General relativity is the currently favourable model of space and time, whereas quantum mechanics deals with the stuff, matter if you like, which appears in space and time.
The whole modern world works because of quantum mechanics.
Quantum theory is a really quite extraordinary subject because it does have a profoundly challenging conceptual background, yet also it’s incredibly useful.
I used to think from time to time about why did we use the mathematics that we did to talk about space and time. Basically we use real numbers. But why do we do that?
In ordinary mathematics a statement is either true or false. But apparently in Topos Theory it is the case you can have statements that are partly true and what’s even more extraordinary mathematical entities that can partially exist and partially not exist. And it suddenly hit me ‘Wow, that’s quantum theory. There’s got to be a way to use Topos Theory in quantum theory’.
One of the reasons for doing this Topos Theory wasn’t just to do quantum theory and general relativity. It was to try and find out a different way of doing theoretical physics altogether.
Original ideas are very rare actually in science. I think I had a genuinely original idea.