I came across a very interesting paper entitled The Thermodynamics of Black Holes by Robert M. Wald, 2001, at the following link:
Over the past few years I have read so many books and articles about symmetry and spacetime that it is impossible to keep track of all the threads of thought that have passed through my mind. In writing the ECOS 2007 paper about spacetime, shape, symmetry and thermodynamics I wanted to include a reference to a particular idea I had read about, but was unable to find it when I went looking for it. The general notion was that if we look out into the sky, i.e. look out into spacetime, we can see the image of the structure of spacetime at the smallest scales. I found that thought very appealing and sensible.