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>"space itself is expanding (into what? nobody knows)" I have a terrifying theory on this (granted, the Earth will be long gone). What if the universe is not a

>"space itself is expanding (into what? nobody knows)" I have a terrifying theory on this (granted, the Earth will be long gone). What if the universe is not actually expanding in the sense that it is being propelled by an initial explosion, but instead falling towards a much greater mass - the end of time so to speak, where all mass ends. Considering that gravity is a "weak force", the scale of such a mass makes me uncomfortable to think about. Perhaps what we observe as the fabric of space-time itself "stretching" is actually a similar process to what happens to matter as it enters a black hole?

YorickPeterse 6y ago
Isn't this basically what the Big Rip hypothesis is about?
bena 6y ago
It's possible. The issue is that the we really don't have any information beyond what we have. We have an idea of the big bang and the expansion of the universe. We have knowledge of certain factors etc. But really, we're not really equipped to handle the scale of the cosmos.
DeRock 6y ago
If you want to delve further into this idea, check out http://www.flatuniversesociety.com http://www.flatuniversesociety.com
meowface 6y ago
From my layman's perspective, I think this is plausible, and many physicists seem to agree it's plausible. Maybe another plausible explanation could be the reverse: maybe before the Big Bang, our/the universe was in the state you describe, and the Big Bang is our perception of it "snapping back" and exploding violently outward (aka a white hole). Carlo Rovelli and others propose that black holes actually only appear as they do to us due to the extreme time dilation, and similar to how a photon's "perspective" is that it's experiencing all of time at once, a black hole's perspective is that it's basically a massive explosion that occurs at essentially the same moment it forms. So under this hypothesis, a black hole never reaches a true singularity, but as close to a singularity as physically possible, and then it almost instantaneously bounces back like a taut rubber band that's stretched back as far as it'll go. From our perspective on the outside, it's an intense explosion occurring in very slow motion, and from the perspective on the inside, it's an intense explosion happening all at once. Rovelli posits a Planck star, not a singularity, exists past the black hole's event horizon, and the Planck star is the state of maximal compression between the black hole and white hole phases. And somewhat related to this, if I understand the theories correctly, our universe might be a supermassive white hole, and we might hold the perspective of being inside of a super(super)massive black hole that's turned into a white hole and is exploding and jettisoning everything inside of it. Or some stage after that. The ultra-compressed energy before the Big Bang would be an (extremely massive and dense) Planck star. I have no idea how likely the Planck star theory or white hole universe theory might be, but my blind speculation is that if it's true, maybe dark energy is whatever's fundamentally responsible for gravity/curvature causing our white hole explosion to bend some outer medium - the hypothetical potential medium which our black hole/universe originally formed in - and interact with other extreme contractions and explosions also happening in that medium, in complex and multivariate ways. Maybe a white hole being pushed into or prodded or yanked by many other black holes and white holes from different directions and angles could be perceived from the inside as accelerating expansion of space at certain scales. Maybe this is happening recursively, even; maybe that outer medium is itself within another even greater medium, which also is within another greater medium, etc. Maybe the nesting depth is small, or near-infinite, or infinite. Or maybe there is no outer medium to our universe, in which case that whole idea's shot. And I'm not sure if this could be related, but Rovelli suggests the hypothetical Planck star cycle of black hole to white hole applied to primordial black holes that formed in our early universe could explain dark matter, so even without the outer medium idea there could be something here that helps us understand our large-scale observations. Maybe there could be some relation to the "dark fluid" and negative energy idea, too: https://en.m.wikipedia.org/wiki/Dark_fluid https://en.m.wikipedia.org/wiki/Dark_fluid I have absolutely no clue if your or my speculation is reasonable or not (there's currently zero evidence of any sort of outer medium, as far as I know), but the general concept of our universe being the result of a black and/or white hole does definitely seem to interest a lot of physicists.
- jquery 6y ago
  > Carlo Rovelli and others propose that black holes actually only appear as they do to us due to the extreme time dilation, and similar to how a photon's "perspective" is that it's experiencing all of time at once, a black hole's perspective is that it's basically a massive explosion that occurs at essentially the same moment it forms. So under this hypothesis, a black hole never reaches a true singularity, but as close to a singularity as physically possible, and then it almost instantaneously bounces back like a taut rubber band that's stretched back as far as it'll go. From our perspective on the outside, it's an intense explosion occurring in very slow motion, and from the perspective on the inside, it's an intense explosion happening all at once. I’ve been yelling like a crank for a while that a black hole is actually a massive explosion we see in (ultra) slow motion, so it’s really cool to hear I’m not alone, and that other people call it a “planck star”. I haven’t heard anyone connect that to the big bang being a white hole, but it does make a lot of sense, even if we currently have no direct observable evidence or even any theoretical predictions. Thanks for sharing, now I can follow along the research.
  - meowface 6y ago
    Don't know why you're being downvoted. It's definitely not too crazy of an idea, given what's been known since general relativity was confirmed and the discovery that black holes do indeed exist. I haven't looked into it, but I wouldn't be surprised if many other people have proposed it in the past. I haven't heard or thought of it before, but when I first read it it definitely made a lot of sense, intuitively. Maybe the downvotes (which seem to no longer outweigh the upvotes?) are because you said "is actually" rather than "might actually be". Humility and uncertainty is crucial in science. Even for a field that's much more testable, and even for a leading scientist in a field, let alone some random speculator on the internet. It's fun to think and talk about these things, but especially as total amateurs, we should never claim anything with even a little bit of confidence. My own speculative stuff I posted above is probably all dead wrong and hopelessly confused; I'm just throwing it out there as stuff that's popped into my head. And Rovelli may be wrong, too, though he's a highly-respected theoretical physicist and has published several papers about it. And even if the Planck star and black hole/white hole theory is true, it may not necessarily mean it has anything to do with how our universe started; that's just additional unsubstantiated speculation by me and some other people, and not anything Rovelli has claimed, though his theory seems to have increased discussion about that topic. Here're some resources: https://phys.org/news/2014-02-astrophysicists-duo-planck-star-core.html https://phys.org/news/2014-02-astrophysicists-duo-planck-sta... https://en.wikipedia.org/wiki/Planck_star https://en.wikipedia.org/wiki/Planck_star https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassive_White_Hole https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassi...
Swizec 6y ago
My high school physics professor had a great take on this: The universe is defined as “everything”. If we ever find anything outside the universe, we’ll call that the universe too.
- whatshisface 6y ago
  That doesn't really answer the question, what the parent is really asking about is whether we are living on the surface of a manifold that's due for some kind of a collision with something else.
- GlennS 6y ago
  The atom used to be defined as the smallest indivisible thing, but we didn't rename it when we learned that you could split them into smaller things.
throwaway568 6y ago
Interesting, this adds to a thought I had a couple of weeks ago. We can see the past, but we can’t go there, like an observer inside event horizon looking out, they can see light coming in, but can’t leave. We can’t see the future, but when we are going there, like an observer falling into the event horizon. They can’t see what’s inside, but they can fall inside. As we experience time, it’s like we are falling into a black hole made of time.

YorickPeterse 6y ago

Isn't this basically what the Big Rip hypothesis is about?

bena 6y ago

It's possible. The issue is that the we really don't have any information beyond what we have. We have an idea of the big bang and the expansion of the universe. We have knowledge of certain factors etc. But really, we're not really equipped to handle the scale of the cosmos.

DeRock 6y ago

If you want to delve further into this idea, check out http://www.flatuniversesociety.com http://www.flatuniversesociety.com

meowface 6y ago

From my layman's perspective, I think this is plausible, and many physicists seem to agree it's plausible. Maybe another plausible explanation could be the reverse: maybe before the Big Bang, our/the universe was in the state you describe, and the Big Bang is our perception of it "snapping back" and exploding violently outward (aka a white hole). Carlo Rovelli and others propose that black holes actually only appear as they do to us due to the extreme time dilation, and similar to how a photon's "perspective" is that it's experiencing all of time at once, a black hole's perspective is that it's basically a massive explosion that occurs at essentially the same moment it forms. So under this hypothesis, a black hole never reaches a true singularity, but as close to a singularity as physically possible, and then it almost instantaneously bounces back like a taut rubber band that's stretched back as far as it'll go. From our perspective on the outside, it's an intense explosion occurring in very slow motion, and from the perspective on the inside, it's an intense explosion happening all at once. Rovelli posits a Planck star, not a singularity, exists past the black hole's event horizon, and the Planck star is the state of maximal compression between the black hole and white hole phases. And somewhat related to this, if I understand the theories correctly, our universe might be a supermassive white hole, and we might hold the perspective of being inside of a super(super)massive black hole that's turned into a white hole and is exploding and jettisoning everything inside of it. Or some stage after that. The ultra-compressed energy before the Big Bang would be an (extremely massive and dense) Planck star. I have no idea how likely the Planck star theory or white hole universe theory might be, but my blind speculation is that if it's true, maybe dark energy is whatever's fundamentally responsible for gravity/curvature causing our white hole explosion to bend some outer medium - the hypothetical potential medium which our black hole/universe originally formed in - and interact with other extreme contractions and explosions also happening in that medium, in complex and multivariate ways. Maybe a white hole being pushed into or prodded or yanked by many other black holes and white holes from different directions and angles could be perceived from the inside as accelerating expansion of space at certain scales. Maybe this is happening recursively, even; maybe that outer medium is itself within another even greater medium, which also is within another greater medium, etc. Maybe the nesting depth is small, or near-infinite, or infinite. Or maybe there is no outer medium to our universe, in which case that whole idea's shot. And I'm not sure if this could be related, but Rovelli suggests the hypothetical Planck star cycle of black hole to white hole applied to primordial black holes that formed in our early universe could explain dark matter, so even without the outer medium idea there could be something here that helps us understand our large-scale observations. Maybe there could be some relation to the "dark fluid" and negative energy idea, too: https://en.m.wikipedia.org/wiki/Dark_fluid https://en.m.wikipedia.org/wiki/Dark_fluid I have absolutely no clue if your or my speculation is reasonable or not (there's currently zero evidence of any sort of outer medium, as far as I know), but the general concept of our universe being the result of a black and/or white hole does definitely seem to interest a lot of physicists.

jquery 6y ago
> Carlo Rovelli and others propose that black holes actually only appear as they do to us due to the extreme time dilation, and similar to how a photon's "perspective" is that it's experiencing all of time at once, a black hole's perspective is that it's basically a massive explosion that occurs at essentially the same moment it forms. So under this hypothesis, a black hole never reaches a true singularity, but as close to a singularity as physically possible, and then it almost instantaneously bounces back like a taut rubber band that's stretched back as far as it'll go. From our perspective on the outside, it's an intense explosion occurring in very slow motion, and from the perspective on the inside, it's an intense explosion happening all at once. I’ve been yelling like a crank for a while that a black hole is actually a massive explosion we see in (ultra) slow motion, so it’s really cool to hear I’m not alone, and that other people call it a “planck star”. I haven’t heard anyone connect that to the big bang being a white hole, but it does make a lot of sense, even if we currently have no direct observable evidence or even any theoretical predictions. Thanks for sharing, now I can follow along the research.
- meowface 6y ago
  Don't know why you're being downvoted. It's definitely not too crazy of an idea, given what's been known since general relativity was confirmed and the discovery that black holes do indeed exist. I haven't looked into it, but I wouldn't be surprised if many other people have proposed it in the past. I haven't heard or thought of it before, but when I first read it it definitely made a lot of sense, intuitively. Maybe the downvotes (which seem to no longer outweigh the upvotes?) are because you said "is actually" rather than "might actually be". Humility and uncertainty is crucial in science. Even for a field that's much more testable, and even for a leading scientist in a field, let alone some random speculator on the internet. It's fun to think and talk about these things, but especially as total amateurs, we should never claim anything with even a little bit of confidence. My own speculative stuff I posted above is probably all dead wrong and hopelessly confused; I'm just throwing it out there as stuff that's popped into my head. And Rovelli may be wrong, too, though he's a highly-respected theoretical physicist and has published several papers about it. And even if the Planck star and black hole/white hole theory is true, it may not necessarily mean it has anything to do with how our universe started; that's just additional unsubstantiated speculation by me and some other people, and not anything Rovelli has claimed, though his theory seems to have increased discussion about that topic. Here're some resources: https://phys.org/news/2014-02-astrophysicists-duo-planck-star-core.html https://phys.org/news/2014-02-astrophysicists-duo-planck-sta... https://en.wikipedia.org/wiki/Planck_star https://en.wikipedia.org/wiki/Planck_star https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassive_White_Hole https://en.wikipedia.org/wiki/White_hole#Big_Bang/Supermassi...

Swizec 6y ago

My high school physics professor had a great take on this: The universe is defined as “everything”. If we ever find anything outside the universe, we’ll call that the universe too.

whatshisface 6y ago
That doesn't really answer the question, what the parent is really asking about is whether we are living on the surface of a manifold that's due for some kind of a collision with something else.
GlennS 6y ago
The atom used to be defined as the smallest indivisible thing, but we didn't rename it when we learned that you could split them into smaller things.

throwaway568 6y ago

Interesting, this adds to a thought I had a couple of weeks ago. We can see the past, but we can’t go there, like an observer inside event horizon looking out, they can see light coming in, but can’t leave. We can’t see the future, but when we are going there, like an observer falling into the event horizon. They can’t see what’s inside, but they can fall inside. As we experience time, it’s like we are falling into a black hole made of time.