Physicist Brian Cox has weighed in one of astronomy's most curious questions: Given the high probability of extraterrestrial life existing in the endlessly massive universe, why haven't we seen any clear evidence of it?

This question was first put forward by Italian physicist Enrico Fermi in the 1950s, in what’s now known as the Fermi paradox. He argued there's a contradiction between the high probability of alien life existing and the total lack of hard evidence that intelligent life has ever evolved outside of Earth.

“Where is everybody?” he famously asked.

Well, Professor Cox thinks he might have the answer. But it isn’t too cheery.

According to the Sunday Times, Cox said: “One solution to the Fermi paradox is that it is not possible to run a world that has the power to destroy itself and that needs global collaborative solutions to prevent that.”

Yup, essentially there's a chance aliens wipe themselves out via political turmoil before they ever become advanced enough to launch an interstellar exploration.

He went on to warn: “It may be that the growth of science and engineering inevitably outstrips the development of political expertise, leading to disaster. We could be approaching that position.”

Gulp.