The heart of science is measurement.

Machines already are much smarter than us at so many things. I mean, try to multiply two 10-digit numbers with each other or, you know, sift through a thousand documents. So there's lots of things that machines are better at including in mental task than us. There's many more that they're not as good at, but the direction is pretty obvious and the progress is clear.

It's most useful to think about not jobs but tasks. And within any given job, there are lots of different tasks. If you're a radiologist maybe reading the images machines can be able to do that better, maybe making the broader diagnosis and communicating it to the patients.

Now comes the second machine age. Computers and other digital advances are doing for mental power - the ability to use our brains to understand and shape our environments-what the steam engine and its descendants did for muscle power.

For a long time, the humans are going to be better than the machines and so different parts of the job will be leveraged. In a way that's happened for centuries, and we've adapted. And it's made the people who had parts of their jobs automated more valuable and more productive to the extent that they are essential for the other components of their jobs.

Before information age, living standards basically were flat. Since then, they've been growing 2 percent a year were about 30 times richer. So technology, machines is really, you know, arguably the most important thing that's happened to humanity in terms of our living standards. You could look to the introduction of digital computers in the 1950s.

Computers get better faster than anything else ever. A child's PlayStation today is more powerful than a military supercomputer from 1996.