I suspect there could be life and intelligence out there in forms that we can't conceive. And there could, of course, be forms of intelligence beyond human capacity-beyond as much as we are beyond a chimpanzee.

In this century, not only has science changed the world faster than ever, but in new and different ways. Targeted drugs, genetic modification, artificial intelligence, perhaps even implants into our brains - may change human beings themselves.

I recall a lecture by John Glenn, the first American to go into orbit. When asked what went through his mind while he was crouched in the rocket nose-cone, awaiting blast-off, he replied, "I was thinking that the rocket has 20,000 components, and each was made by the lowest bidder."

The 'clean energy' challenge deserves a commitment akin to the Manhattan project or the Apollo moon landing.

It will not be humans who watch the sun's demise, six billion years from now. Any creatures that then exist will be as different from us as we are from bacteria or amoebae.

The important point there is that when people talk about a mean temperature rise of say two, three or four degrees that's a sort of global average which really is a signature of large scale change in climatic patterns.

I have no religious belief myself, but I don't think we should fight about it. In particular, I think that we should not rubbish moderate religious leaders like the Archbishop of Canterbury because I think we all agree that extreme fundamentalism is a threat, and we need all the allies we can muster against it.