I’ve spent something like 17 years working on a theory for which there is essentially no direct experimental support.

Relativity challenges your basic intuitions that you've built up from everyday experience. It says your experience of time is not what you think it is, that time is malleable. Your experience of space is not what you think it is; it can stretch and shrink.

I wouldn't say that The Fabric of the Cosmos is a book on cosmology. Cosmology certainly plays a big part, but the major theme is our ever-evolving understanding of space and time, and what it all means for our sense of reality.

We can certainly go further than cats, but why should it be that our brains are somehow so suited to the universe that our brains will be able to understand the deepest workings?

The bottom line is that time travel is allowed by the laws of physics.

Most scientists like to operate in the context of economy. If you don't need an explanatory principle, don't invoke it.

Far from being accidental details, the properties of nature's basic building blocks are deeply entwined with the fabric of space and time.