TechTV: In "The Matrix," the laws of physics can be violated, in virtual reality. In that world, machines have taken over, and we are slaves living in a computer-generated dreamworld. Is this a possibility?

Kaku: It's possible, but unlikely. First, our machines today have the intelligence and consciousness of a cockroach. Their insect brains cannot threaten us. However, in the future, they might become as intelligent as a dog or cat. But when they become as intelligent as a monkey, many decades from now, I think they might become a threat and we should implant a chip in their brains to shut them off if they become murderous.

TechTV: In "The Matrix," the humans freed of the Matrix live in a tiny outpost called Zion deep inside the earth. Is this possible?

Kaku: Only in tiny caves, not at the centre. Contrary to Jules Verne, the earth is really solid. We know this by analysing the shock waves of earthquakes as they pass through the centre of the earth. Also, using Newton's theory of gravity, satellites can measure how solid the earth is. So Zion would have to be based in a small cave, not near the centre of the earth.

TechTV: Can virtual reality give us the Matrix?

Kaku: There are huge problems. It's extremely difficult to hook a computer into the brain. The wiring of the spinal cord is basically unknown. At best, on cats, we've been able to hook into their optic nerves, to see what a cat can see. And in blind people, we can stimulate a handful of pixels in their brain, but that's about it. The brain is still a black box. At best, scientists have, in stroke victims who are paralysed, placed an electrode in their brain and connected it to a laptop so the paralysed can move the cursor on the screen by sheer thought.

TechTV: How much computer power would be necessary to create the Matrix?

Kaku: All the computers in the world could not create the Matrix. It takes a supercomputer to simulate even simple aspects of reality, let alone the reality of billions of sleeping humans. The aliens behind the Matrix would have to be centuries ahead of our technology. (But then, if they are that advanced, they wouldn't need humans as batteries. They could just get Eveready batteries at the store instead!)...