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

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

#531
post #322

Earlier quoted context omitted.

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.

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

#532
post #402

Earlier quoted context omitted.

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."

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

#533
post #515

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…

> requires a parent universe Not exactly . A universe can expand, slow down, then collapse. In this case, bouncing back out. 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 Yes and no. You're not thinking about contraction. With relativity we can fit a 100ft ladder inside a 10ft barn. Mo…

>> 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)

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

#534
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.

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

#535
post #51

Earlier quoted context omitted.

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

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

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

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

#536
post #61

Earlier quoted context omitted.

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 tha…

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 an…

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.

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

#537
post #515

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…

It's black holes all the way down!

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

#538

Earlier quoted context omitted.

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.

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

#539

Earlier quoted context omitted.

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 m…

>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 T…

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.

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

#540
post #515

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…

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…

> "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.

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