What Do Canonical Quantum Gravity Models Tell Us About the Big Bang?

Click For Summary
SUMMARY

The discussion centers on the necessity of a quantum theory of gravity to understand the Big Bang, emphasizing mainstream approaches like String Theory and Loop Quantum Gravity (LQG). Various models, including the Pre-Big Bang model and Bounce model by Veneziano, as well as the Ekpyrotic model by Steinhardt and Turok, are highlighted for their implications on cosmology. Additional approaches such as Horava-Lifshitz gravity and Causal Dynamical Triangulation are mentioned, indicating a diverse landscape of theories that seek to explain the events of 13.8 billion years ago.

PREREQUISITES
  • Understanding of String Theory and its implications in cosmology.
  • Familiarity with Loop Quantum Gravity (LQG) concepts.
  • Knowledge of the Big Bang theory and its historical context.
  • Basic grasp of alternative gravity theories like Horava-Lifshitz gravity.
NEXT STEPS
  • Research the implications of the Pre-Big Bang model by Veneziano.
  • Explore the Bounce model and its predictions regarding the early universe.
  • Investigate the Ekpyrotic model and its alternative view on cosmic origins.
  • Study the principles of Causal Dynamical Triangulation and its relevance to quantum gravity.
USEFUL FOR

Physicists, cosmologists, and researchers interested in quantum gravity theories and their implications for the Big Bang, as well as students seeking to deepen their understanding of modern cosmological models.

skydivephil
Messages
470
Reaction score
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
 
Space news on Phys.org
Hi thanks for that , I don't have this book, if you have any comments on what the canonical QG implies for the big bang, would love to hear it.
 

Similar threads

Undergrad The standard model from loop quantum gravity via spinors octonions
  • · Replies 26 ·
Replies
26
Views
6K
Undergrad How do cosmologists view loop quantum cosmology?
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Instability of Cosmology with Quantum Corrections
  • · Replies 2 ·
Replies
2
Views
2K
Graduate Singularity structure being valid for all QFTs?
  • · Replies 6 ·
Replies
6
Views
3K
High School Book recommendations for Big Bang Model?
  • · Replies 10 ·
Replies
10
Views
4K
Graduate How Does Gravity Balance Forces Without Mass in a Pre-Big Bang Energy Scenario?
  • · Replies 10 ·
Replies
10
Views
3K
Graduate Search for literature on Quantum Gravity
  • · Replies 17 ·
Replies
17
Views
3K
Undergrad What do the authors of the paper mean here exactly by path integral?
  • · Replies 6 ·
Replies
6
Views
2K
Graduate Pre Big Bang Cosmology: Is There a Consensus?
  • · Replies 12 ·
Replies
12
Views
6K
Undergrad What Key Issues Should Cosmologists Address in the ΛCDM Model?
  • · Replies 1 ·
Replies
1
Views
3K