I used to say that if you gave me a trillion dollars to build a sentient or conscious machine I would give it back. I could not honestly say I knew how it works.

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.

Its really important to understand the difference between sentience and consciousness, which are important for human beings.

To my knowledge nobody - no one who is publishing papers in the main field of AI - is even working on consciousness. I think there are some neuroscientists who are trying to understand it, but I'm not aware that they've made any progress.

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.

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.