What does it even expand into like in terms of displacing the presumably “Nothing” that previously existed or didnt exist when the universe expanded and should have displaced or subsumed it?
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Time is a function of our universe. Before our universe, there was no time.
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If there is no time, there is infinite time.
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If there is infinite time, everything will happen.
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If everything will happen, our universe will exist.
Thus, here we are. Or, to paraphrase it in more famous words - if the universe was not as it is, we would not be here to see it.
But why are my hot pockets scalding hot on the outside and frozen in the inside!?
Because if they weren’t, you would not be here to eat them. Quite simple, really. :)
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We don’t know 🤷
One of many remaining mysteries of the universe is what expansion really means. We can measure that it is indeed expanding, but we don’t know what’s driving the expansion (other than “dark energy” which is actually only a placeholder in equations). We also have no idea about the size of the universe. Observable universe is just that - as far as we can see. But there is more beyond that we can’t see. There is no observable border to it, but we also can’t claim it’s infinite because there is a lot of proof for expansion.Why does infinity rule out expansion?
I don’t think it does. At least in mathematical sense… Something can be infinite and growing. But it’s been a long time since school so I may be off with my language.
I am not a mathematician so I am not able to well explain this concept, but there are different sizes infinities. “Infinity” is not one thing.
But there are infinite sets that contain infinite sets, so therefore there are infinities that are larger than other infinities.
It is possible that the infinite universe is expanding into another, larger, infinite space.
Or really anything is possible, we don’t know.
Numberphile has a pretty good video on different sized infinities. Newpipe is bugging out lately so I can’t dig up the video but if you’re interested you should be able to find it easily enough
I don’t think it’s even set in stone that we are expanding at all. There is another theory that the universe as we know it could be the inside of a black hole. In this scenario we could actually be shrinking instead - or rather being compressed, if that makes sense.
I think it’s pretty well established through empirical observation that the universe is expanding, based on all our current understanding of the universe. We don’t know WHY, and we don’t understand how, but it’s not really under debate at this point as a fact.
What happens inside a black hole is entirely and utterly unknown, and it’s such a crazy mind bending concept that anything we theorize is as close to informed speculation as you might get.
I’d heavily take with a grain of salt anything that replaces something we know as well as you can observe with a theory that goes something like “well maybe we’re inside a black hole.”
There is the analogy of a balloon’s surface where every point moves away from its neighbor, or a better analogy of bread expanding as it is baked, since that’s more three dimensions. The idea is that space is expanding at the atomic level at a certain rate, but it’s so small that it takes an astronomical amount of these atomic increases to be able to measure it (we can’t measure expansion at solar system scales, or even between our galaxy’s stars, as gravity drowns out the effect. But space is so large that over distances like between galaxies, the light that has traveled all that way has had to travel over this expanding so much that we can see a shift in its wavelength. And overall everything is shifting red, so either we in our section of the galaxy are the center, or it’s something that’s common in any part of our universe. One of these is far more likely.
Space is everywhere, and it’s stretching. It isn’t expanding per say, it’s that everything that is everywhere is getting further apart.
You’re thinking of space stretching like an inflated balloon, and that’s a decent analogy but it’s far more simplistic than reality. If there is some cosmic boundary it would divide everything that is and exists, and the absence of any existence. It’s a boundary which light itself could not escape, and all future points of time exist only within that boundary. All of space time would fold back in on itself.
Imagine standing at that boundary and firing an arrow, a thought experiment first described by Lucretius in Pompeii 2000 years ago. He imagined that if he fired an arrow from the edge, then clearly the universe kept going, and if it hit something, then clearly something must exist on the other side.
But the arrow can only fall back in towards the universe at some such theoretical boundary. Because all points in time exist within that boundary.
Which is very similar to a black hole. Which is why some cosmologists have suggested that maybe we live inside one.
Which is very similar to a black hole. Which is why some cosmologists have suggested that maybe we live inside one.
This would mean black holes can contain black holes, since we have also observed them inside our own universe/black hole. Which means there can be infinite universes inside each other.
😳 This toilet session turned into something else for me.
Here’s another fun fact then, any “cosmic boundary” would be surrounded on all sides by the universe, and would simultaneously exist at it’s center. Because every point in the entire observable universe is the center of the universe.
Which again sounds an awful lot like a black hole.
So maybe there is a boundary. It’s all black holes all the way down. interconnected universes all pointing to each other through black holes and Einstein-Rosen bridges all feeding off of and in to one another. The dark energy accelerating space time’s expansion coming from beyond our local event horizon in a brief moment of feeding.
I didn’t quite follow the reasoning of the first paragraph there. I would love some elaboration on that. 🙏
You are the center of the universe. A star, 2 billion light years away is also at the center of the universe.
Everything that is everywhere originated from the same infinitesimally small point that stretched out in to the universe we observe today. It’s not like a grenade going off, where you can point to a center and an edge. It’s more like proofing dough.
IF that is true, that means any “edge” to the universe must also exist at it’s center, and therefore be surrounded on all sides by the universe. It would look more like a 3 dimensional hole than a bubble we’re inside of.
Hmm. Does it make sense to say that two different points are the center? We can’t all be the center if we’re in different positions. In this case it makes more sense to me to say that there is no center. No?
If our universe exists inside a black hole, does that mean it would be potentially subject to collapse if “parent” black hole loses matter converted to energy and lost to the “parent universe” via Hawking radiation? Would this be our “big crunch”?
How do you know that isn’t already happening?
I don’t. I’m asking by applying what we know of physics in our universe, and assuming the same physics work in others (a big assumption I know). As in, I’m asking if my application is correct.
My theory is that the universe is a higher form of a sphere. If you travel along a straight line long enough, you end up in the same place you started.
On what do you base this theory of yours?
Nature is fractal/reflectve (leaf veins look like branches look like trees). Circles are a repeating motif in the universe. Planets and other bodies like stars are spherical. They travel in circular orbits. Bubbles expand uniformly, like the universe.
When you travel in circles and spheres you end up in the same place but it feels infinite/no beginning no end — like the universe. Ever expanding no beginning no end.
Maybe it would be more accurate to say that the universe is an ellipse? Since most orbits and planets and stars are not actually circles or spheres.
Still though, just because many things are elliptical doesn’t mean the universe is.
But it might be! Would be super cool.
I’ve seen it descrived as getting inflated, as in, every single point of it getting further apart.
This makes it so there’s no “nothing” to displace, there’s just more new stuff.
Not new stuff, just new space between all the stuff that’s already there.
