I'll read a bit more first and come back with better questions on another thread.
Coherent states aren't necessarily perturbatively connected to the vacuum right? i.e. it being nonperturbative doesn't preclude that right
The claim in string theory at least is all low energy gravitational backgrounds are indeed coherent states of graviton mode/spin 2 strings. This is discussed in Tong's note ch 7, https://arxiv.org/abs/0908.0333, and these papers from Nick Huggett, http://philsci-archive.pitt.edu/11116/, http://philsci-archive.pitt.edu/15434/I suppose this depends on your definition of coherent states. I think of them being defined in terms of a particular set of states in a Fock basis, but a generic quantum field theory is not necessarily spanned by a Fock basis
Sorry no - I had to buy the book:Do you know any place that has those in open access? I have a lot of his other writings (at least as dead trees) but not that one.
There are three people who showed essentially the same thing. Feynman in the aforementioned book, Deser did it by a bootstrap method as well as by deriving the full nonlinear GR as the unique theory from the classical limit of the quantum gravity of a spin 2 field, and Gupta as well independently.Do you know any place that has those in open access? I have a lot of his other writings (at least as dead trees) but not that one.
It has been a while, but from what I recall this equivalency certainly wasn't true at the level of rigour of mathematical physics instead of at the level of rigour of theoretical physics, where it is of course generally accepted as being true.Feynman shows it is exactly the same as GR. However I just know what I read in the book, others may know more details. A book that follows a similar approach classically is Ohanian - Gravitation:
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Its different - but equivalent - to the usual and perhaps more elegant geometric approach as is shown in the book.