Big Bang or Cosmic Crunch?

BrianGa writes: "Yahoo news is reporting on Princeton University physicist Paul Steinhardt suggesting that the universe never began and will never end, driven forever to expand in a series of monster explosions and contract every eon or so in a cosmic crunch. This is directly contradictory to the big-bang theory. The model of the universe envisioned by Steinhardt sees the big bang as merely a turning point on an infinite road."

Comments

if this is right,

[jnana]

then perhaps Nietzsche was right after all, as I've said infinitely many times before.

Facts are...

[quantax]

I agree that we should definately continue looking for answers for this old question (the origins of the universe), but the fact of the matter is that any conclusion we come up with is more or less assumed from postulated data. This includes yesterday's post regarding the age of the universe. We can examine the universe from our position in it, but its impossible to make 100% factual judgements about certain things such as the mass of the universe, etc since there is a great deal we cannot see, and whatever is hiding behind what we can't see is included. Our data pool is limited due to our lack of ability to leave our planet or solar system in any 'real' sense. Again, we should not stop for that would be foolish, but we must remember that these findings are not fact, but theory and should be thought as such.

Re:Infinity is a very difficult concept to even..

[Transcendent]

The universe will expand and contract.. but what force is causing the expansion and contraction? Is it a natural extension of some force that we've yet to appropriately measure?

Well because there is a gravitational force between all matter within the universe, no matter how far. So eventually all matter will form into massive clumps. Even if the last 2 remaining clumps are really really really really far away (really) from eachother, there will still be a small gravitational attraction toward eachother. It will take eons for them to come together again, but it will happen... at the center of the universe.

Re:Errrr...

[adminispheroid]

Steinhardt makes much of the "singularity" in the big bang theory, but in fact nobody understands the equations of state of matter past a certain extreme of pressure and temperature. So as you try to extrapolate towards earlier and earlier times, your understanding gets vaguer. See Weinberg's "The First Three Minutes" for a discussion of this. So this part doesn't disagree with the big band theory, Steinhardt just thinks he can fill in some new parts.

He also seems to think he has an alternate solution to the flatness problem. This is the puzzle that according to gravitational theory, the curvature of space could be anything, but observationally, the curvature is zero. Seems like an odd coincidence. Guth came up with the inflation theory to explain this -- Steinhardt has another theory.

So you're right, it's not contradictory to big bang theory. But it's not really part of it either.

Re:I've always said this.

[p3d0]

The "turtles all the way down" reference is from a Brief History of Time by Stephen Hawking. You should read it. I was referring to any theory which simply begs the question. For instance, how did life evolve? Some answer that life didn't evolve on Earth, but rather came here from another planet. That simply begs the question, since it assumes that life already existed.

So, if you want to stick your head in the sand, you can say the universe began when the previous one ended. But doesn't that leave us with the question of how this infinite sequence of expanding and contracting universes came to be?

Thus, to me, the question of whether the universe is alternately expanding and contracting is mildly interesting, but not all that fundamental.