- #1
skydivephil
- 470
- 9
Most people here I think will agree that in order to understand what happened at the big bang we most likely need a quantum theory of gravity.
There do appear to be models of cosmology such as CCC or Baum/Frampton that seem to try and sidestep this requirement, but looking at quantum gravity seems to be the mainstream approach.
I would like to keep this post open to have a directory for what different approaches to quantum gravity imply about what happened at the big bang. The main approaches I have listed below with articles that are as easy to understand as I can find regarding what they predict happened 13.8 bio years ago
String/M theory:
Pre big bang model of Veneziano
www.cyberastronomo.org/LinkClick.aspx?fileticket
Bounce model also from Veneziano
http://arxiv.org/abs/hep-th/0312182
Ekpyrotic model of Steinhardt and Turok
http://wwwphy.princeton.edu/~steinh/npr/
LQG:
Big bounce
http://phys.org/news126955971.html
But according to the Wikipedia page there are may other approaches to quantum gravity other than the main two (string theory and LQG). Can anyone fill in the blanks as it were with what they predict and any useful articles? I have made a start with Horava Liftshitz gravity. But more are welcome.
Acoustic metric and other analog models of gravity
Asymptotic safety in quantum gravity
Causal Dynamical Triangulation[41]
Causal sets[42]
Group field theory[43]
Hořava–Lifshitz gravity
Matter bounce
http://arxiv.org/abs/0904.2835
MacDowell–Mansouri action
Noncommutative geometry.
Path-integral based models of quantum cosmology[44]
Regge calculus
String-nets giving rise to gapless helicity ±2 excitations with no other gapless excitations[45]
Superfluid vacuum theory a.k.a. theory of BEC vacuum
Supergravity
Twistor models[46]
Canonical quantum gravity
E8 Theory
Geometrodynamics
There do appear to be models of cosmology such as CCC or Baum/Frampton that seem to try and sidestep this requirement, but looking at quantum gravity seems to be the mainstream approach.
I would like to keep this post open to have a directory for what different approaches to quantum gravity imply about what happened at the big bang. The main approaches I have listed below with articles that are as easy to understand as I can find regarding what they predict happened 13.8 bio years ago
String/M theory:
Pre big bang model of Veneziano
www.cyberastronomo.org/LinkClick.aspx?fileticket
Bounce model also from Veneziano
http://arxiv.org/abs/hep-th/0312182
Ekpyrotic model of Steinhardt and Turok
http://wwwphy.princeton.edu/~steinh/npr/
LQG:
Big bounce
http://phys.org/news126955971.html
But according to the Wikipedia page there are may other approaches to quantum gravity other than the main two (string theory and LQG). Can anyone fill in the blanks as it were with what they predict and any useful articles? I have made a start with Horava Liftshitz gravity. But more are welcome.
Acoustic metric and other analog models of gravity
Asymptotic safety in quantum gravity
Causal Dynamical Triangulation[41]
Causal sets[42]
Group field theory[43]
Hořava–Lifshitz gravity
Matter bounce
http://arxiv.org/abs/0904.2835
MacDowell–Mansouri action
Noncommutative geometry.
Path-integral based models of quantum cosmology[44]
Regge calculus
String-nets giving rise to gapless helicity ±2 excitations with no other gapless excitations[45]
Superfluid vacuum theory a.k.a. theory of BEC vacuum
Supergravity
Twistor models[46]
Canonical quantum gravity
E8 Theory
Geometrodynamics
