[T]he real world out there … must exist independently of us.

… in loop quantum gravity appeared to contradict Einstein’s special theory. … [T]hat possibility was too scary to contemplate, and after struggling with this, I dropped the whole line of research.

There is no way we can have two theories of nature covering different phenomena, as if one had nothing to do with the other. Any claim for a final theory must be a complete theory of nature. It must encompass all we know.

Don’t start with space or anything moving in space. Start with something that is purely quantum mechanical and has, instead of space, some kind of purely quantum structure.

The search for quantum gravity is a true quest.

We need a theory about what makes up space, a background-independent theory.

More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time.

[I]n both quantum theory and general relativity, we encounter predictions of physically sensible quantities becoming infinite.

SU(5) is the most elegant way imaginable of unifying quarks with leptons, and it leads to a codification of the properties of the standard model in simple terms. Even after twenty-five years I still find it stunning that SU(5) doesn’t work.