Spacetime... turns out to be discrete, described by a structure called spin foam. - Lee Smolin

In the theory of electric fields it is assumed that points have meaning. ...Physicists using general relativity... cannot speak of a point, except by naming some features of the field lines that will uniquely distinguish that point. ...the network of relationships evolve with time... constantly changing.

Combine general relativity and quantum theory into a single theory that can claim to be the complete theory of nature. This is called the problem of quantum gravity.

There is nothing beyond the world except what we see, no background to it except its particular history.