Professor Dauker, thank you so much for joining us.

What I'd like to know, or what I'd like to start off with, is why is it that reconciling

general relativity and quantum field theory is so difficult yet so important?

Thank you for having me on your podcast, Kurt, and please call me Fay.

We'll do.

It's, in my view, because the reason it's difficult to reconcile general relativity

and quantum theory, quantum field theory,

is because the concepts with which they deal are so different.

And on the one hand, quantum theory, as I understand it, it assumes that there is a

space-time background, a fixed background of space-time, whereas in general relativity, in general relativity, space-time is a dynamical object, and we simply don't know how to deal with a quantum theory where space-time itself is dynamical, where it's fully dynamical and where structures like the causal structure

are themselves dynamical in quantum theory as we know it, those things are assumed to be

fixed and we just, the conceptual struggles that we have in trying to reconcile these two theories arise in my view

because it's really a conceptual struggle.

I don't see it so much as a technical struggle at the moment.

Of course, there are technical problems within each particular approach to the problem,

but really we're struggling over what the right concepts are to work with

in this presumed deeper theory that will incorporate both generativity and quantum theory.

And because it's a struggle over concepts,

it has given rise to many different approaches. And we don't have a rich manifold of experimental data to help guide us and help us eliminate particular approaches.

Say that doesn't work because it doesn't agree with the data.

So we're using our conceptual intuitions. What feels right? What are the right ideas and physical entities,

physical concepts that are going to survive in the deep theory? What are the new ones that are

...