Expanding of the universe

  • Thread starter alchemist
  • Start date
50
0
the universe is expanding, ok. but what is causing this? the big bang? in that case, what causes the expansion to accelerate or decelerate? and what is beyond the boundaries of the universe?
 
837
1
Originally posted by alchemist
the universe is expanding, ok. but what is causing this? the big bang? in that case, what causes the expansion to accelerate or decelerate?
Yes, the Big Bang is responsible for the expansion. The gravitational attraction of all the matter in the universe causes the expansion to decelerate. However, it is now believed that there is some special kind of matter or radiation, called "dark energy", which has negative pressure and causes a gravitational repulsion. Right now, that repulsion appears to be winning out over the gravitational attraction of the normal matter, so there is a net acceleration.


and what is beyond the boundaries of the universe?
There is a boundary to the observable universe; beyond it is just more universe that we can't see, because light from it hasn't reached us. But the entire universe as a whole is not thought to have a boundary.
 
916
0
It's possible that this dark energy can be related with the scalar field that caused inflation?
 

theEVIL1

What is powering the exspansion? the fact that E=1.17XT (according to GR, if E is more than "1" the cosmos will collapse. My class calculated the age of the cosmos, based on this eq. at 13.989 BY. Not bad for college kids in a sophmore astrophysics class!

Just be glad it does not collapse. Then..who knows? Effect preceeds cause? what a mess.

Bill

www.wsdavis.org
 
837
1
Originally posted by meteor
It's possible that this dark energy can be related with the scalar field that caused inflation?
It's been proposed before, for instance in

http://arXiv.org/abs/astro-ph/9810509

but in general it's hard to come up with a field that correctly does double-duty as both inflaton and dark energy.
 

Related Threads for: Expanding of the universe

  • Posted
Replies
21
Views
3K
  • Posted
Replies
3
Views
2K
  • Posted
Replies
3
Views
1K
  • Posted
2
Replies
46
Views
8K
Replies
21
Views
16K
  • Posted
Replies
6
Views
2K
  • Posted
2 3
Replies
69
Views
15K
  • Posted
2 3 4
Replies
83
Views
5K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top