Research suggests Big Bang may have taken place inside a black hole
port.ac.uk757 points by zaik 5 days ago
757 points by zaik 5 days ago
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.
> 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.
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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.
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.
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.
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.
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.
> 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.
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...
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.
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.
> "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.
> 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.
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.
*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"
Where does the information of the previous universe before the bounce go? Is it destroyed?
Cosmic Background Radiation distribution could be that information. The distribution of mass hitting the event horizon then bouncing
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).
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.
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?
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.
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.
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?
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'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?
> 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].
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.
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
What's in a 1D black hole?
I'm guessing it'd look something like this on a 1-dimensional number line:
--- > | > >> . << < | < ---
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]...
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.
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.
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.
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.
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!
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.
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?
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.
> 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.
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.)
“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.