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A few questions about the universe and its "edge"

Leros

Lifer
Jul 11, 2004
21,867
7
81
Is the universe expanding at a rate faster than the speed of light? If not, what happens to light once it reaches the edge of the universe?

If one were to travel to the edge of the universe, at a rate faster than the speed of expansion, what would happen? Would you run into an invisible wall or what?
 

bsobel

Moderator Emeritus<br>Elite Member
Dec 9, 2001
13,346
0
0
Originally posted by: Leros
Is the universe expanding at a rate faster than the speed of light? If not, what happens to light once it reaches the edge of the universe?

If one were to travel to the edge of the universe, at a rate faster than the speed of expansion, what would happen? Would you run into an invisible wall or what?

The universe is exapanding everywhere at a constant, however given then additive effect of that constant over distance parts of the universe to an observer will appear to be moving away from each other at rates faster than light. It's like two cars going the opposite direction at 35 miles per hour. Neither is breaking the 65mph speed limit, but the speed between them is 70mph.

As for the edge, think of the universe as a balloon. You live on the outside of the balloon. The balloon is being inflated yet there is no 'edge' for you to get to.
 

Agent11

Diamond Member
Jan 22, 2006
3,535
1
0
Remember it was not too long ago we found out that the expansion of the universe is accelerating.

This is one of those things that we may think we have a good theory for.. only to have it blown by new information.

I wouldn't lose too much sleep over it.


 

Leros

Lifer
Jul 11, 2004
21,867
7
81
Originally posted by: Agent11
Remember it was not too long ago we found out that the expansion of the universe is accelerating.

This is one of those things that we may think we have a good theory for.. only to have it blown by new information.

I wouldn't lose too much sleep over it.

I figured the answer would be something along the lines of "we have no frigging clue at this point", but I just wanted to see some ideas.
 

Fox5

Diamond Member
Jan 31, 2005
5,957
7
81
Originally posted by: Agent11
Remember it was not too long ago we found out that the expansion of the universe is accelerating.

This is one of those things that we may think we have a good theory for.. only to have it blown by new information.

I wouldn't lose too much sleep over it.

Is it expanding, or is it just traveling shorter distances due to the curvature of space time? If the universe was most curved near the center, and then uncurved as it became less dense, that would allow for things to be traveling at a constant velocity yet appear to be speeding up, since more of their velocity is shifting towards one direction.
 

sao123

Lifer
May 27, 2002
12,653
205
106
Not that im a doubter or anyhting but...

If we can only see so far (IE the "Hubble Deep field") this region could be called the observed universe.

And if we assume that there is also a region called the observable universe, which would be the distance in light years equal to the amount of time passing since the big bang.

If the edge of the universe is outside this observable region... how can we possibly know what is going on outside this region?
 

Agent11

Diamond Member
Jan 22, 2006
3,535
1
0
Yeah, we need to stop killing each other and start expanding the species.. really.
All our eggs are in one fragile messed up basket.
 

Biftheunderstudy

Senior member
Aug 15, 2006
375
1
81
As far as we can tell the universe should be flat on the large scale, only around large mass concentrations is the space-time curved. There is some very detailed models that say that the universe has to be flat or it would become extrememly curved over time.

The universe is indeed accelerating which means that there is a large amount of energy in the universe which we cannot see or detect. This is the so called Dark Energy not to be confused with dark matter. Cool thing is, is that Einstein had a term in his theories which had the units of a pressure to hold the universe static--called it his greatest blunder--this constant has made a reappearance as the force pushing the universe out.