QM Cosmology

[sapiensvsapiens]

Aren't there anyone interested in quantum cosmology and new theories set about it. It is very complicated and I'm confused. Branes and dimensions or inflation. I am a begginer and didn't get anything about the conclusion, that there was no big bang or any bang...if it was a conclusion.
Any comments ?
sapiens

[PhysBrain]

I'd be more than willing to discuss such topics. I assume by your mention of branes and dimensions that you are refering (at least in part) to string theory, and/or M-theory. I have not looked very closely at this theory yet. Most of my exposure to it was from Brian Greene's book "The Elegant Universe", and the super string theory website: http://superstringtheory.com/

As far as the theory of the big bang, there are a few different interpretations of the consequences of relativity and the observed expansion of the universe. As far as I am aware, the best working scientific theory for the origins of the universe was put forth by Steven Hawking and others. Given that the universe has been observed to be expanding, what happens if we follow this trend back in time? The theory that arose from this question became known as the big bang theory, and it goes something like this:

Everything in the known universe is thought to have formed from a very tiny and very hot ball of energy which eventually cooled into quarks and then later into subatomic particles and even later into atoms and molecules. After that, gravity took over creating stars, galaxies, and eventually planets.

Then there is the question of: Where did the tiny ball of energy come from? This gets into even more speculative territory, but a theory put forth by Alan Guth, now at MIT, proposes that it came from a very weird and highly improbable quantum fluctuation in pre-universe space. This fluctuation allowed the existence of a false vacuum which is theorized to have a highly repulsive gravitational field. This vacuum then exploded into what would become the universe that gave rise to quarks and the rest.

Well, that's pretty much a brief summary of what I know about quantum cosmology. If you have anything further to add, I'd be happy to hear it.

[bryce]

Originally posted by PhysBrain
Then there is the question of: Where did the tiny ball of energy come from? This gets into even more speculative territory, but a theory put forth by Alan Guth, now at MIT, proposes that it came from a very weird and highly improbable quantum fluctuation in pre-universe space. This fluctuation allowed the existence of a false vacuum which is theorized to have a highly repulsive gravitational field. This vacuum then exploded into what would become the universe that gave rise to quarks and the rest.


I've always liked this "Vacuum Genesis" idea, but I read about another one recently based on Membrane Theory...

Imagine our universe as one of two oscillating membranes, that can only interact gravitationally, and collide every once in a while. When a collision occurs, a new "Big Bang" is triggered in at least one of the Membrane universes. The two universes constantly exchange gravitons (or gravity in *some* form) and the mass that we *feel* gravitationally in/on the other membrane is what we feel here as "Dark Matter".

Ahhh...but where did the membranes originally come from, and what are they oscillating *through*....???

It all may be far out and perhaps even far from the truth (think I read it in Sci-Am or Astronomy, btw) but it's still kinda interesting...and who knows, it may be right on the money...I gotta catch up on my cosmology...I haven't read a book younger than 10 years old...

- bryce