Last Week Tonight With John Oliver/YouTube screenshot by Chris Matyszczyk/CNET

I don't want to frighten you. I'll leave it to Stephen Hawking to do that.

The famed physicist made an appearance last night on HBO's "Last Week Tonight," and had a deep and meaningful conversation with host John Oliver. Well, at least Hawking's side of the conversation was deep and meaningful.

Oliver asked him what was the one thing he most wanted people to grasp. Hawking replied: "Imaginary time."

"Imaginary time is like another direction in space," he said. "It's the one bit of my work science fiction writers haven't used."

Honestly, I though that all sci-fi was written merely by adding blood, gore, and sex to the work of scientists. So why haven't sci-fi writers built stories around imaginary time? "They don't understand it," he said.

I can't pretend to understand it either. However, it's something to do with time that runs in a different direction to the time that gnaws at us every day.

Most importantly, however, Oliver wanted to know about artificial intelligence. Like so many artificial things, it carries with it the idea that it could be noxious or even deadly.

Hawking was very reassuring: "Artificial intelligence could be a real danger in the not too distant future."

Oh, but surely not in the hands of the nice boys from Google?

Hawking, though, believes that it might be irrelevant what the nice boys from Google think. For your average robot could simply "design improvements to itself and outsmart us all."

Oliver, channeling his inner 9-year-old, asked: "But why should I not be excited about fighting a robot?"

Hawking offered a very scientific response: "You would lose."

Oliver began to worry that Hawking wasn't talking to him at all. Instead, this could be a computer spouting wisdoms. Hawking (or the robot pretending to be Hawking) replied: "You're an idiot."

But isn't this the essence of humanity? For all that we believe we know, the one thing we know best -- at least when we're honest with ourselves -- is that we're idiots. What we don't know far exceeds what we do.

Indeed, Oliver wondered whether, given that there may be many parallel universes, there might be one where he is smarter than Hawking.

"Yes," replied the physicist. "And also a universe where you're funny."