Falling out of the universe...

[gifi4]

I was talking with some friends earlier and we ended up getting into a discussion about the expansion of the universe. I posed the following question "If you were able to travel faster than the rate of expansion and you had all the time you needed, what would happen when you reached the end? Would you fall out of the universe?"

I'm sure there isn't an actual answer consider the human race hasn't made it that far yet. So I guess I'm asking for your opinions on this matter... Well, what do you think would happen?

 

[AlanJohn]

Nothing. Absolutely nothing would happen.

 

[Depravo]

If 'universe' is defined as everything that exists then logically you couldn't find yourself outside of it.

 

[Foxi4]

You can't fall out of the universe - there's nothing there. Literally nothing. Of course, provided that contemporary theories about the origins and expansion of the universe are even correct... and provided that you would somehow be capable of building a vehicle capable of going that fast without killing you and destroying itself in the process... and provided that you wouldn't hit anything on your way there... and...

Yeah, it's impossible. An interesting idea, but impossible none the less.

If 'universe' is defined as everything that exists then logically you couldn't find yourself outside of it.

Well, technically, we are all parts of the universe - we're made of matter. It's entirely possible that he'd simply be suspended in nothingness until the universe catches up with him - he's made of the same matter as everything else...

Hmm. It's a shame that this requires an impossible experiment to check.

 

[mthrnite]

To travel would imply space. No space, no travel. Space isn't expanding into space, it's space that's expanding.
I think I got that right. I'm sure somebody smarter than me will let me know if I didn't.

 

[Foxi4]

To travel would imply space. No space, no travel. Space isn't expanding into space, it's space that's expanding.
I think I got that right. I'm sure somebody smarter than me will let me know if I didn't.

But that implies that once you run out of space, you stop. Would it really be that simple? Or would the velocity of the ship simply push the "boundary of space" forward, expanding it quicker? I'm well-aware that this is beyond current human perception, but I would assume that the boundary of "space" would be visible to the naked eye.

Oh, nevermind. I just found three very plausible explainations:

First, the Universe might have what we call positive curvature like a sphere. In this case, the Universe is called "closed" and it has a finite size but without a boundary, just like a baloon. In a closed Universe, you could, in principle, fly a spaceship far enough in one direction and get back to where you started from.
The second possibility is that the Universe is flat. This kind of Universe can be imagined by cutting out a piece of a baloon material and stretching it with your hands. The surface of the material is flat and not curved. You can expand and contract it by tugging on either end. Flat Universes are infinite in extent and have no boundaries.
Finally, the Universe might be "open" or have negative curvature. Such Universes are also infinite in spatial extent and have no boundaries.
Thus whatever be the shape of the Universe, there is nothing called a boundary and hence nothing called the edge or end of the Universe.

http://curious.astro....php?number=166

 

[mthrnite]

There is no boundary.. again, a boundary would imply space outside of space. Things are simply getting farther apart from each other.

 

[Foxi4]

There is no boundary.. again, a boundary would imply space outside of space. Things are simply getting farther apart from each other.

Yeah, I just read about that out of plain curiousity.

 

[mthrnite]

I find it all to be a bit mind-numbing tbh.
My tendency as a rank layman is to think there are infinite universal bubbles of relatively concentrated matter. I think this because I've been trained to intuit things in an "as above, so below" way. In other words, big things are composed of smaller "like" things. But given that subatomic particles behave with a different set of rules than atomic particles, one would easily guess that there are a different set of laws for the super massive scale as well. So, the notion that the Universe is simply a really big atom of a larger body may not work. "As above, so below" may still apply however, just on such a grand scale that we cannot observe the pattern.

 

[Shoat]

I don't think you can be "outside the universe", even if all the practical impossibilites are put aside all you'll find is some empty space that does not have any of the big bang's background radiation, thus being truly "empty".
Or maybe space does not exist there yet. Maybe empty space, the closest thing to "nothing" was spewed outwards by the big bang alongside all matter and is expanding itself. In which case your magical spaceship that could somehow travel fast enough to get to "the edge" would probably just stop dead in it's tracks because there is nothing that it can travel through up ahead.


And if it was possible to "outrun the universe" (implying there is some sort of physical border that can be crossed with your magical spaceship, which there probably isn't) and actually be outside of it, would you continue forever at the same speed into infinite nothingness (-> in which case "universe" means "the space in which all matter exists", which is the approach that makes a bit more sense) or would you get stuck in a void where laws of physics (and, thus, motion) do not exist, thus stopping you (or, rather, your and your spaceship's scattered atoms which won't bind to each other anymore without laws of physics) right outside the border until the universe catches up (-> in which case "universe" is the space in which all matter exist and our specific laws of physics apply, and leaving it requires breaking these laws, thus allowing you to enter a room with different or even no laws of physics, which is the approach that would make for the better book/tv-show/movie)?




Note: This is just from a science fiction fan spewing some bullshit. I obviously don't have much actual knowledge about astrophysics to make assumptions from.

 

[FAST6191]

The thing is it is not quite like a balloon- if two points are getting further apart by 30 mm a year and there is another point (of equivalent distance in a straight line for the sake of example) also getting further apart by 30mm a year then the extreme two points are getting further apart by 60mm a year and then we get to expand it with another point and another.

To this end you get to a point where the relative expansion from your starting point outpaces the speed of light and thus the speed in which you can go (you carefully worded it to not have to go faster than the speed of light so I assume wormholes and FTL travel are not part of this).

This is actually related to a theory of the end of the universe where everything becomes so sparse and entropy so high everything effectively ceases to mean anything- it is called the Big Freeze if you fancy looking it up.

 

[Gahars]

You reach a toll booth. No matter how much money you've brought with you, you're always a dime short.

 

[BORTZ]

From what ive read, there are are things beyond the edges of the universe... I dont really understand it myself. Something about tons and tons of static electricity and electro magnetic waves of all kinds.

 

[pyromaniac123]

The edge of the universe is where I hide all my porn.

 

[omgpwn666]

The edge of the universe is where I hide all my porn.

Which means your porn gets farther and farther away from you by the second!!

 

[pyromaniac123]

The edge of the universe is where I hide all my porn.

Which means your porn gets farther and farther away from you by the second!!

Oh noes

 

[MelodieOctavia]

There are some theorists that believe that Pac-man had it right all along. Once you reach the boundaries of one side of the universe, you pop right back up on the other.

 

[Depravo]

From what ive read, there are are things beyond the edges of the universe... I dont really understand it myself. Something about tons and tons of static electricity and electro magnetic waves of all kinds.

Surely that's speculation of what's beyond the edges of the observable universe. If it exists it is, by definition, within the universe.

 

[yusuo]

Its hard to comprehend something never having an end, The only logical explanation for the universe is that its spherical and all existence resides inside the bubble

 

[mthrnite]

Its hard to comprehend something never having an end, The only logical explanation for the universe is that its spherical and all existence resides inside the bubble

Then the outside of the bubble wouldn't exist. If there is an outside, outside is extant, and thus is actually inside the existence bubble.