- #1

ChrisVer

Gold Member

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I am looking for a pedagogical (or maybe also historical) paper that describes the attempts of quantizing gravity and the problems that appear along the lines.

It is quite interesting to hear from public talks that "when we try to canonically quantize gravity as we did EM we get problems with divergences that don't disappear/defining time/observables" and so on. But, I would like to educate myself by seeing the problems appearing with some actual (basic) calculations. I would like to see somewhere explained how things break down by applying something that is quite known. There are many such papers for example describing the procedure we follow with the EM field. So I assume that having such a discussion paper is also a "must" for someone who is interested in going through a Quantum Gravity course/research.

E.g. how we classically define the classical (to-be-quantized) "gravitational field"?

Is it the metric?

Also it would be interesting to see how the spin-2 gravitons emerged in that approach ?

Do they appear in the same way as for example photons do when we try tried to impose gauge invariance of the EM U(1) theory?

What is the gauge invariance in the case of a metric?

If the paper gives some insight on the solutions coming from either String Theory or LQG, it would be nice but not necessary.