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Our Universe appears to be expanding and cooling, having originated some 13.8 billion years ago in a hot Big Bang. However, it's plausible that what we see from inside our Universe is simply the result of being inside a black hole that formed from some parent Universe. If the black holes that form in our cosmos give birth to baby Universes, perhaps we arose from the formation of a black hole ourselves.
I've seen this pop up a few times, but there are a couple big issues that pop up right out the gate.
Space is constantly expanding with no center. If we're in a back hole, we and everything else in here are cruising toward the singularity. And if we're in a black hole, we're already passed the event horizon, the point at which gravity is so strong that even light can't escape; and as we progress toward the singularity, that force becomes exponentially stronger... so light from one point inside the black hole would have very limited potential to cross paths with another point... so how is it light from stars is actually making it to us / for the few stars we're actually in the line of fire for it's light - if that's even possible inside the event horizon - shouldn't the night sky only have a narrow region of visible stars; and shouldn't they appear distorted as s all hell?
It seems like you are making the assumption that time and the laws of physics follow the same rules inside the singularity. If we ourselves are inside a singularity, the net result was enough matter to create our known universe... but maybe in the next layer down matter behaves differently and stars can be produced on a smaller scale. Or maybe the matter is heading towards its own scale of big-bang. And what if time contracts to the point that the life of the black hole, and its relative size, corresponds to the life of that universe and its expansion?
A story which comes to mind and presents an interesting theory that could apply here can be found in He Who Shrank.
We'd be somewhere between the event horizon and the singularity - once we've made it to the singularity we'd just be crushed into it to join the infinitely dense speck of matter.
Between the event horizon and singularity we can still exist as a unique object/entity, we just can't move any matter/energy from the inside out.
But once we reach the singularity, we just become more mass in the singularity. No more me, or you, or Earth, etc: just singularity.
The time it takes to move from event horizon to singularity would scale with the size of the black hole, so I guess if the singularity had enough mass to generate an event horizon the size of what we understand to be the universe, then yeah the trillions of years it would take for things like Earth to form, life to develop, etc could all happen as we move closer to the singularity, but we run into the snags like the ones I mentioned in my first post - the observable universe would all be on a crash course toward the same point, and not uniformly moving away from everything as space expands; and the further out we look into space, the more distorted it would become: distant galaxies wouldn't appear as neat discs, but as stretched lines. We could even use that distortion to infer the approximate location of the singularity and gauge how much time is left before we're smashed into it.
But you're still judging all of this based on our current laws of physics, or that anyone even knows for certain what is occurring within a black hole. Also remember that time loses all conventional meaning once you pass the event horizon. Now compare that to what we think we know of our own big-bang... that we believe all matter started as a singularity, and that in the initial expansion both time and the very laws of physics were quite muddy and took a bit to settle into what we know today. Within the black hole we don't even know if the concept of matter still has the same meaning -- what appears as a known value of X suns to us could resolve to a whole universe if the physics change.
I'm curious why you think the matter coming it to a black hole would be observed are rushing towards the singularity? We've already seen just how insanely that much gravity distorts the perceptions around the outside of a black hole, so why wouldn't the same be true on the inside? Our own universe has a finite amount of matter, and yet the space it is 'contained' in wraps around on itself so there is no center. The boundary of a black hole could potentially create the same result -- a threshold that we could never cross, but also a wrapping of the space within back onto itself. Also consider the unknown nature of time, what if all the matter that will ever be consumed by the black hole feeds into that singularity while simultaneously exploding into the life of a new universe? In a place where time doesn't exist, all of time would happen simultaneously, so from another viewpoint the billions of years (not trillions) that comprise the history of the life and death of our universe could happen all at once. We know that as we look back towards the time of our own singularity the math surrounding time and space break down to a point where they no longer have any meaning. The same is true for what happens inside a black hole, it all breaks down and become meaningless under our current math. Until we know more about what is happening, or find some way to peer back before the big bang, you really can't discount the idea that what happens inside a black hole could be similar to the creation of a new universe. What appears to us as stringification could be the result of the math showing us the entire history of a moving object instead of a single point in time. Hell we don't even know if time works the same way, maybe once you cross the event horizon time starts moving backwards and what we see as everything moving towards a singularity appears in there as a universe expanding away from it.
Yes all of this sounds like fantastical sci-fi stuff. Then again, what we know about the birth of our universe and how space and time are warped within a black hole also sounds like fantastical sci-fi stuff, and until we have a better grasp on the nature of all of it, there's nothing yet that proves or disproves if a whole universe could exist inside a black hole.
I mean, yes I'm assuming they follow the laws of physics. To my knowledge everything about them that we actually can observe does actually follow the laws of physics (including things like time dilation), and we can use what we do know to form a pretty solid hypothesis about what we don't.
I mean, I could argue that they're actually c'thulu eggs, and you can't prove me wrong because we can't look inside! ...but there's also no evidence to support that. Drawing conclusions about reality based on science fiction is silly. We ofc don't know everything about the universe, but we should stick with what real evidence actually supports.
I find it unlikely that the laws of physics apply within a singularity, the place in which there exists more matter than is possible to exist in a single point. Plus, information/matter is effectively shredded and turned into particles by the black hole. There is no way for scientists to empirically prove what actually happens after entering the event horizon, so holding out for evidence is folly. Perhaps you could be more theoretical with your theoretical physics.
Yeah I agree that we shouldn't try to contradict the evidence we have without a good hypothesis to back it up, I just feel like we're still at a stage where the mathematics give us an idea of what might be possible, but that is seriously constrained by our limited understanding of what happens at these grand scales. Without letting your mind wander to the possibilities of what could be, we would never take the time to look beyond what we know. I'm just trying to say that our knowledge of the subject is still greatly limited, and this idea can't be ruled out completely until we know more. In the meantime, what if someone did seriously explore the notion? Perhaps they'll find proof that shows it can't be possible, but perhaps they might also stumble upon a idea even more fantastic.
That's what I'm saying though - the hypothesis that we exist in a black hole does contradict the evidence currently available. Or at least I think it does - I opened the contractions initially as a question because this isn't my area of expertise. I've had a few relevant classes, and have a casual interest in the topic, so I think I have a pretty solid foundation at least; but ultimately I'm just a medic, so I was kinda hoping someone with a more dedicated background would chime in.
There's a LOT of BS surrounding the topic of black holes - and understandably so. They're intriguing as hell, so it's no wonder that they're so often the object of artistic freedom. But all's fine and well to proclaim that they're some kind of portal, or mini universe, or cleverly disguised alien spacecraft, or even a sentient creature... in the context of science fiction. But to say any of those about black holes IRL should come with supporting evidence, especially if some aspect of the proposal clashes with our current interpretation of what we can either directly observe or indirectly postulate.