What happens at the edge of the universe

[Starshipcaptain16]

What would happen if you traveled faster than the rate the universe expanded to the edge of the universe?

Would you just simply exit the universe to find nothing not even physics? Would you find other universes you could somehow travel to or a multiverse? Or would you just come back to where you started?

 

[sevenperforce]

At certain times in the past, the universe expanded faster than the speed of light, and so this is not possible. 

If you could travel faster than light you would go back in time. 

If you could "jump" past the observable edge of the universe, you would reach regions of the universe that have been separated from our immediate vicinity ever since inflation began.

[Yakuzi]

As far as I was aware, we have no evidence that the universe is finite or has an "edge"... Whenever people talk about the 'edge of the universe', they generally mean the edge of the observable universe.

So in attempt to answer your question:

1. Hypothetically, you could travel beyond the edge of the current observable universe.

2. You can not reach or cross an actual edge/boundary/wall of the universe, because it doesn't exist... similar to that you can not reach or fall off the edge of the Earth.

Edited March 5, 2016 by Yakuzi

[Camacha]

20 minutes ago, Yakuzi said:

2. You can not reach or cross an actual edge/boundary/wall of the universe, because it doesn't exist... similar to that you can not reach or fall off the edge of the Earth.

Imma gonna need a source for that

[K^2]

There is very unlikely an edge to the universe. There would be all sorts of nastiness going on with fundamental fields at a boundary. We'd probably even see evidence of it in background radiation.

The universe is either infinite or is closed on itself. These are pretty much the only likely options, and neither contradicts it being a single point at Big Bang.

[Yakuzi]

48 minutes ago, Camacha said:

Imma gonna need a source for that

Wikipedia is your friend, you're looking for the "Bounded and Unbounded" section. Refer to the appropriate references for more in-depth information.*

* but yeah, we simply don't know, but an actual edge is unlikely

Edited March 6, 2016 by Yakuzi

[Camacha]

16 minutes ago, Yakuzi said:

Wikipedia is your friend, you're looking for the "Bounded and Unbounded" section. Refer to the appropriate references for more in-depth information.

Merely pointing to Wikipedia is not acceptable. You stated something as if it was a proven truth, while this is not the case. K^2, however, provided a much more reasonable answer

[Yakuzi]

20 minutes ago, Camacha said:

Merely pointing to Wikipedia is not acceptable. You stated something as if it was a proven truth, while this is not the case. K^2, however, provided a much more reasonable answer

True, I should've started with "we don't know" and added a "likely" in the second point, my bad I'm a bad boy.

 

Edit: I see why you wanted a direct reference now, I was under the impression you wanted general background info on the shape of the universe and likelihood of the existence of an "edge", hence the general referral to wikipedia.

Edited March 6, 2016 by Yakuzi

[Camacha]

1 hour ago, K^2 said:

There is very unlikely an edge to the universe. There would be all sorts of nastiness going on with fundamental fields at a boundary.

Would that be an issue? It seems the fundamental fields are formed according to what is and not vice versa. Though I am sure that it will drive physicists up the walls

[K^2]

6 hours ago, Camacha said:

Would that be an issue? It seems the fundamental fields are formed according to what is and not vice versa. Though I am sure that it will drive physicists up the walls

It's not a matter of "can't be". It's a matter of, "ought to have observable consequences." We are aware of one thing that serves as an effective boundary on space-time, and a very 'soft' one at that. It's the event horizon of a black hole. Despite not being a true boundary, but merely a coordinate singularity, it has all sorts of nasty features making it easy to spot if you're close enough. Or if it's large enough. Now, picture an entire sky covered with something even weirder. Something that's been there from beginning of the universe. I'm pretty sure we'd notice. If nothing else, in spectral composition of background radiation. It wouldn't look like thermal noise anymore.

Not that other options don't have consequences. Closed universe, for example, would render conservation of momentum less-than-absolute. To the solid state physicists, this is known as quasi-momentum. Wouldn't be equally noticeable in all possible topologies, though. And infinite universe, while most 'clean' and elegant would have ramifications that don't fully register with my poor monkey brain.

Universe is weird either way. But universe with edges would be the kind of weird that we'd probably know about by now.

[Scotius]

Can we treat event horizon of any singularity as a border of the universe?

[sevenperforce]

2 hours ago, Scotius said:

Can we treat event horizon of any singularity as a border of the universe?

Good question. 

The event horizon of a singularity is a timelike border in relativity, but not necessarily a spacelike border. And not necessarily at the levels where relativity and quantum mechanics start to bleed together. 

[WinkAllKerb'']

send someone there and wait for the answer : ) ... ralalalalala ...

[Green Baron]

From our point we can see as far out as the travel of light permits. The farthest galaxies flee from us with almost speed of light. That's our observable universe. See it that way: it's not the relative speed of the galaxies but the space itself that expands. Travelling to the edge would mean catching up with the expanding universe, which is not possible (speed limit c). To put it very easy (and i'm shure for being corrected soon :-)): a fly on an ever more rapidly expanding balloon still cannot get around because everything "flees" from it with ever greater speed.

This is the case from every point in the universe, so there might well be aereas outside of our observable universe with the same views. How big the universe really (concerning possible limits) is and whether it creates itself as it expands is probably a philosophical question ...

 

Edited March 7, 2016 by kemde

[RizzoTheRat]

If the universe is finite and there is an edge, then surely the concept of "the other side of the boundary" still doesn't exist as space and time are properties of our universe?

[K^2]

21 hours ago, Scotius said:

Can we treat event horizon of any singularity as a border of the universe?

I've addressed it somewhat in a post just above.

[Kertech]

I feel a good explanation for the "edge of the universe" is a flat landers persepctive. If you were two dimensional being only going left and right, fordward and backwards, up and down would be a mystery. Imagine if then your world was wrapped around a sphere, you would still only go l&r, f&b but you would eventully end up where you started again. (and expansion just makes this more complicated, your flat lander sphere is actually a baloon, which is being inflated faster than you could run).

[fredinno]

5 hours ago, Kertech said:

I feel a good explanation for the "edge of the universe" is a flat landers persepctive. If you were two dimensional being only going left and right, fordward and backwards, up and down would be a mystery. Imagine if then your world was wrapped around a sphere, you would still only go l&r, f&b but you would eventully end up where you started again. (and expansion just makes this more complicated, your flat lander sphere is actually a baloon, which is being inflated faster than you could run).

What if space was a sphere, but with the universe inside it? It would make more sense, the universe is 3D.

[sevenperforce]

7 minutes ago, fredinno said:

What if space was a sphere, but with the universe inside it? It would make more sense, the universe is 3D.

That would imply an edge of the universe at the sphere surface.

[Steel]

26 minutes ago, fredinno said:

It would make more sense, the universe is 3D.

Who says the universe is 3D?

[Green Baron]

16 minutes ago, fredinno said:

... the universe is 3D.

11 :-)

Whether the universe is finite or infinite is, as far as i know, subject of debate, either solution is possible. That's partly a question though ...

[sevenperforce]

17 minutes ago, kemde said:

Whether the universe is finite or infinite is, as far as i know, subject of debate, either solution is possible. That's partly a question though ...

If the universe is finite, then it is something like at least fifty times greater in volume than the observable universe, since we can detect neither local curvature nor any edge anywhere we look...

[problemecium]

Here's the scary part: Either the universe is infinite, or it's not.

If the universe is not infinite, then after warping past the event horizon at the edge of the visible universe, you'd find more galaxies for a while... and then eventually either A: loop back to where you started, or B: the universe would just stop. Personally I suspect the galaxies would come to a gradual end and empty space would just extend forever.

But if the universe IS infinite...
It's been known and thoroughly studied that the universe has a minimum possible distance, and that particles' energy states come in discrete and limited values. Thus any given finite volume of space can only contain a finite number of possible configurations of matter and energy - a huge number, but finite nonetheless. So there's only a finite number of unique cubic meters of space, for example.
So if the universe goes forever, you'd inevitably start finding the same cubic meters of space over and over again. Eventually, you'll run into an exact duplicate of yourself - and then an exact duplicate of Earth. In fact there'd be an infinite number of these. There'd even be another you busy warping through space trying to find the edge of the universe. Every possible version of you, Earth, etc. would exist - effectively, all parallel universes, and even fantasy worlds, that are not specifically prohibited by the laws of physics would exist out there in our own universe, separated from us by nothing other than vast tracts of space. This is both wonderful and horrifying - sure, there's versions just like The Lord of the Rings, for instance, but also an Earth where Hitler won World War II and exterminated all the Jews; an Earth where the Black Plague never ended and Western civilization was wiped out; an Earth that never suffered the K-T extinction and thus birds rule the world instead of mammals, so humans never came to exist... even now, if the universe is infinite there are infinite alternate copies of you, me, and everyone else suffering in horrible ways.

[insert_name]

the kraken would probably cause your ship to vibrate uncontrollably and catastrophically

[mikegarrison]

What happens if you go further and further and further and then suddenly everything goes blue and you see this: