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.

In reply, I can only plead that a discovery which seems to contradict the general tenor of previous investigations is naturally received with much hesitation.

If science has a lot to do with what works, then clearly there's much about today's social and economic setup that isn't scientific, because things aren't working very well for a majority of the world's population or the environment.

By the time a kid goes to college, if he's taking math or science, at least he knows, or you hope he knows, some basics. But if you're teaching history in college, you have a lot of damage to undo. You basically have to start over because so much of what a kid has already learned is just wrong.

It's been an enormous privilege to be the government chief scientific adviser.