Leg locomotion was, for decades, thought to be an incredibly difficult problem. There has been very, very painstakingly slow progress there, and robots that essentially lumbered along at one step every 15 seconds and occasionally fell over.

When I read philosophy or neuroscience papers about consciousness, I don't get the sense we're any closer to understanding it than we were 50 years ago.

Most of the AI goes into figuring which are the important pages you want. And to some extent what your query means, and what you're likely to be after based on your previous behavior and other information it collects about you.

Some people think that, inevitably, every robot that does any task is a bad thing for the human race, because it could be taking a job away. But that isn't necessarily true. You can also think of the robot as making a person more productive and enabling people to do things that are currently economically infeasible. But a person plus a robot or a fleet of robots could do things that would be really useful.

We call ourselves Homo sapiens--man the wise--because our intelligence is so important to us. For thousands of years, we have tried to understand how we think: that is, how a mere handful of matter can perceive, understand, predict, and manipulate a world far larger and more complicated than itself. The field of artificial intelligence, or AI, goes further still: it attempts not just to understand but also to build intelligent entities.

A lot of people talk about sometime around 2030, machines will be more powerful than the human brain, in terms of the raw number of computations they can do per second. But that seems completely irrelevant. We don't know how the brain is organized, how it does what it does.

It's unlikely that machines would spontaneously decide they didn't like people, or that they had goals in opposition to those of human beings.