Theory of an oscillating universe?

Question

This is a theory that is becoming more and more accepted with the scientific community. In case you aren't familiar with it, the theory states that the universe has been expanding since the big bang, and will eventually contract to produce a 'big crunch', where the universe is compressed to a singularity in about 22 billion years. The theory suggests that this action will have a rebound effect that will immediately have another big bang and this process will repeat itself, as it has been and will be for eternity. I was wondering about peoples thoughts on this?

Answer 1

The oscillatory universe hypothesis actually originated in the 1930s. It was pretty popular back in the 60s and 70s, especially among Russian astrophysicists, and Carl Sagan promoted the idea. However, it doesn't currently have a lot of support among cosmologists due to several problems.

(1) If it were to collapse, the Universe would contract into a singularity (think: black hole) and there is no known way to get a singularity to expand again. So if the Universe collapsed, current understanding says it would stay collapsed and there wouldn't be a second Big Bang, let alone a long series of them.

(2) Recent observations indicate that there is not enough mass-energy in the universe to pull everything back together again. All of the data that we currently have indicate that the Universe will not contract, it has only a fraction of the mass needed to do so. In fact, observations indicate that the expansion of the universe is accelerating, not decelerating!

(3) Finally, even if the universe could contract and then subsequently expand again, entropy would carry over from cycle to cycle. Thus, the entropy of the universe would continue to increase, it would not be reset with each new iteration. So the universe would eventually suffer heat death, proving that there cannot have been an infinite number of cycles in the past, meaning that the universe still had a beginning at some point.

In the past few years, the similarly-named Cyclic model has been proposed by some scientists working with string theory. I can't claim to understand it, but it appears to solve some of the above problems. Unfortunately, this theory's explanatory ability comes at the expense of introducing other difficulties which would then need to be addressed. Additionally, string theory itself, despite the hype, is very far from becoming established fact; it still has no good empirical evidence in its favor.

I don't suspect these sorts of cosmological issues will be resolved until physics has some type of unified theory of everything, whether that be a proven variety of string theory or something else entirely. I'll bet that you're as eager as I am for scientists to reach some firm conclusions on these issues.

See the attached two articles for further details.

Answer 2

I came across this theory years ago.
At that time the scientific community was pretty much split.
It basically comes down to the total amount of matter - is it enough to produce the gravitational forces necessary to slow down the expansion and eventually (22 billion years?) cause the matter to start contracting onto itself.
That hasn't been determined despite our modern observation technologies and numerous computer models. Some say yes - and some say no
It is an interesting theoretical physics question - but, does it have any relevance to anything that will effect us? I think not - it's like estimating our sun's remaining life span - very intriguing, but of no real significance - except, perhaps, to our great^2000 grandchildren.
I still kind of like the idea - it adds a little logic to the whole scheme of things.

Answer 3

4. steady state theory -The universe has always been and continues to be the same 3. big bang theory - The universe came from a very dense, very hot "fireball" that exploded and expanded into existence. 1. oscillating universe theory - The universe is a never-ending cycle of big bangs and big crunches 2. inflation theory - A very, very fast expansion and acceleration of the universe happened milliseconds after the big bang. If this was a homework question, I should not have answered it. If this was NOT a homework question, I realize I've been targeted and baited into answering. You are SO OBVIOUS.

Answer 4

The expansion of the universe slowed as if it was going to stop and then begin to contract towards the Big Crunch as scientists had predicted. Then, it began to expand again and pick up speed. Hubble's constant calculates that the farthest galaxies from us are now receeding from us from us, or expanding, at the speed of light. The theory now is that dark matter, or the vacuum, has overwhelmed gravity and there will be no Big Crunch. The universe will continue to disburse until it doesn't exist as we know it. The Big Rip.

http://www.msnbc.msn.com/id/3077730/