Self-Contained Models of Big Bang: Explained for Laymen

[Philm]

Hi,

Are there any self contained models of the BB that are "front-runners" as explanations for the big bang? I understand that all models have some problems with them, but which models are currently taken most seriously among working cosmologists, and are there explanations of those models for the layman?

Googling this stuff tends to lead me to explanations that are too vague, or too watered down, and usually don't contain the names of any specific models or have any kind of references. I'm hoping to get pointed in the right direction here to start reading up on this.

Thanks.

 

[Chalnoth]

What do you mean by "self-contained"?

The most commonly worked-on models for the very early universe are based upon cosmic inflation or a quantum gravity bounce.

 

[Philm]

What I mean by self-contained is that it is THE answer to our origins. In other words, it creates itself or exists necessarily and doesn't require further explanation outside of itself. Examples of this could be a multiverse with infinite regression, or an infinitesimal point that has no beginning, but then time began when it started expanding due to gravity.

 

[Chalnoth]

There aren't any leading models for that. There are some, but there's just no way to know which models are more likely.

A few of them, off the top of my head:

1. The string theory landscape. The picture here is that the universe has a huge number of possible states, and is always fluctuating. Every once in a while a fluctuation creates an inflating region which leads to a sort of pocket universe with observers in it like ourselves.
2. Sean Carroll and Jennifer Chen proposed a relatively simple model for spontaneous creation of expanding universes which doesn't depend upon any particular high-energy physics (technical paper: http://arxiv.org/abs/hep-th/0410270, popular talk on the model: ).
3. In loop quantum gravity (a currently-speculative model of quantum gravity), it looks like a collapsing universe can "bounce" to create an expanding universe like the one we observe: http://en.wikipedia.org/wiki/Big_Bounce
4. The ekpyrotic universe suggests that if two string theory branes collide, they can produce a universe like the one we observe: http://en.wikipedia.org/wiki/Big_Bounce

We currently don't have the evidence to suggest which (if any) of these ideas are correct. There are certainly other ideas that I don't recall right now (or never knew about). Maybe one day we'll have the evidence to start selecting between these ideas, but it's not easy to collect, sadly.