The universe is expanding into...?

[igualitarist]

I also hope God exists, and that He is good. Everything is better with that in mind. The idea that you lose loved ones some day, and that is it, forever, is incredibly sad. And that one day, you too shall disappear, never to again see the world, enjoy the sun, the cozy raindrops, or feel happy or sad again... incredibly tragic to think about. With God, we can hope he has a bigger purpose for us, and will bring us to a better existence.

Well, if there's 0,0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 0000000000000000000........1% of chance of God being real, then its real.

In an infinite universe, every probability, as long is bigger then 0%, will happen. And will happen all the time, Infinitely.

[Azadina]

Yes and no.

Because we also know that spacetime is part of the bubble that's expanding, not just the other stuff inside.

Also, there's galaxies that we can currently see, but will eventually NOT be able to see, because they're accelerating away from us faster than the speed of light, and eventually, their light won't be able to reach us any more.

Or we could boil all this down into "physics is fucking WEIRD when you get really big or really small".

So not only can we never see all of it, but as time goes on, we'll see less of what we can see now? Well that sucks

[Garnier Fructis]

In an infinite universe, every probability, as long is bigger then 0%, will happen. And will happen all the time, Infinitely.

This is sort of a nitpick, but events with zero probability can happen. Because zero probability is not the same as impossible. For instance, the probability that you'll find a particle in any particular location is zero, but that doesn't mean the particle is nowhere at all.

[Kelathos]

Quantum_entanglement suggests that space and distance are an illusion that can be overcome. Perhaps the expansion is not as real as you perceive it to be.

[Garnier Fructis]

Quantum_entanglement suggests that space and distance are an illusion that can be overcome. Perhaps the expansion is not as real as you perceive it to be.

That... is not what quantum entanglement says.

[igualitarist]

This is sort of a nitpick, but events with zero probability can happen. Because zero probability is not the same as impossible. For instance, the probability that you'll find a particle in any particular location is zero, but that doesn't mean the particle is nowhere at all.

Quantum mechanics just making the universe even more scarier... lol

[Garnier Fructis]

Quantum mechanics just making the universe even more scarier... lol

Nah that isn't even quantum mechanics, that's just me describing a stupid quirk of probability. Even in Newtonian mechanics, if could a particle in a box and then look inside later, the probability that it's in any one spot is zero. That's just because if you assign some small probability to each point in the box, then the fact that there are infinite points means your total probability is infinite, which is silly. So we just go 'well fuck, probability is zero then.'

[igualitarist]

So not only can we never see all of it, but as time goes on, we'll see less of what we can see now? Well that sucks

I feel bad for that random future civilization that will look at the night sky and think they are completely alone in a sea of nothingness. They will never be able to tell the history of the universe

[ArmoredDragoon]

Finite in the context of cosmology refers to some notion of distance, in which case a bounded universe that wraps in on itself would very much be finite but have no edge. This is sort of analogous to a Klein bottle.

And I'm not assuming there's a void without end. I would challenge that even if we lived in a Klein bottle-esque universe, that such a concept as the void would not make sense. So I'm not really sure what your paragraph is talking about.

To be clear, everything I've described are possibilities that cosmologists actually consider, since this is all basically a question of geometry anyway. In fact, if the curvature of the universe turns out to be positive, this is exactly what the universe will be like. As far as we can tell it's probably flat, but I'm just reiterating that I'm not presenting something logically nonsensical.

I don't think that fits well, because the Klien bottle is curved, and as far as we can tell our universe is flat.

IMO more like a tesseract. If you look at an image of a tesseract's shadow (you can't actually see what a tesseract would actually look like) you'll notice 7 cubes. There's actually an 8th cube that you can't see, but it is there nonetheless, and it actually connects the cube that is on the far left to the one that is on the far right. If you were to be placed inside of a tesseract and walk through four cubes in front of you, you'd end up right back where you started. And yet, the tesseract is flat, just like our universe.

[Deleted]

I feel bad for that random future civilization that will look at the night sky and think they are completely alone in a sea of nothingness. They will never be able to tell the history of the universe

I've always wondered what the other civilizations, if they are out there, are doing at this moment. What are their lives like? How smart are they? What is their nature?

So fascinating. The most fascinating things are the least answerable...

[Garnier Fructis]

IMO more like a tesseract. If you look at an image of a tesseract's shadow (you can't actually see a real tesseract) you'll notice 7 cubes. There's actually an 8th cube that you can't see, but it is there nonetheless, and it actually connects the cube that is on the far left to the one that is on the far right. If you were to be placed inside of a tesseract and walk through four cubes in front of you, you'd end up right back where you started. And yet, the tesseract is flat, just like our universe.

Well a tesseract is a 4 dimensional cube, so it still has a boundary (which is 3 dimensional), so not really the same concept.

[igualitarist]

Nah that isn't even quantum mechanics, that's just me describing a stupid quirk of probability. Even in Newtonian mechanics, if could a particle in a box and then look inside later, the probability that it's in any one spot is zero. That's just because if you assign some small probability to each point in the box, then the fact that there are infinite points means your total probability is infinite, which is silly. So we just go 'well fuck, probability is zero then.'

Thats interesting. But isn't this just us assigning 0% probability to a thing with a very very low chance of occurence ? Or too complicated to be calculated with accuracy at all ?

[ArmoredDragoon]

Well a tesseract is a 4 dimensional cube, so it still has a boundary (which is 3 dimensional), so not really the same concept.

If the prevailing understanding of the universe is correct, then it too has a three dimensional boundary with no central point. Much in the same, the tesseract also has no central cell, just like a cube has no central face, or a square has no central line.

[Garnier Fructis]

Thats interesting. But isn't this just us assigning 0% probability to a thing with a very very low chance of occurence ? Or too complicated to be calculated with accuracy at all ?

It's just a technicality. If you say 'what's the probability that something happens in this half of the box?' then you get a non-zero probability, because in some sense that's the only 'meaningful' question to ask.

- - - Updated - - -

If the prevailing understanding of the universe is correct, then it too has a three dimensional boundary with no central point. Much in the same, the tesseract also has no central cell, just like a cube has no central face, or a square has no central line.

The prevailing understanding says nothing about whether or not there's a boundary, since we simply don't know.

[Turalon]

It's difficult to explain.

It expands into itself at every point in space. Between every two points there is some distance and that distance is growing, taking whatever happens to be at those points with it.

Whether there's a boundary to the universe, or whether the universe's geomatry is shaped like a sphere or some other form, we'll likely never know.

This is the only post that has really been correct so far in regards to how space is expanding (at least with our current understanding of it). Space is not just expanding outward, it's also expanding into itself from every single point in space simultaneously. Even where you sit right now while reading this is actively expanding, but the reason you can't notice it is that the expansion is actually, relatively speaking, rather slow. The force of local gravity easily overpowers it and keeps things like galaxies still all held together. The reason that the universe is expanding faster than light, and still apparently getting faster is that because with every single point in space all expanding at once, additively it makes the whole of the universe when viewed as a single entity seem to be expanding faster than light.

At longer distances, like between one galaxy and another, there is enough space (which again is all expanding at every single point) that the gravity between galaxies in the long term cannot beat out the force of the massive amount of space between them expanding, and so won't be able to hold them together. This leads us to the one popular theory of the ultimate heat death of the universe and us never being able to ever reach or even see another galaxy ever again after at some far off point in the future.

As for what is at the "border" of the universe, as many others mentioned, it's all pure speculation. I could spout off some personal fun theories and ideas that I have, but I could go on all day about this sort of thing, so I'll refrain for now from making this post any longer than it already is.

[callipygoustp]

A huge ocean of LSD.

If only
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[Garnier Fructis]

We're not actually expanding in our room/planet/galaxy. It's not that we're just expanding really slowly, we're just not expanding at all because it's completely counteracted by gravity.

[PACOX]

Silence doesn't sound like anything by definition. The universe is thought to be the only place where time and space exists, thus if it expands it is good to ask what it expands into if not more space.

If space and time only exist within the universe then that means the universe is expanding into nothing. There is nothing "outside" of the universe, scientifically speaking.

[Turalon]

We're not actually expanding in our room/planet/galaxy. It's not that we're just expanding really slowly, we're just not expanding at all because it's completely counteracted by gravity.

I'm not sure what exactly you are implying here, being that phrasing is tricky with this subject often times. If you took the line about where you are sitting right now is expanding to mean that like you yourself are literally expanding and becoming larger, than yes you are correct. Gravity completely overpowers expansion at the local level, and so you, your house, planet, etc, whatever are not literally getting bigger because space is expanding.

However, at least with my understanding of it, the space that is "on top of us" , or rather that we take up space in, is indeed expanding, as is all of the fabric of space that is within our galaxy. It's just that as you said we ourselves are not in a literal sense expanding along with it. Galaxies have enough mass to hold themselves together gravitationally against the expansion that's happening right "inside" of them.

Apologies if I misunderstood what you were trying to get at here.

[Forogil]

If space and time only exist within the universe then that means the universe is expanding into nothing. There is nothing "outside" of the universe, scientifically speaking.

But the expansion we see isn't space "expanding" into the unknown - but more that space is "stretching".

An expansion would normally mean an edge going outward, but we don't know if there is an edge of the universe (could be infinite, could be "periodic" - could be odder) - and what happens there.