There is a very good introduction - 20 lectures of 45 minutes - to loop quantum gravity by Carlo Rovelli [1] who worked together with Lee Smolin on that topic.

There is a very good introduction - 20 lectures of 45 minutes - to loop quantum gravity by Carlo Rovelli [1] who worked together with Lee Smolin on that topic. In a nutshell loop quantum gravity is about triangulating space with tetrahedra, then representing this triangulation as a graph - one vertex per tetrahedron, one edge between every two tetrahedra sharing a face - with the edges labeled with SU(2) transformations describing the change in orientation due to spacetime curvature as one moves from one tetrahedron to a neighboring one, and of course the dynamics of this description. I hope I got this right, I am totally not a physicist. There is also a very good talk for the general public focusing on the nature of time by Rovelli [2] in case the lecture series is to long or technical. Well, I initially started writing this comment because of the quote »Leibniz argued (against Newton) that there’s no fixed backdrop to the universe, no “stuff” of space; space is just a handy way of describing relationships.«. According to Rovelli - he talks about this in the lecture series mentioned above - Newton was fully aware [3] that his notion of space and time are just abstract notions and that space and time are fundamentally relational. But due to the success of using abstract space and time in science and engineering this got somewhat forgotten and those abstract notions were and are considered much more fundamental than they are. This in lectures two (space) and ten (time) which both provide an overview about the philosophical evolution of the concepts and should be - at least the first part of the lectures - accessible without [almost] any background. [1] https://www.youtube.com/watch?v=Mp4fpwl9loQ&list=PLwLvxaPjGHxR6zr421tXXlaDGbq8S36Un https://www.youtube.com/watch?v=Mp4fpwl9loQ&list=PLwLvxaPjGH... [2] https://www.youtube.com/watch?v=-6rWqJhDv7M https://www.youtube.com/watch?v=-6rWqJhDv7M [3] I just skipped a bit through the second lecture on space and I may have somewhat overstated Newton's awareness but I will leave this as first written. It is more like he was aware that we only have access to relational space and time but we can infer from that a true abstract notion of space and time. I really recommend to just watch the lecture for a more nuanced picture, it starts out very non-technical and this very discussion.