I used to go to Sheen High Street with my dad on a Saturday, and there was a butcher next door to the fishmonger. I hated the smell of the fishmonger, but I found the smell of the butcher's much more appealing. And I liked the big knives. I thought it looked like a decent job.

When I was about 12, I spent the summer writing four plays on my dad's old typewriter for a school play competition. And I wrote little comic bits at secondary school and at university.

Sometimes I wonder what would have happened if I hadn't become an actor. If perhaps I'd stayed on at university and become an academic.

I think having a dispassionate eye is a good way of making art. When you don't know the structures of a place, you are unencumbered.

A century ago, scientists believed there was only one obvious stomping ground for alien biology in our solar system: Mars. Because it was reminiscent of Earth, Mars was assumed to be chock-a-block with animate beings, and its putative inhabitants got a lot of column inches and screen time.

We were marooned in a frozen desert. There was not a sign of life on the horizon and a thousand signs of death... The marvel is we did not all die of cold.

I was interested in science or, at least, nature from an early age, learning the names of planets, cutting cartoons with facts about animals out of the newspaper and gluing them into a scrapbook, and, with a friend when I was five or six, trying to design a submarine.

Within the scientific community, there is healthy skepticism. And the question is, 'How do you ever get to a meaningful null result? How long and how hard do SETI scientists have to look for extraterrestrial intelligence and find nothing before they say, 'There is nothing. We are alone.'