Preparatory knowledge to study Quantum Gravity I am an old (41-Years-old) physics graduate. I pretty much quit to "frequent physics" 10 years ago and my ability to manage physics is a bit rusty.
I was fascinated with Quantum Gravity (QG) theory and especially with the Causal Dynamical Triangulation (CDT) model developed by Loll and Ambjørn and the related approach to quantum gravity that like Loop Quantum Gravity (LQG) is background independent.
http://arxiv.org/abs/hep-th/0509010 
http://arxiv.org/abs/1105.5582 
I was wondering what would be the minimum mathematical/Physical background required to study this theory given that as graduate I learnt the following arguments on modern physics


*

*Nuclear physics

*Quantum Mechanics

*Special Relativity and Electrodynamics

*Introduction to the Structure of Matter
I know this is a quite naive question but it is never too late to learn, it says.
 A: A routine internet search for introductory material comes up with several possibilities.
If you merely wish to read about the ideas in these topics you may not need any mathematics at all. eg "String Theory and Quantum Gravity for Dummies" in the "Dummies" Series.  Also the more academic but briefer introduction "Quantum Gravity for Dummies" (http://arxiv.org/abs/1402.2757)
There are introductory texts aimed at physics graduates, such as "A First Course in Loop Quantum Gravity" by Rodolpho Gambini & Jorge Pullin.  This one is quite light on the math, and is available from Amazon (https://www.amazon.co.uk/First-Course-Loop-Quantum-Gravity/dp/0199590753).
If you need understand the mathematics, consult a postgraduate text in Mathematical Physics.  "A Course in Modern Mathematical Physics" by Peter Szekeres has good reviews.
A: If you really want to learn Quantum Gravity it is never too late to introduce yourself to General Relativity as well as Quantum Field Theory. First one is crucial for understanding Quantum Gravity because it is based on both QM and GR. 
So for more advanced studying I recommend this book http://www.cpt.univ-mrs.fr/~rovelli/book.pdf 
