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Old 09-21-2018, 10:27 AM
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How plausible is my pet theory that our universe is inside a black hole?

I'm no scientist. I have done no special research.

But I have a pet theory (I might have read it somewhere) that our universe exists inside a black hole. It answers the questions of "what came before the Big Bang?" (the collapse of a star) and "what exists outside our universe?" (another universe). And it would seem to account for why all of the elements for life derive from stars (the ole' idea that "we are stardust").

And, it offers the tantalizing prospect of answering what it's like inside the black holes we see in our own universe. Yes, it's black holes all the way down (and fits with my other non-scientific science theory that the universe is teeming with life, although it is so damn big - or we are so damn small - that we have simply never encountered it. We're the proverbial ant hill in an abandoned parking lot wondering if there are other ants across the street in the grassy park - dude, ants are everywhere, but how can an ant even begin to conceive of all of those other habitats?)

While I enjoy my theory - what's wrong with it? Why is it eye-rollingly bad? What fundamentals am I missing?

Please debunk this theory.
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Old 09-21-2018, 10:38 AM
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I'm no scientists myself, so I'm sure someone more knowledgeable will have a better critique of your theory.

Something I see wrong with your theory is that our universe is expanding. If we were "inside" a hole, then it should appear to us the universe is contracting. And we still haven't addressed: Where did the universe come from that made the star that eventually died and became a black hole that somehow created this universe?

Your theory appears to be using circular logic.

Last edited by Grrr!; 09-21-2018 at 10:40 AM.
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Old 09-21-2018, 10:44 AM
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You may be interested in Lee Smolin's The Life of the Cosmos, in which he proposes the idea that the creation of a black hole produces a new universe, with fundamental constants slightly different than in its parent universe. This leads to a kind of cosmological natural selection, where the universes whose constants produce the most stars (and thus the most black holes) produce the most child universes. This explains why the constants in our universe seem specially tuned to produce matter.

https://en.wikipedia.org/wiki/Lee_Sm...cund_universes

Last edited by markn+; 09-21-2018 at 10:44 AM.
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Old 09-21-2018, 10:48 AM
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I think there's a basic question the OP needs to answer.

How does being in a universe-sized black hole differ from being in a universe-sized non-black hole?

If all you've done is slap on a science-y sounding term, you've done nothing.
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Old 09-21-2018, 10:52 AM
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What does "inside a black hole" even mean? There is space between the event horizon and the singularity, but we obviously aren't in that space. If we were, gravity would be so strong that light cannot travel away from the singularity.
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Old 09-21-2018, 11:17 AM
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Chronos will probably soon be here to set me straight on this, but I believe I've read somewhere there is a slight possibility that we're inside a black hole even smaller than the universe; although this would more or less require the hand of God to accomplish!
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Old 09-21-2018, 11:24 AM
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If we lived in a universe that was destined to contract into a Big Crunch at the end, then it would be true that our entire universe would be a black hole. Gravity would be so strong that nothing, not even light, could escape the inevitable contraction of everything back into a cosmic egg.

However, it doesn't seem as if we live in a universe that will have a Big Crunch, and so our entire universe probably isn't a black hole.

It's another thing to consider if the entire universe is the opposite of a black hole, a white hole. https://en.wikipedia.org/wiki/White_...ive_White_Hole.
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Old 09-21-2018, 11:26 AM
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Originally Posted by Grrr! View Post
Something I see wrong with your theory is that our universe is expanding. If we were "inside" a hole, then it should appear to us the universe is contracting.
What I am envisioning is that we, from the inside, perceive our universe expanding, but that there is a divide between the limits of that expansion and the outside universe within which it's expanding. Basically, we're inside the balloon watching it expand, but someone outside the balloon would see that expansion is limited to the capacity of the balloon.

Now, I'm going to guess that you are going to note that black holes that we observe are not expanding. I'm postulating a counterintuitive idea that they are expanding (from the perspective of within) while being simultaneously restricted in their expansion by the confines of the black hole (from the perspective of the outside).

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And we still haven't addressed: Where did the universe come from that made the star that eventually died and became a black hole that somehow created this universe?
I'm not proposing a theory of how all of existence came to be...just our little universe.

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Originally Posted by Expano Mapcase
How does being in a universe-sized black hole differ from being in a universe-sized non-black hole?

If all you've done is slap on a science-y sounding term, you've done nothing.
I'm proposing the counterintuitive notion that, while a black hole looks to be a small point from the outside, it is actually as big as a universe if you are within it.

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Originally Posted by ScR4
What does "inside a black hole" even mean? There is space between the event horizon and the singularity, but we obviously aren't in that space. If we were, gravity would be so strong that light cannot travel away from the singularity.
I'm saying that the event horizon is the outer edge of a universe, from which light (and all other things) can never escape. The singularity, defined as an infinitely small space where density and matter become infinite, is actually just the viewpoint of a universe from the outside. If you were within the singularity (as we all are, given that we are within our own universe), that "infinitely small space" is actually the "infinitely large universe" where all density and matter exist.

Again, I'm likely wrong. But it's a conceptual idea that says, simply, that there are entire universes inside black holes, which appear to us as singularities.
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Old 09-21-2018, 11:26 AM
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Originally Posted by Exapno Mapcase View Post
I think there's a basic question the OP needs to answer.

How does being in a universe-sized black hole differ from being in a universe-sized non-black hole?

If all you've done is slap on a science-y sounding term, you've done nothing.
From the observers point of view there is no difference. The composition of this universe is such that we are able to evolve and percive it. That energy/matter are somehow expelled to make another universe may be impossible to refute because there seems to be no way to get information once the material being observed crosses singularity.

This does not mean speculation about the OP idea is not interesting. I for one, having only a laypersons understanding of astrophysics, found the idea fascinating.

Since energy and matter cannot be destroyed, it makes sense that this energy and matter appears somewhere else. When I first heard of quasars I thought they were perhaps the other end of a black hole. The energy/matter has to go somewhere, so why not the other "end" of s black hole

An actual astrophysicist willing to take the time to crush our notions would be welcome ��

Last edited by ohiomstr2; 09-21-2018 at 11:28 AM.
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Old 09-21-2018, 11:27 AM
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"Inside a singularity" is a contradiction in terms, isn't it?
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Old 09-21-2018, 11:37 AM
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Originally Posted by Lemur866 View Post
If we lived in a universe that was destined to contract into a Big Crunch at the end, then it would be true that our entire universe would be a black hole. Gravity would be so strong that nothing, not even light, could escape the inevitable contraction of everything back into a cosmic egg.

However, it doesn't seem as if we live in a universe that will have a Big Crunch, and so our entire universe probably isn't a black hole. ...
Also ...

There's a simple relationship between the mass of a black hole and it's size (and therefore it's density). Years ago I'd sometimes come across a back-of-the envelope calculation as to what the density of an observable universe-sized black hole would be and it turned out to be surprisingly similar to the density of our Universe.

Then dark matter turned up. Throw in the increase in the rate of expansion of the Universe (probably no Big Crunch) and all that gets thrown out.
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Old 09-21-2018, 11:43 AM
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Originally Posted by Moriarty View Post
I have a pet theory (I might have read it somewhere) that our universe exists inside a black hole.

...

What fundamentals am I missing?
To be taken seriously, you need to address a couple of questions:
What observed phenomena does your theory predict, that aren't explained by theories that don't include a black hole that surrounds us?

What possible observations would falsify your theory?
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Old 09-21-2018, 11:50 AM
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Just as the nature of space-time inside a black hole requires everything to fall towards its center, the nature of space-time in our universe requires everything to fall forward in time. And just as it's impossible to escape from inside the event horizon of a black hole, it's impossible to escape the universe to before the Big Bang.
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Old 09-21-2018, 12:31 PM
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Very recently Roger Penrose claims evidence in a preprint for a hypothesis seemingly more far-fetched than OP's.

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Originally Posted by scr4 View Post
"Inside a singularity" is a contradiction in terms, isn't it?
I hope this question isn't directed at me! I'd have to take the side of Sam the Piano Player:
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Originally Posted by Casablanca, directed by Michael Curtiz

RICK BLAINE: If it's December 1941 at the event horizon,
what time is it near the singularity itself?

SAM the Piano Player: I dunno, Boss.
My watch stopped.
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Old 09-21-2018, 03:04 PM
Exapno Mapcase Exapno Mapcase is offline
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Quote:
Originally Posted by Moriarty View Post
I'm proposing the counterintuitive notion that, while a black hole looks to be a small point from the outside, it is actually as big as a universe if you are within it.

I'm saying that the event horizon is the outer edge of a universe, from which light (and all other things) can never escape. The singularity, defined as an infinitely small space where density and matter become infinite, is actually just the viewpoint of a universe from the outside. If you were within the singularity (as we all are, given that we are within our own universe), that "infinitely small space" is actually the "infinitely large universe" where all density and matter exist.
The singularity is a viewpoint? We're crushed inside an "infinitely small point" and that magically allows us to ... something? Infinitely small becomes infinitely large? Whoa. Heavy, man.

That black holes may seed other universes is conjecture but hugely more plausible than we're seeing the universe from inside of a singularity. Nor are the two hypotheses remotely similar or interchangeable. We're not talking about seeding other universes here. That's a different discussion.
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Old 09-21-2018, 10:48 PM
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Originally Posted by Exapno Mapcase View Post

That black holes may seed other universes is conjecture but hugely more plausible than we're seeing the universe from inside of a singularity. Nor are the two hypotheses remotely similar or interchangeable. We're not talking about seeding other universes here. That's a different discussion.
Why would our universe be special?
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Old 09-22-2018, 04:02 AM
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It's certainly an idea that's been floated every now and again, and it's not obviously wrong. There are solutions---some of them in generalizations of Einstein gravity, such as the Einstein-Cartan theory---which look like a black hole from the outside, and like a universe from the inside. Here's an article which discusses this sort of scenario---the reference to 'spin' here is not necessarily the quantum mechanical notion (although some have suggested a connection), but a property of the generalized theory of gravity that is employed, torsion, which is assumed to vanish in general relativity.
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Old 09-22-2018, 05:17 AM
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A few quick thoughts:

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I'm proposing the counterintuitive notion that, while a black hole looks to be a small point from the outside, it is actually as big as a universe if you are within it.
This puts me in mind of the idea that each sub-atomic particle could contain its own universe. An intriguing thought but ultimately a little meaningless. If it was the case is there any way we could possibly find out? What testable predictions do these hypothesis make?

It's very unlikely that your hypothesis is true simply because there are a huge number of possible (yet largely un-testable) ideas like this. It would be really weird if, say, every black hole and every electron contained its own universe. Not to mention, what would a black hole or electron look like in these child universes? Is it universes all the way down?

There is absolutely nothing wrong with speculating along these lines, it can be entertaining and spark interesting conversations or even genuine science. It's when people get overly attached to their pet theories that things go a bit pear-shaped.

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And it would seem to account for why all of the elements for life derive from stars (the ole' idea that "we are stardust").
I don't understand why you think your ideas helps with this, can you explain please? Also, nucleosynthesis is well understood, both from atomic theory and astronomical observations. The final piece of the puzzle, where some elements like gold and iodine are formed, was finally solved in 2017. We have a good (although not perfect) understanding of where all the elements come from and can trace this evolution over the history of the universe.
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Old 09-22-2018, 07:57 AM
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20 years ago or so, your idea was extremely plausible, and in fact was one of the three main competing models for the Universe. As Lemur866 says, a Big Crunch universe is, in every way that matters, the same thing as a black hole. But it wouldn't have been a black hole resulting from the collapse of a single star; it would have been a black hole resulting from the collapse of everything.

But then dark energy was discovered, which throws a real monkey wrench into everything.
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Old 09-22-2018, 10:13 AM
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Why would our universe be special?
I don't understand your question. Where did I say our universe is special?
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Old 09-23-2018, 12:48 AM
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I don't understand your question. Where did I say our universe is special?
Ok, I'll quote the whole thing this time.

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Originally Posted by Exapno Mapcase View Post
The singularity is a viewpoint? We're crushed inside an "infinitely small point" and that magically allows us to ... something? Infinitely small becomes infinitely large? Whoa. Heavy, man.

That black holes may seed other universes is conjecture but hugely more plausible than we're seeing the universe from inside of a singularity. Nor are the two hypotheses remotely similar or interchangeable. We're not talking about seeding other universes here. That's a different discussion.
How would our universe be different from the other universes that might be seeded by black holes in our universe? How would you know that it was? We're talking about crossing a singularity, after all.

Additionally how would being "seeded" by a black hole be different from being inside one?
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Old 09-23-2018, 11:08 AM
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Ok, I'll quote the whole thing this time.



How would our universe be different from the other universes that might be seeded by black holes in our universe? How would you know that it was? We're talking about crossing a singularity, after all.

Additionally how would being "seeded" by a black hole be different from being inside one?
First, it's the OP who keeps insisting that we are "inside" a black hole.

Second, any universe that is created by energy from a black hole - seeded, as I put it - is by definition not inside a black hole but its own entity, which may be unbounded according to current theory. It is not "inside" anything.

The OP has never explained whether seeding is what is being described. It seems not. The claim is that we are inside a black hole. That can't be true. "Our universe" - the one the OP specifically references - isn't, as several people have pointed out. Whether it formed from a black hole in another universe or not, we are not "inside" a black hole.

Our universe may be unique or it may be one of an infinite number of examples or anywhere in between. I don't know and made no claim about specialness.
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Old 09-24-2018, 06:15 AM
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Quote:
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The OP has never explained whether seeding is what is being described. It seems not. The claim is that we are inside a black hole. That can't be true. "Our universe" - the one the OP specifically references - isn't, as several people have pointed out. Whether it formed from a black hole in another universe or not, we are not "inside" a black hole.
Actually, at least in this thread, others are wisely saying we "probably" aren't inside a black hole. You're the only person who seems to be certain what's going on on the other side of a singularity. If you have evidence to back this up, I'd be interested in seeing it.
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Old 09-24-2018, 09:43 AM
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Actually, at least in this thread, others are wisely saying we "probably" aren't inside a black hole. You're the only person who seems to be certain what's going on on the other side of a singularity. If you have evidence to back this up, I'd be interested in seeing it.
They are not saying probably.

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Originally Posted by ftg View Post
Also ...

There's a simple relationship between the mass of a black hole and it's size (and therefore it's density). Years ago I'd sometimes come across a back-of-the envelope calculation as to what the density of an observable universe-sized black hole would be and it turned out to be surprisingly similar to the density of our Universe.

Then dark matter turned up. Throw in the increase in the rate of expansion of the Universe (probably no Big Crunch) and all that gets thrown out.
Quote:
Originally Posted by Chronos View Post
20 years ago or so, your idea was extremely plausible, and in fact was one of the three main competing models for the Universe. As Lemur866 says, a Big Crunch universe is, in every way that matters, the same thing as a black hole. But it wouldn't have been a black hole resulting from the collapse of a single star; it would have been a black hole resulting from the collapse of everything.

But then dark energy was discovered, which throws a real monkey wrench into everything.
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Old 09-24-2018, 09:50 AM
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With all this talk about peering inside a singularity, perhaps we should recall the thoughts of Sir Winston Churchill on the topic:

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Originally Posted by Winston S. Churchill
I had a feeling once about Mathematics - that I saw it all. Depth beyond depth was revealed to me - the Byss and Abyss. I saw - as one might see the transit of Venus or even the Lord Mayor's Show - a quantity passing through infinity and changing its sign from plus to minus. I saw exactly why it happened and why the tergiversation was inevitable but it was after dinner and I let it go.
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Old 09-24-2018, 07:35 PM
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They are not saying probably.
To me, those are not saying the proposal is impossible. In essence, they're saying it's not very likely given what we understand now, and the world would be a strange place if the proposed theory were true - but it could be.

And if you are certain of what you are saying, why try to discredit that part of my question? It seems easier to provide your cite, and be done with me. After all, I'm certainly not saying you're wrong. I'm saying I don't know how you can claim certainty in your belief.
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Old 09-24-2018, 09:52 PM
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To me, those are not saying the proposal is impossible. In essence, they're saying it's not very likely given what we understand now, and the world would be a strange place if the proposed theory were true - but it could be.

And if you are certain of what you are saying, why try to discredit that part of my question? It seems easier to provide your cite, and be done with me. After all, I'm certainly not saying you're wrong. I'm saying I don't know how you can claim certainty in your belief.
My understanding is that it's based on simple math. If the amount of mass-energy in the universe is 20 times what was previously thought (which is what you get when you add dark matter and dark energy to normal matter), then the black hole calculation simply doesn't work.

If you don't like it, take it up with the physicists, two of whom I've already cited because they posted in this thread.

As for your question, I didn't "discredit it," I asked you what the hell you were talking about since you put words in my mouth I never said. I've never gotten an apology for that either. I'm 100% certain that I never will. Want to prove me wrong about that?
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Old 09-24-2018, 10:58 PM
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In the real universe, black holes contain probably don't contain physical singularities that we know of. They would be light-like in a charged rotating one so that will pose a problem too.

Physics in general tends to use Perturbation Theory. You start with a simplified problem that you can solve exactly, then you move on to the next "perturbed" or solvable chunk by adding terms then...rinse and repeat as needed.

The singularity in a black hole is just the point were the mathematics of a known incomplete theory breaks down. In this case when you reach the "singularity" differential geometry fails and the entire premise of the theory are violated. The theory just cannot make any predictions at that point.

At that point there simply is no theory and the GR makes no predictions about physics there. Contrast this with the singularity at the start of time. Penrose-Hawking theories show that the start of time singularity is geometrical and physical, not topological.

Another important part here. Observers outside the event horizon will never see the singularity never form even if they could break the rules and see inside. Because from an outside observer it just won't exist in a finite amount of time. That central point source singularity is a limitation in the current math that will be reach at a finite amount of time for someone who does fall in past the event horizon.

Singularities are problems for doing the math and math is the language of physics so they are very real for those who are working on these problems.

It is not safe to assume that the singularity is a literal physical things or places or that they are even similar in the challenges they pose.
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Old 09-25-2018, 02:03 AM
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... fits with my other non-scientific science theory that the universe is teeming with life, although it is so damn big - or we are so damn small - that we have simply never encountered it. We're the proverbial ant hill in an abandoned parking lot wondering if there are other ants across the street in the grassy park - dude, ants are everywhere, but how can an ant even begin to conceive of all of those other habitats?)
Regardless whether it is inside a black hole or not, our universe is pretty damn big. I agree that the occurrence of life in the universe may be spaced out too thinly in both space and across time, that meeting others may be incredibly unlikely, but I don't see how this relates to the universe-in-a-black-hole thing. We haven't even properly explored our own solar system, which is a teeny-tiny speck in the universe we do live in - it's not as if we are even remotely close to being able to look in all the places in our own universe.
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Old 09-25-2018, 11:03 AM
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Quote:
Originally Posted by ftg View Post
Also ...

There's a simple relationship between the mass of a black hole and it's size (and therefore it's density). Years ago I'd sometimes come across a back-of-the envelope calculation as to what the density of an observable universe-sized black hole would be and it turned out to be surprisingly similar to the density of our Universe.

Then dark matter turned up. Throw in the increase in the rate of expansion of the Universe (probably no Big Crunch) and all that gets thrown out.
Trivially, the Schwarzschild radius corresponding to a universe at critical density is the Hubble radius and our Universe is very, very close to critical density (see the 'flatness problem'). The Hubble 'horizon' though is not generally speaking an event horizon, except in two cases: in a critical density radiation-only Universe without a cosmological constant/dark energy, the observable Universe is the same as the Hubble sphere; and in a dark energy-only Universe the Hubble horizon is the same as the cosmological event horizon.

Our observable Universe is several times larger than the Hubble sphere (the 'Schwarzschild radius' for a critical density universe), however, the cosmological event horizon is only slightly larger than the Hubble sphere as which is related to the fact that dark energy is currently the dominant form of energy in our Universe.

The coincidence or non-coincidence of cosmological horizons and the Schwarzschild radius though does not mean the Universe is a black hole: the Schwarzschild solution describes the vacuum around a spherically-symmetric mass and more generally, a black hole only has a precise definition when dealing with a vacuum-surrounded region, and there is no vacuum surrounding our Universe, even approximately.

Now there are more advanced ideas that see possible fundamental relationships between our Universe and black holes, but the simple idea that our Universe has some fundamental relationship to a black hole due to its density is always a non-starter.
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Old 09-25-2018, 03:15 PM
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Dark matter isn't a problem at all for the idea. Dark matter was certainly known as of when the Big Crunch model was still taken seriously; the difficulty was just that we didn't know precisely how much of it there was. And there being more of it would be support for the Big Crunch model, not refutation. The problem is dark energy. And even there, we can come up with mathematical descriptions similar to those for black holes, but which include dark energy: That's the Schwarzschild-de Sitter solution. It's just not clear whether such an object can meaningfully be described as a "black hole" any more.
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Old 09-25-2018, 08:33 PM
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Thank you for clarifying your statement, Chronos. Other than I had somehow gotten the idea in my head that the dark matter was doing the pushing expanding space (which was cleared up by reading the wiki articles on it and dark energy yesterday), that was largely how I understood it.

Last edited by scabpicker; 09-25-2018 at 08:35 PM.
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