation?

Maybe with space expansion? With more space, particles interaction is weaker overall. So the whole system kind of loses total energy.

* Not a physicist so this is a really uninformed take

flip the direction of time and hawking radiation ""creates"" mass/energy inside a black hole (overall mass/energy is conserved)

> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).

> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.

Do I understand right, that this would mean that every formation of a black hole would result in a bounce?

> But how come Penrose’s theorems forbid out such outcomes? It’s all down to a rule called the quantum exclusion principle, which states that no two identical particles known as fermions can occupy the same quantum state (such as angular momentum, or “spin”).

> And we show that this rule prevents the particles in the collapsing matter from being squeezed indefinitely. As a result, the collapse halts and reverses. The bounce is not only possible – it’s inevitable under the right conditions.

Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?

Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?

Different exclusion principle. For neutron stars, it is the Pauli exclusion principle (IIRC) which creates neutron degeneracy pressure. Enough mass and gravity can overcome it forming a black hole. The article is talking about quantum exclusion which happens at a much smaller scale. I don't know much about it because that exceeds the limits of my degree.

>Then how comes the neutron stars collapse into black holes despite obeying the exclusion principle?

One of the ways to overcome one of the levels of this degeneracy pressure is electron capture which is the opposite of a kind of beta decay. Squeeze hard enough and a proton combines with an electron to form a neutron and a neutrino.

But there are several proposed levels of degenerate matter in neutron stars, the idea being that one (final?) level of this degenerate matter is dense enough to make an object smaller than its schwarzschild radius. Uncertainty is high because we have no current methods to observe any of this kind of matter.

What goes on inside the schwarzschild radius is another mystery we don't have answers from, but there are lots of ideas with various levels of legitimacy.

Quantum physics in and around singularities or things we think are singularities is not understood.

Is it because the black hole is a macro distortion of spacetime and not a local quantum property?

With enough mass, there is enough energy from gravity to put all fermions into different states, so the collapse continues

Are you suggesting that the authors’ “bounce” would only happen if the energy was not enough to put them into different states?

This was an interesting read, but I didn't understand exactly what leads to the big crunch. I get the exclusion principle leads to pressure, and this causes the bounce, but why would it continue to accelerate and then decelerate resulting in a big crunch?

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.1...

I don't understand where the rest of the parent universe is if all of the matter has emerged from the event horizon. Twisted into a new dimension, perhaps?

My take away was that it's still somehow causally disconnected from our universe. They make an assumption that the space outside is empty and that makes the numbers correspond closely with observations. Maybe there is stuff there but very very far away?

Interesting sci-fi plot device but seems far-fetched, not gonna lie. To think that our highly stable universe is just compressed mass of another universe is a lot to take in. Does that black hole emit Hawking radiation as well and shouldnt our universe lose mass in result? And how exactly can our universe expand if the size of the black hole is fixed?

Well, at least it does make for interesting conversations. Someone will surely milk it for Youtube content.

This has been one of my pet theories for a while.

https://news.ycombinator.com/item?id=39271752

I love that theory. I very much spent time thinking that it would be cool if we were inside a black hold after reading A Brief History of Time.

Would it possibly make sense for a black hole in our universe to lead to a higher level "parent" universe? Or would any black hole universe contained within our own universe necessarily lead to a lower level "child" universe? Basically, I'm wondering if there's a way (within the constraints of this model) to access the parent universe.

Wow, wild this is being taken seriously now perhaps, I first encountered the idea in The Life of The Cosmos ~26 years ago[0] and my impression was the author, Lee Smolin, didn't REALLY beleive it, but he came up with it mostly to have some kind of preferable, falsifiable(er?) alternative to string theory, which he disliked even more, and perhaps more as an idea of the kind of theory we need to explore to start making progress... or that's my memory/impression form 26 years ago, I've been meaning to re-read it for a while since. Anyone read more recently/have other impressions?

(the basic idea was fecund universes/cosmological natural selection[1], such that we should expect to find ourselves, if the theory were true, very near to a local maxima of values such that they approximately maximize the number of black holes produced... but most of the book is really taken up with a fascinating look at the history of physics and ideas...)

[0]https://en.wikipedia.org/wiki/The_Life_of_the_Cosmos [1]https://en.wikipedia.org/wiki/Cosmological_natural_selection

> Research suggests Big Bang may have taken place inside a black hole

The title's use of the word "research," and the paper's content, suggest the idea resembles science more than speculation. But in fact, the paper has no observational evidence, nor a proposal for acquiring evidence, to distinguish it from other similar speculations.

To put it simply, at the center of a black hole is a singularity, a domain where existing theories can offer no guidance. So a new idea about singularities -- about black holes -- should suggest a testable property, to distinguish it from other similar ideas.

I say "idea" here to avoid use of the term "theory," which in science requires observational evidence to move past the realm of speculation.

Don't get me wrong -- speculations have an important role to play in science. But tendentious phrases like "research suggests" wrongly imply the presence of something more than speculation.

I've always liked the Idea that black holes accelerate matter faster than light behind the event horizon propelling it back in time creating a singular white hole at the first moment.

There are many many reasons why this is a dumb idea and it's just as much of a paradox as any other naturalistic creation theory.

stupid question: if at the beginning of the universe (before the big bang) all the matter was in the very same spot, shouldn't this have been effectively been a black hole due to the extreme density? if so, how could it explode if nothing can escape a black hole?

Black holes may contain a second event horizon in the center, like a Poisson's spot. So it was the Big Rip, when this spot was born.

That's not a stupid question. But I suggest reading the linked article which pretty much covers this.

This brings to mind something I keep thinking about for years (mostly from watching too many physics videos).

- Gravity "slows" the time down, gravitational singularity should bring the time to a halt

- Suppose there is a quantum process that makes the true singularity impossible, so all black holes immediately expand right back

- Looking at it from our time scales, even if the singularity existed for a moment, it would appear that "infinite" time has passed while from the black hole's perspective, the expansion was instantaneous.

- From earth's perspective, if the singularity ever existed in a black hole, it stands to reason that when the time "resumes" from a black hole expansion, it won't fall into any of our known timelines since infinite time would have passed.

Along those lines, makes me wonder if the "bang" is in fact the fact that after the time compression, all matter/energy is effectively arriving at the same point all at once.

Assuming our universe eventually collapses into a few black holes, perhaps the spawn of a new universe is simply all the matter and energy of our universe arriving at a new point in... time? an infinite amount of time in the future.

Also, really mind bending to think the universe may just be an infinite series of black hole explosions with no beginning. It is because it always was.

If this is true it almost literally means black holes are a way for universes to make children. If we apply Darwin’s principles of the strongest survive this must mean that universes that produce the most black holes are the “best”. If correct, what does this actually mean?

https://en.wikipedia.org/wiki/Cosmological_natural_selection

https://theeggandtherock.com/p/the-blowtorch-theory-a-new-mo...

Darwinian logic requires a feedback loop. And because those universes are isolated then there’s no “incentive” of a universe to have more “offspring”?

There is a theory of cosmological evolution. The child universes have slightly different physical constants and universes that produce more black holes will leave behind more offspring universes so over many generations, the universes evolve toward parameters that favour black hole production.

That's what Blowtorch theory predicts, it notes three stages of black hole formation:

- direct collapse after the big bang. Those supermassive black holes now from the center of galaxies and are the earliest and simplest form of how universes reproduced

- stellar collapse, requires the formation of stars, but those can be much more plentyfull than previous supermassive direct collapse black holes, so many more universes will have those

- black holes created by technology. Since black holes are incredibly efficient at converting mass to energy, in a universe that has the capability to form intelligent life, this life will eventually find a way to harness black holes as an energy source. In doing so they would create even more tiny black holes (maybe to power spaceships?), so such universes would form the most offspring.

It requires imperfect reproduction where the imperfections alter the probability of further reproduction.

If each black hole in our universe contained a pocket universe with very slightly different laws of physics (to each other and to us), but the same amount of mass-energy on the inside as our universe had when it started, then (1) those pocket universes able to create stars and black holes would also go on to create black holes with pocket universes, but also (2) those pocket universes not able to create black holes, would not create more pocket universes.

I have never seen a reason to think that this could happen, nor why such pocket universes might have more mass on the inside than they appear to have on the outside, but that's the argument.

These type of 'theories' I dislike only because they don't get to the root of the problem.

It is the same for 'multiverse' where that is used to explain literally anything 'it's like that in this universe but not the others'.

Sure, we can get creative and explain the Anthropic Principle by mentioning the multiverse.

But none of this answers how something comes from nothing.

Not the vacuum of space and its 'quantum foam' where particles jump in from nowhere.

Because that's not 'nothing'.

One of these nothings ... such as level 9. No possibilities.

https://closertotruth.com/news/levels-of-nothing-by-robert-l...

I won't touch level 8/9 nothings, other than to say I don't think they're coherent. But I am of the metaphysical camp that thinks there will be at least some small ground truth which physical law or object which cannot be reduced, an axiom of nature. Physics unfortunately will probably always be limited in distinguishing between basic facts which are truly irreducible, and those which are simply limits of our observational abilities. That's the thing that bothers me; even if there were a single beautiful law of nature that just IS, one which we actually manage to postulate based on evidence, we will never know for sure. GR definitely has a beautiful mystique, it's a shame that it's most likely just a mathematical approximation.

> But none of this answers how something comes from nothing

Why do you assume there was nothing?

I've heard about interesting theory. Since we observe large early galaxies, to explain them scientists postulate that they must have grown very quickly. But recently some scientists calculated how much light would such quickly growing galaxies could have emitted. And it turned out that this light after being dispersed by the dust and redshifted by the expansion of the universe it should have contribute to CMB, up to 100% of it's observed intensity. What's interesting they didn't make any assumptions outside of established modern cosmology. Just So it's entirely possible that CMB is something completely different than what we believed.

I still don't understand from the article why the bounce effect results in an accelerated expansion of space time. Is the black hole (our universe) in the parent universe getting bigger? And why is that non linear?

I've always had this idea that perhaps the whole universe had already collapsed into many black holes and perhaps each galaxy was actually formed via hawking radiation. Then our galaxy came out of Sagittarius A*.

So the expansion comes from the bounce. And we are in a dormant supermassive black hole of sorts. How would it look like in our world if the mother blackhole is actively gobbling up matter from the parent universe?

Why does it always have to by “hyperbolic” instead of parabolic?

I didn’t understand whether the author is implying that this happens to all black holes or whether the model only applies in some circumstances.

I definitely didn’t understand whether this is suggesting that expanding universes can be contained within black holes that look like fixed-size finite objects from the outside.

And what happens to the inner universe when the parent black hole evaporates through Hawking radiation?

The heat death of the inner universe.

I'm curious on what is "at stake" with this? The close lists a couple of predictions that this can lead to. I'm assuming they will be important in a far future time? Or do these help with some more near term problems?

Edit: I hasten to add that I'm not asking to undermine the research. Seems the more the merrier, there. Genuinely curious on what some of this could lead to.

Which suggests that:

1. You can have black holes inside black holes.

2. Potentially each black hole is a universe - although some are much smaller and less interesting than others.

[dead]

Hmm... What if some matter falls into our black hole? I know there are some weird time-space effects on the boundary, which I do not have any intuition about. To my knowledge it may be, that it will never fall in our time frame, or that it have fallen all already. The question is, will we able to see and welcome new matter entering our Universe?

I may be wrong, but I believe spending time in a deeper gravitational well means you observe everything outside of the well to be happening much faster; at the singularity, the entire future of the parent universe will appear to you as happening all at once. There is no notion of “matter that falls in later” — once you reach the singularity, you travel to the end of time in the parent universe. And the passage of time in our universe isn’t a continuation of time in the parent universe; it’s not even the same dimension, the latter is collapsed.

Thank you! That answered my question whether there would be in our universe a "white fountain" spitting matter coming from the back hole in the top universe. In your hypothesis where we lose one dimensione over the top universe than all the events of the top universe, like the mass arriving, happen in our universe all at the once in the beginning (the big bang).

while it doesn't take away from the article, i find it worrying that it seems mostly written with chatgpt

"This is not just a technical glitch; it’s a deep theoretical problem that suggests we don’t really understand the beginning at all."

"The bounce is not only possible – it’s inevitable under the right conditions."

ugh

There was a physicist who made a video making fun of crackpot theories from engineers and reading the comments we're all happy to put forth our completely unsubstantiated opinions with zero understanding of the math and observations involved

What would happen if beings living outside of our 'black hole universe' threw an object into the black hole, and thus into our universe? Would the object appear at the edge of our universe, or would some physical law prevent this from happening?

as we approach the potential singularity, the size of the universe changes as a (hyperbolic) function of cosmic time

Glad to hear that. I'm looking forward to any theories how to convert time to space (and back) ..with orthogonal universes/singularities ?

Does this model predict the CMB peaks?

I think this is a great summary. It's quite intuitive and elegant. Does anyone have any information about what the author's peers think of this model?

I'd love the idea that we are living inside a black hole, which is inside a black hole, which is inside a ...

The big bang sounds like how a computer would interpret being turned on.

Anyone else think this is what happened?

Nope, it's just you applying the thing you think you know to something you don't know.

Computers refer to this as 'the Big Boot'.

One day someone's going to reboot that computer and I'm going to lose all my carefully curated trauma.

Imagine a being inside a turing machine wondering what came before it was turned on... implying the turing machine is even on and we're not just looking at the set of all possible rule sets on a similarly abstracted mathematical chart.

[dead]

[dead]

So, the whole thing is a recursion, and the only thing left to see is how deep is the stack.

Notebook LM version https://notebooklm.google.com/notebook/bb55f273-a5e8-461a-b7...

Cool article!

I can hear Sean Carrol saying, though, that:

1. We know general relativity isn’t complete, because it doesn’t take quantum mechanics into account.

2. We can’t say whether this is right because we don’t know the quantum theory of gravity.

But I don’t actually know what I’m talking about.

So if our universe is inside a black hole from a parent universe, does that mean every black hole in our universe contains its own child universe? We could be living in cosmic Russian dolls all the way down?

Reminds me very much of Blowtorch Theory that was discussed here recently

https://news.ycombinator.com/item?id=44115973

it is funny the fact that author decided to explain who Galileo was

I haven't read the paper, it's probably well beyond me, but I have always felt that the presumed existence of a singularity had to be the result of incomplete theory.

How is this differnent from Dr Nikodem Paplawski's tortion theory of the same?

It was featured on Event Horizon (john Michael godier)?

give us one free miracle and we'll explain the rest

Bertrand Russell is the pope

I sympathize with Lee Smoolin's cosmological natural selection hypothesis, which would require that black holes give birth to new universes within

I can’t beleive you and I are the only ones familiar with, and that no one else referenced or responded to this connection! https://news.ycombinator.com/item?id=44251438

I too read the book and was just searching for anyone mentioning it. Why can such an idea be called new, when someone else already described it decades ago?

Very high "Time started when someone clicked start" - "cool, how did events happen before they clicked start?" factor title.

As a lay reader, it sounds like they are assuming what they are trying to prove.

Yes, it produces a testable prediction, but seemingly based on a mathematical assumption derived from our observed cosmic radiation background.

> This lower bound follows from the requirement of χk≥χ∗≃15.9 Gpc to address the cosmic microwave background low quadrupole anomaly

As a lay reader, can I assume that no scientist would publish a theory with mathematical circularity (at the heart of the prediction)? I sure can't verify it myself.

If universes can exist in black holes and obviously black holes exist in universes, doesn't that smell like infinite recursion?

What reason do we have to believe that every universe can support black holes? We only have a sample size of 1 here.

What reason do we have to believe that there is more than one universe?

Black holes all the way down

This theory actually makes sense. Vs big bang where half of the theory is “let’s assume that there is this thing that explodes”

Wouldn't it have to be a black hole anyway given how much matter was concentrated in a small point?

Great! Maybe the idea of a cyclical universe will gain traction.

In my view, there is one universe. We are in it. It cycles from maximum to minimum condition endlessly. This cycle is much longer than any entity lifespan and for any entity, the current state is THE state for them, and all they will know and become.

What does it expand into?

Nothing. Space itself just gets bigger and smaller over time.

No beginning, no end. It all just is.

Research? Sounds more like speculation.

Don't suppose you read the paper..?

It's probably best not to jump to conclusions until we see it replicated in another universe.

I thought this was already an old general idea; that each black hole ignites the birth of a new universe?

So that's what that big blob in the Mandelbrot set is. It's a diagram of our fractal universe.

Could a computer simulation also contain another universe, with virtual black holes that have universes?

Can a computer simulate itself?

https://www.youtube.com/watch?v=92WHN-pAFCs

Big bang theory no longer excites me. As long as we can't explain consciousness all these theories are pointless. All theories mere appearances in consciousness including the universe and everything we experience.

Consciousness has the property to render infinite universes and theories.

But we have no clue how universe creates consciousness.

Consciousness is a specific biological adaptation which is primarily focused in the management of social relationships, status, and the prolonged adolescence of children. (and their required care)

There's no reason to think that consciousness is an important question in the objective sense; it just matters to people. (and rightfully so) People wondering about consciousness in the universe might be akin to dogs wondering what the big bang smelled like.

Are we both talking about the same thing?

https://en.m.wikipedia.org/wiki/Consciousness

What is an important question in the objective sense? Is life, or no because that just matter to life? It seems oxymoronic, "objective question", "objectively important".

I don't follow GP's sort of solipsist (?) take, but would say question of whether big bang took place in a black hole is pointless compared to life/experience and how they arise.

Solipsism is the question whether it's all made up by my mind and only my mind exists.

I am not interested in that.

I am interested in the thing in which all the made up stuff appears. And the thoughts and mind appears. Even I appear in that.

Seems like someday we will prove that if you get enough neural like things organized in a structure similar to ours or some mathematical similarity thereof that consciousness automatically arises like mixing certain elements to get a compound but in a vastly more complex manner

First define consciousness such that the definition differentiates you from a computer with a webcam.

You cannot define consciousness. You can only experience it. In fact consciousness is the only thing you will ever experience.

Perhaps you should use 'sentience' or something more precise to mean 'qualia-experiencing'. The word 'consciousness' is quite overloaded and thus trips people up who haven't thought about this as extensively as you have. In particular many people take it to mean "self-awareness" (whether correctly or not), but it seems obvious to me that there are many sentient beings which lack self-awareness but still have an internal experience.

Yes. Self awareness is just another content inside consciousness.

You can measure various aspects of a computer. You can't measure consciousness.

That's not a definition. Depending on the definition, it may be possible to measure it.

You cannot measure consciousness. You are consciousness thinking of itself as the human. Measurement is an event appearing in consciousness done by humans.

It's like persons inside GTA talking about measuring the Samsung monitor. It makes no sense cause they can never see the monitor or locate it. They appear in the monitor.

You absolutely can measure "various aspects of consciousness" -- for example, "how much of the last 24h has this consciousness been awake" seems simple. So your definition seems kind of weak, could you be more precise?

Conversely, in your definition, is consciousness the only "thing" that you would describe as not being able to measure various aspects about it? Are there any other objects or concepts which you also cannot measure various aspects about? If yes, what differentiates those things from consciousness?

So what if one of the numerous black holes in the universe starts to bounce?

We are inside of a Docker container.

Sean Carroll says this is absolute nonsense: https://youtu.be/U3uIiv48q98?feature=shared&t=6046

natural selection obviously operates at the level of universes

I've spent the past month or so immersed in Penrose diagrams. Some of the implications of the math and diagrams include white holes (opposite of black holes - spew matter outwards), infinite universes contained within one another other, anti-gravity universes, and things like this. You can also fall into a black hole and make it out into another universe instead of meeting the singularity (at least, an idealized, rotating black hole). Anyway, cool stuff.

Science today:

{..insert here a statement...} maybe yes but also maybe not {...clickbait things here...}

> Research suggests Big Bang may have taken place inside a black hole

Is this OnlyFans ?

my feeling is that the beginning of the universe is so unbelievably unexplainable and strange that we will never truly understand its origin

>We are not special, no more than Earth was in the geocentric worldview that led Galileo (the astronomer who suggested the Earth revolves around the Sun in the 16th and 17th centuries) to be placed under house arrest.

Wow - like this anti-humanist prejudice is totally 1993. And not in a good way.

two-photon collision experiment has permitted humans to hypothesize a simpler explanation to the beginning of the creation of more electromagnetic forces, which obviously behave differently than how are bodies were designed to receive them i.e. evolutionary biological bandwidth...

Do we live inside a black hole?

TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.

1. Motivation: The Crisis in Fundamental Physics

Modern physics, despite its immense successes, faces deep unresolved problems:

The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."

The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.

The lack of a unifying principle that can reconcile the fragmented domains of current theories.

TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.

2. Ontological Foundations: Radical Relationalism

Core Postulate:

"All that exists is relation."

There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.

The universe is fundamentally non-separable: no part can be fully understood in isolation.

This principle generalizes quantum entanglement to a universal ontological status.

Realism and Symbiosis

Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.

The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.

3. Mathematical Formalism

3.1. From Discrete Relations to Emergent Fields

At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.

At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.

The emergent metric is given by: g_{μν}(ϕ) = e^{2αϕ} η_{μν}

The Symbiotic Action is:

S[ϕ]=∫d4x−g(ϕ)[12gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]S[ϕ]=∫d4x−g(ϕ)[21gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]

where V(ϕ) is the relational potential.

3.2. Dynamics: Coherence, Dissonance, and Self-Organization

Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.

The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.

When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.

3.3. Quantization and Emergence

TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.

The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.

4. Phenomenological Implications

TARS provides new perspectives and solutions to major physical puzzles:

Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.

Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.

Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.

Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.

Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.

5. Scientific Achievements to Date

Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.

Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.

Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.

Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.

White paper and technical documentation: Comprehensive and available for peer review.

6. Meta-Theoretical and Interdisciplinary Reach

TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.

7. Conclusion

TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.

Asimov already covered this in The Last Question: https://users.ece.cmu.edu/~gamvrosi/thelastq.html

Not really. Asimov's story did not represent the process as a mathematically inevitable consequence of physics. It might not even have gone through a second cycle. Cellular life, dollars, and teletypes would all have had to come about again. (-:

[flagged]

You're missing the part where the robot was created by us.

Wow, that makes it even dumber. That idea was literally also in Genesis as the original sin of man: "You shall be as Gods."

Edit, for posting too fast: I don't consider the response below to be in good faith, for if there is a God, nothing could be more offensive than to deliberately try to knock him down a few pegs to be "plausible"; while considering the Big Bang to be "plausible" because that doesn't count as "fantasy style magic."

You're being downvoted for a bad read of the material. Any comparisons to God are intentional and deliberate - but mostly serve to knock God down a peg or two by grounding it in something plausible instead of the faith based miracles and straight up fantasy style magic from the Bible.

Futurama has a great episode where Bender meets God (who has merged with a computer) that tackles similar themes.

If you find this to be a harsh reaction, maybe consider how the wording of your initial comment is an effective provocation to anyone who doesn't share your belief system.

[dead]

[dead]

When I first heard the idea that our universe began inside a black hole from another one, it felt like something out of a sci-fi movie. But the more I sit with it, the more it starts to feel like the universe is quietly nudging us, saying it has a much bigger story to tell.

If the Big Bang was just a moment in someone else’s universe, then maybe everything we know is just one chapter in a book far larger than we can imagine.

[dead]

[flagged]

There are countless versions of this theory out there. Basically, a universe existed, then collapsed down to a single point, and then expanded again (the big bang). Rinse and repeat.

In this version we're still inside the black hole.

"Tau Zero" by Poul Anderson

Is it the same universal every time? If so, see you later alligator.

Or a universe expanded inside a black hole and we are holograms on the shell.

[flagged]

"Nothing" implies that something exists, this duality creates the universe.

There is no proof of "nothing " existing. Every observation we take, we see "something".

Than why do we need a beginning if there was always something.

Strictly speaking, modern cosmology does not treat the Big Bang as the beginning of all of existence, it's what happens when you take observations about large scale cosmology and run them backwards in time.

Based on the information we have available about our universe, we can't make predictions or formally model anything prior to a certain point in time, consequently it's convenient to treat this moment as the earliest point in time in which physics as we know it makes any sense. So while there may have been some kind of existence prior to the Big Bang, we have no way to make sense of it even at a conceptual level. Given that, we may as well treat this special point in time as the beginning of the universe as we understand it and can explain it using physics, as opposed to some absolute beginning of all of existence.

Thank you for your insightful response.

We don't. We never see the "beginning" of anything. All we observe is things that are already here changing.

My lay interpretation of this theory is that it says there was no beginning.

But a cycling of a previous universe.

I was a little unclear on the ending, where he says this theory would place our entire universe "inside" a black hole of a parent universe.

All in all, it does seem to tie up some loose ends, and suggest some order to what previously required speculation.

We don't. There was never nothing, because there is no "before" the big bang. Time as we know it did not exist until the big bang. It's not there was nothing, it's that there was no there or then.

There is as yet no proof that there was nothing before the big bang, it's just a supposition. The hot dense universe definitely happened but whether that was the "beginning" is essentially unknown.

"beginning" is a misnomer, since time itself started with the Big Bang. There is no such thing as "before" the singularity, as time and space were curved together.

Time is a map of the states of consciousness, I believe consciousness/awareness of the universe has no beginning just infinite layers of abstraction.

This is meaningless technobabble.

I'm happy you feel that way

There are many theories that portray time as existing before the big bang.

Well, do the calculations of how long it takes for all mass to move around in the initial moments of the big bang. You'll realize that the closer one gets to the singularity, the slower time passes due to time dilation, which means that you'll get the whole eternity to reach the singularity. It only looks like a few seconds from our point of view, looking at the big bang.

We don't need it, the same way we don't "need" scientific proof about anything. We could live our whole life pleasing the stakeholders and be happy about it

For the same reason the mind seeks for an ending if there is something. It’s the environment our little neural nets trained in.

Only if something exists. But both nothing and something could not exist, and then there is no duality, just nothingness without a something to relate it too.

The concept of Nothing can only exist if Something exists, they both exist and are the substance that make up the universe.

That’s a boring axiom.

Nothing is everything

Everything is everything

[flagged]

[flagged]

[flagged]

Coping with the meaningless splendor of the universe is daunting, but I will do my best!

[dead]

That's the whole point of studying this, which you reject. Let us know why your gut instinct is better. Show us your research.

There's nothing wrong with studying science. What's silly is throwing away other valid sources of information and pretending they fall under the responsibility of science.

More info available.

TARS is a new theoretical framework that fundamentally reimagines the foundations of physics. Instead of assuming that reality is made of pre-existing entities (particles, fields, or spacetime itself), TARS posits that everything that exists is, at root, a relation. In this view, the universe is a dynamic network of coherence relations, and what we perceive as space, time, matter, and even physical laws, are emergent phenomena arising from this underlying relational web.

1. Motivation: The Crisis in Fundamental Physics

Modern physics, despite its immense successes, faces deep unresolved problems:

The incompatibility between General Relativity (GR) and Quantum Field Theory (QFT)—the so-called "quantum gravity problem."

The mystery of singularities (in black holes and at the Big Bang), the nature of time, and the unexplained phenomena of dark matter and dark energy.

The lack of a unifying principle that can reconcile the fragmented domains of current theories.

TARS responds to these challenges by proposing a radical ontological shift: relations, not entities, are fundamental. This shift is not just a new model, but a new grammar for describing reality.

2. Ontological Foundations: Radical Relationalism

Core Postulate:

"All that exists is relation."

There are no absolute, isolated objects. The very identity of any "entity" (particle, field, law) is defined by its pattern of relations with all others.

The universe is fundamentally non-separable: no part can be fully understood in isolation.

This principle generalizes quantum entanglement to a universal ontological status.

Realism and Symbiosis

Symbiotic Realism: Entities and their properties are co-constituted through mutual relations. There are no intrinsic properties, only extrinsic, dynamically co-created ones.

The observer is not external, but an active node in the relational web. Knowledge itself is a process of coherent participation in this network.

3. Mathematical Formalism

3.1. From Discrete Relations to Emergent Fields

At the most fundamental level, reality consists of discrete coherence relations, denoted ξ_{ij} (or quantum operators ξ̂_{ij}), between abstract nodes.

At emergent scales, these relations manifest as a continuous coherence field ϕ_{μν}(x), a symmetric tensor field encoding the density and structure of relational coherence at each emergent spacetime point.

The emergent metric is given by: g_{μν}(ϕ) = e^{2αϕ} η_{μν}

The Symbiotic Action is:

S[ϕ]=∫d4x−g(ϕ)[12gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]S[ϕ]=∫d4x−g(ϕ)[21gμν(ϕ)(∂μϕ)(∂νϕ)−V(ϕ)]

where V(ϕ) is the relational potential.

3.2. Dynamics: Coherence, Dissonance, and Self-Organization

Local coherence (ξ_l) and global coherence (ξ_c) quantify the degree of relational compatibility.

The difference Δξ = |ξ_c − ξ_l| acts as a "relational tension," driving the system toward higher global coherence.

When Δξ exceeds a threshold, critical reorganizations occur (mediated by an operator F₀), leading to emergent order, the arrow of time, and the formation of physical laws.

3.3. Quantization and Emergence

TARS aspires to a quantum theory of relational fields, where quantization applies to the relations themselves, not to fields on a pre-existing spacetime.

The challenge is to mathematically derive how spacetime, matter, and interactions emerge from the dynamics of ξ̂_{ij}.

4. Phenomenological Implications

TARS provides new perspectives and solutions to major physical puzzles:

Singularity Resolution: The regularization of black hole and cosmological singularities emerges naturally from the relational dynamics.

Dark Matter/Energy: Gravitational anomalies are interpreted as regions of relational coherence deficit, not as unseen particles.

Inflation and Cosmology: The early universe's rapid expansion is modeled as a phase transition in the global coherence field.

Black Hole Evaporation: Predicts a slower, non-singular evaporation process, leaving stable remnants.

Consciousness and Life: Interpreted as high-order reflexivity in relational networks—consciousness is a self-referential coherence loop.

5. Scientific Achievements to Date

Full mathematical formalism: Action, field equations, emergent metric, and relational potentials.

Analytical derivations: For black hole interiors, dark matter effects, and cosmic inflation.

Numerical simulations: Demonstrating the propagation of coherence fronts and self-organization.

Distinct predictions: Such as black hole evaporation profiles and singularity avoidance, differentiating TARS from standard models.

White paper and technical documentation: Comprehensive and available for peer review.

6. Meta-Theoretical and Interdisciplinary Reach

TARS is not just a new physical theory; it is a meta-framework for understanding emergence, organization, and knowledge itself. Its principles can be applied to biology, neuroscience, social systems, and artificial intelligence, wherever complex relational networks give rise to emergent phenomena.

7. Conclusion

TARS offers a radical, mathematically grounded, and phenomenologically rich alternative to current foundational physics. By shifting the focus from entities to relations, it provides a unified language for the emergence of space, time, matter, and law. Its predictions are testable, its formalism is rigorous, and its implications reach far beyond physics, offering a new way to organize scientific and philosophical knowledge.

"In my room, redefinin' the meanin' of black holes"

- Earl Sweatshirt

I went to school in a very bad neighborhood. Once I was sent to the office because my math teacher asked me what I was reading about that was soo much more interesting than our textbook. I happened to be reading "A Brief History of Time", so I answered "black holes."

At the time I couldn't understand why my dad laughed about that particular phone call from the principal.

Hahahahahahahaha

Maybe it was the repeat.

I always pondered about everything in our universe getting swallowed up continuously merging black holes until all of a sudden "everything" is "in" the black hole and then suddenly that's your big bang, and everything starts all over.

I don't have the Ph.D physics/maths skills to work out the plausibility of any of that (or variations on that) but I've always felt I've been good at coming up with ideas.

Any physicist wants to work with me, I'm https://purpleidea.com/contact/

Isn't time a human invention useful to model the nature? It's literally just a defined interaction as a reference, i.e. the sun rising up and going down which is the rotation of the earth.

So IRL there's no time, there's no need to have a beginning or an end. Whatever happened when all the matter was close together isn't the beginning of anything, just a phase.

Not true. The arrow of entropy has a direction and it's the same as the arrow of time. There's not a good explanation for why though.

There's a perfectly good explanation for why though, in fact the explanation is what motivated the formalism of entropy to begin with. There are significantly more ways that the energy contained within a closed system can spread throughout that system than there are ways for energy contained within a closed system to condense, so that if you observe the state of a system at two different moments in time, you will expect to see it evolve towards the statistically more likely outcome than the statistically less likely outcome.

And from first principles, that's what entropy is, a measure of how energy is dispersed throughout a system. Of course once you have that first principle understanding of entropy then you can come up with more rigorous formalisms to properly quantify what it means for energy to be distributed throughout a system, such as measuring the number of microstates that correspond to a macrostate, and other various formalisms that are more or less equal to each other... but fundamentally they all start from this basic principle.

If time were running against the arrow of entropy, nobody could perceive or measure it, right? Remembering something is per se an increase in entropy, so the universe could run in negative time direction, but we would simply forget, what had happened.

That said, I personally think such thought experiments are futile and the nature of time has to be understood by its connection to causality and information.

Of course you could perceive it, measure it and record it. The entropy of your body or your brain is not necessarily increasing, nor is the entropy of your computer or other information storage systems.

Entropy only statistically tends towards an increase in closed systems and neither your computer or your brain are closed systems. They are both constantly getting energy from an external source of power and in turn dispersing previously consumed energy out into their environment.

And yet you still manage to perceive things just fine... in fact your perception of the world is unlikely to change whether or not the entropy in your brain increases or decreases by some bounded amount (of course too much of either an increase or decrease will destroy your brain).

Your claim about remembering an event, which likely alludes to Laplace's demon [1], requires an overall increase in entropy in the system as a whole, but does not require an increase in entropy in the specific part of the system that is recording the event.

Every time your computer calls a function like memset(dst, 0), or sorts a list, or arranges data into some kind of structured binary tree, your computer is decreasing its own internal entropy by taking a statistically likely arrangement of bits and transforming it into a very unlikely arrangement of bits. The decrease in the internal entropy of your computer is more than offset by an increase in global entropy but that global entropy is radiating way out into the cosmos and has no impact on your computer's ability to register information.

[1] https://en.wikipedia.org/wiki/Laplace%27s_demon

There's no arrow of entropy, it's an invented useful model to describe something that nature does. Everything is like that, I.e. there's no electric field, it's a useful way to do calculations about particle interactions.

Of course these are models. And to be able to recognise that entropy increases with time is an example for their usefulness.

Does it increase over time or does it do its thing and in our model we decided that stages of it is called time?

Right, i had the same thought. What we can say is, that the quantities we call t and S are correlated.

Absolute entropy of a system is calculated either by integrating heat capacity/temp at constant pressure from 0kelvin to the measured temperature, or by calculating via Shannon's method using average amount of information in a discrete random variable.

There is no time factor in any absolute entropy equation.

Empirically, if you measure the entropy of a closed system at a given time, and you measure the entropy of that same closed system at a different time, then calculate the deltas of each, their signs match so long as the time delta is finite and the system isn't empty. So stated plainly, as time increases, so does entropy.

By combining these first principle formulae with the empirical results on entropy, you arrive at the second law of thermodynamics. However, like I said before, we're not really sure why the signs match and it's considered to be an unsolved problem in physics.

https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_p...

We have no idea if there is a meaningful beginning or end, other than heat death. But time is real in the sense that there is an arrow of time, due to entropy.

No, time is what the clock measures. Consciousness does not collapse the wave function meaning clocks exists without humans and time exists without humans.

Exactly, time is whatever the clock measures and the clock does it through some defined physical interaction. Can be a swing of a pendulum, can be vibration of an atom, flow of sand, unwinding of a spring etc.

It's useful because its quantifiable.

The second, however, is a purely human invention.

I'm butchering the mythology, but the Greeks had Cronos and Kranus. One was measurement, and one best explained as cause and effect.

The hot dense universe caused our current cool universe, and not the other way around, which makes the two states of the universe quite different.

Time is the coordinate of spacetime that has a different sign in the metric than the other three.

Try writing a computer program that has side effects without time existing.

What if it wasn't the beginning of our universe or wasn't the beginning of everything, including what is probably outside of our universe?

As I understand it (I‘m not a cosmologist by any means), saying that the observable universe began at big bang simply means that anything that happened before the big bang has no effect on what happens afterwards.

There may be other universes out there, with their own big bangs, but that has no effect on ours.

Reading this article, I think they are simply disputing the necessity of singularity inside a black hole, and hypothesize a universe which expands from non-singularity black hole, while staying inside its own event-horizon.

That is how I understood it at least, somebody please correct me if I misunderstood it.

Eh, the thing about the statement there is you're redefining "universe", which is fine, but restating a definition isn't really saying anything new. The literal meaning of "universe" especially with respect to the Latin origins is... well... everything. It may make sense for physics to separate in to separate sets of everything if there's some reasonable justification.

There's the Universe (everything everywhere everywhen), and then there's the observable universe. Most testable theories will be referring to the observable universe.

Beginning is an illusion created by our way of perception. Time is neither linear nor real so how can there be a "beginning"?

"Your honor, I could not have possibly shot that person, because yesterday might not have been before today, or at least, there is reasonable doubt that yesterday was before today, according to some physicists on crack. I treat those physicists with high regard personally though, and they have degrees that you don't have, so the court must reasonably conclude their opinions should be entertained."

I guess that's a joke, but it's actually kind of serious that causality, personhood, identity, free will, etc. are all social constructs.

They are useful to us, but every now and then it's helpful and humbling to remember it's a fiction we assign, rather than fundamental.

Criminal justice or the concept of culpability is one of these areas. I know I've seen material by Robert Sapolsky, a neuroscientist who does not believe in free will, talking about how off the mark criminal justice and punishment for crimes can be.

You’re stating this as if determinism has been proven beyond a doubt which is not the case.

I think it's unclear what kind of determinism you are presuming. Determinism in the universe? Determinism in consciousness? Certainly a deterministic machine can exist in a non-deterministic universe.

However I didn't just assume a lack of free will. I also assumed a lack of identity. Do you realize that who you are is socially defined? When you breathe in, the air in the room around you becomes part of you. When you breathe out, you lose certain gases. When you eat your food, similar story. There's a good case to be made that "you" are in the entire room or the entire food chain. That does make causality and culpability hard to assess objectively. When we do so, we do so subjectively.

Ah, so we’re playing at being shamans.

In that case I dub you a mushroom.

Don't be silly. I didn't say anything about shamans. I'm saying human existence is subjective. Culpability, like the courtroom joke above, is subjective. They're useful models for how the world works but it isn't objective reality.

We would do well to remember that every now and then. People who get too into pretending their perspective is objective reality tend to do stupid things.

Isn't identity exactly defined as what one perceives as part of oneself? Food becomes me as soon as I dis-member it to make it to be part of myself. Other food becomes you. This doesn't make food not within my sphere of perception a part of me; before digestion, it stays separate, like a virus doesn't become part of me -- the immune system acts a biological discriminator between what is part of me, and what is not. You are not me, and I am not you; we are physically attached to different matter. I understand people play mind games based on varying definitions of identity, but ultimately you will find that you have control over certain things comprised of physical matter, which then together with your mind makes up "you", and you're not in control of other things, which make them "not you". That's how I would say it is defined, after all. I am not in the entire food chain, because my perception and control simply doesn't reach that far. If I could control objects with my mind, it would be reasonable to say that they are a part of "my body", which makes them a part of me. If you use these language constructs differently, we lose the ability to communicate over them?

Seems like a long-winded way to say you suffer from anxiety.

> like a virus doesn't become part of me -- the immune system acts a biological discriminator between what is part of me, and what is not

But what about symbiotic organisms? What about your microbiome? Or the mitochondria, which began its existence as a separate organism? Or, they say our DNA includes many viruses that our ancestors contracted. A number of these things do stick with us and we sometimes even become totally dependent on them to function.

Exactly? I agree that identity is a fuzzy construct which includes socially constructed elements, and is not a fundamental "thing" that can be observed externally and then named "identity". I disagree that it is therefore "fiction"; as a concept, it is very real? My point was that I don't see how you can claim that identity is nonexistent ("lack of identity"), since the moment I use the term, I "create" and "have" it; it is a flexible enough umbrella to include the distributed system of my body, since I cannot exist separately from it? What "belongs to me" contributes to my identity.

To pick one possible simple and broad definition from WP, "Identity is the set of qualities, beliefs, personality traits, appearance, or expressions that characterize a person or a group." -- you made it sound like that set is empty, which doesn't make sense to me. My identity is part of "I". Every being has an identity; it's not something you can get rid of?

An interesting corner of philosophy for me is when people worry about perfect clones with all your memories. The only reason it bothers us is because we're not used to our doppelgangers turning up and claiming our sofas and relationships. In a polity where clones are commonplace and provision is made to inform the source and the perfect copy that their material possess will be divided or some stuff will be provided, the shock value would fade away.

That doesn’t affect time in the sense discussed here, though, which is a fundamental dimension in our physical theories.

It's been several years and I'm not fresh enough to summarize it, but some time ago I read Carlo Rovelli's "The Order of Time" which is a pop science book on why that isn't true. Ymmv. I'm sure many reading this know more than I do about the topic.

Carlo Rovelli's book is idiosyncratic, it doesn't reflect scientific consensus on the matter.

Care to give a specific example?

It’s more a philosophical book than a physics book. I’ve only skimmed it, but it presents philosophical views that don’t reflect a scientific consensus.

Let me strengthen the observation to say they are the “social constructs [most] useful to [those who survive] us.”

"Objection, your honor. In the many-worlds interpretation there is a world in which that happened."

Many-worlds doesn’t predict that everything happens somewhere; far from it.

Well, it's just a joke. :) It doesn't necessarily have to make a lot of sense.

In any case, I find your comment very interesting. I'm studying quantum computing at the moment, and I've had to read the different interpretations of quantum mechanics, including Everett's many-worlds interpretation. As a non-physicist, I've found the different interpretations fascinating.

The many-worlds one, as far as I understood it, says that all the possible outcomes of a quantum measurement actually "happen" in different worlds. I have the impression that you would be able to give a much better explanation.

In any case, in the joke the gun is shot in the macro world, not in a quantum state. It's possible that it is a quantum gun, but probably not.

Let's say "overruled" then.

The many-worlds theory says that the time-evolution of the (universal) wave function according to the Schrödinger equation is what's real. Different "slices" ("branches") of the wave function correspond to different "worlds". (A "world" is basically defined by what is quantum-entangled together.) The wave function thus decomposes into the different worlds.

Collapse theories, in contrast, state that at specific points in time (the "measurements"), the wave function stops following the Schrödinger equation, and instead collapses to a single slice/branch/world, thus upending the natural proliferation of branches implied by the normal time-evolution of the wave function according to the Schrödinger equation.

Even in many-worlds, however, the wave function doesn't necessarily contain all conceivable worlds. It only contains the worlds, following from some initial quantum state, that follow from the Schrödinger equation. While it's true that all possible outcomes of a quantum measurement become real (because they are all contained in the wave function in superposition), "possible" here means specifically what the equations allow, not any imaginable world.

Thank you for the explanation! Your comment has helped me with my Master's degree. The magic of Hacker News!...

I wonder how far counsel could take it before the judge hit them with contempt for lawyering while Nietzsche.

xkcd super soaker

Not many people these days like to hear this (I myself was one of them), but the answer to this is in Genesis.

There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.

The Hebrew name of God, YHWH, literally means "He Who Is." In other words, the Self-Existent One. The father and originator of all things that were, are, and will be, who exists outside of spacetime.

I understand that many people yearn for a religious explanation to answer the question of what caused the universe to exist. I myself am content with the "it just happened" explanation, as any information prior to the big bang, if it even exists, is unknowable.

There are countless other religions that believe in a deity who created the universe. These deities either created themselves, or had always existed outside of space and time. To that end, any one of those deities would be on equal footing with YHWH. I don't think that it is appropriate to axiomatically claim that a certain deity exists because only that deity could have caused the universe to exist.

Yet you call yourself a fool in your own username. Why be so sure you're not wrong about any or all of those statements?

It would be a nice argument for deism - but to jump from that into anything more, seems way too extreme of a leap.

Why Christianity then, over Hinduism? Why any human religion at all?

The Christian answer may be "God showed the 12, martyred, codified by church fathers [無]" but I haven't asked any Hindus, or anything nonhuman.

[無] https://en.wikipedia.org/wiki/Trinitarianism_in_the_Church_F...

This is not an answer that satisfies just begs more questions.

Who Created God? No one? Why does the universe need a creator if God does not?

Where does free will and evil come from if God is "originator of all things that were, are, and will be". For true free will to exist it must have a source of entropy which denotes something outside of Gods control and design otherwise everything is deterministic as set forth by God.

>There's a reason some of the most famous mathematicians, scientists, engineers, and philosophers of all time believe(d) in God.

That reason being that for much of Western history if you didn't believe in God the Church would burn your research in a big fire and probably you on top of it.

That explains nothing.

Neither does the precursor to the Big Bang. It's the same exact thing.

They are not the same thing. Religion and science may try to answer the same questions, but they are entirely different endeavors.

The idea that they're mutually exclusive is entirely stupid.

The trouble is we can strive to understand the physical circumstances we find ourselves in. Once we decide that the circumstances simply 'just are' because He Who Is, we no longer have an objective basis for discovering why things are as they are. There's no need, no purpose.

"An equation means nothing to me unless it expresses a thought of God." — Ramanujan

I like to think he was referring to computation. There's a reality to the constant pi, its computation, and ourselves and the representation being part of that same universe.

I think they mostly "believed" because they would be ostracized and maybe even killed for not believing in God and saying as much. Many who were famous in their lifetimes would have had enemies who would have loved to destroy them via that avenue.

Yes, not many people these days like to hear senseless drivel, hence the failing churches.

Have you visited a church lately? You might like it. I for sure, do!

I too like to read fiction, and play role playing games, occasionally. I just don't make real-world decisions based on the DM's chosen lore.

You're in Athens, son.