Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.

When I was a student, the laws of physics were regarded as completely off limits. The job of the scientist, we were told, is to discover the laws and apply them, not inquire into their provenance.

No planet is more earth-like than Earth itself, so if life really does pop up readily in earth-like conditions, then surely it should have arisen many times right here on our home planet? And how do we know it didn't? The truth is, nobody has looked.

Should we find a second form of life right here on our doorstep, we could be confident that life is a truly cosmic phenomenon. If so, there may well be sentient beings somewhere in the galaxy wondering, as do we, if they are not alone in the universe.

I think it enriches you as a scientist to be able to see things in an artistic perspective and as an artist to see things in a scientific perspective.

I have been spending the better part of my professional life trying to create self-driving cars. At Google, I am working with a world-class team of engineers to turn science fiction into reality.

My dad is an electrical engineer. So he was always very focused on, you know, teaching his daughters about, you know, science, math, technology. None of us actually became engineers for our careers, but I always had that exposure when I was young, and I just loved playing computer games.

Unlike physics, economists don't settle things. There seems to be plenty of room for different conclusions that are still accepted in the academy.