In contrast the the modern belief that the universe is physical, Pythagoras (among other ancients) believed that the universe’s basic “stuff” was mathematical. After a century or so of incoherent materialism, are we finally coming back around to that idea?
Quanta magazine has a nice writeup of a new theory (not yet empirically tested, but consistent with many empirical findings) that is barnstorming theoretical physics right now: that space and time , rather than being fundamental properties of the universe, may be emergent properties of more fundamental, timeless, geometrical entities called amplituhedrons. A readable article, and an exciting idea.
There is a nice video of a lecture by the lead author, Nima Arkani-Hamed, here.
Image from here