LONDON — Renowned physicist Stephen Hawking may have a good grasp of the workings of the universe, but he says he can't understand Donald Trump's popularity.

Hawking tells ITV's Good Morning Britain show Tuesday that he has no explanation for the likely Republican Party president nominee's success.

"He is a demagogue who seems to appeal to the lowest common denominator," Hawking says in prerecorded comments to be broadcast when the show airs at 6 a.m. London time (0500 GMT, 1 a.m. EDT) Tuesday.

The wheelchair-bound Hawking also made a plea for British voters to choose to remain in the European Union in the June 23 referendum.

He said it is important not only for economic and security research but also to further scientific research.

Hawking says: "Gone are the days we could stand on our own, against the world. We need to be part of a larger group of nations, both for our security, and our trade."