“I thought about the things that will truly affect humanity,” he says. “I came up with three: the internet, sustainable energy, and space travel.”

What are the major challenges we face?

Let’s go for global warming, peak oil and ubiquitous computing.

Ubiquitous computing?

Totally ubiquitous computing. One of the things our grandchildren will find quaintest about us is that we distinguish the digital from the real, the virtual from the real. In the future, that will become literally impossible