I'm actually, for the most part, a complete agnostic politically.

Quantum mechanics brought an unexpected fuzziness into physics because of quantum uncertainty, the Heisenberg uncertainty principle.

I just think too many nice things have happened in string theory for it to be all wrong. Humans do not understand it very well, but I just don't believe there is a big cosmic conspiracy that created this incredible thing that has nothing to do with the real world.

We have one real candidate for changing the rules; this is string theory. In string theory the one-dimensional trajectory of a particle in spacetime is replaced by a two-dimensional orbit of a string. Such strings can be of any size, but under ordinary circumstances they are quite tiny,... a value determined by comparing the predictions of the theory for Newton’s constant and the fine structure constant to experimental values.

Most people who haven’t been trained in physics probably think of what physicists do as a question of incredibly complicated calculations, but that’s not really the essence of it. The essence of it is that physics is about concepts, wanting to understand the concepts, the principles by which the world works.

As far as extra dimensions are concerned, very tiny extra dimensions wouldn’t be perceived in everyday life, just as atoms aren’t: we see many atoms together but we don’t see atoms individually.

It’s indeed surprising that replacing the elementary particle with a string leads to such a big change in things. I’m tempted to say that it has to do with the fuzziness it introduces.

The theory has to be interpreted that extra dimensions beyond the ordinary four dimensions the three spatial dimensions plus time are sufficiently small that they haven’t been observed yet.

I wouldn’t have thought that a wrong theory should lead us to understand better the ordinary quantum field theories or to have new insights about the quantum states of black holes.

There was a long history of speculation that in quantum gravity, unlike Einstein’s classical theory, it might be possible for the topology of spacetime to change.