The structure of the the paragraph you quoted and the one following it is similar to the first two long paragraphs under the "Proposed solutions to the problem of time" section of the wikipedia article.
I wrote "seems", because I found it hard to focus on an article whose second paragraph is a grotesque of General Relativity and in subsequent paragraphs brings in a not especially clearly related set of links to the author's previous articles on the recent Verlinde paper on emergent gravity and the amplituhedron, among others. :-(
There's a wikipedia article on that, of course, and it's not so bad.
https://en.wikipedia.org/wiki/Problem_of_time
The structure of the the paragraph you quoted and the one following it is similar to the first two long paragraphs under the "Proposed solutions to the problem of time" section of the wikipedia article.
There is a bit more here:
https://en.wikipedia.org/wiki/Canonical_quantum_gravity#The_...
and a technical overview in the first section of https://arxiv.org/abs/1009.2157
I wrote "seems", because I found it hard to focus on an article whose second paragraph is a grotesque of General Relativity and in subsequent paragraphs brings in a not especially clearly related set of links to the author's previous articles on the recent Verlinde paper on emergent gravity and the amplituhedron, among others. :-(