Charles Darwin [is my personal favorite Fellow of the Royal Society]. I suppose as a physical scientist I ought to have chosen Newton. He would have won hands down in an IQ test, but if you ask who was the most attractive personality then Darwin is the one you'd wish to meet. Newton was solitary and reclusive, even vain and vindictive in his later years when he was president of the society.

I think all countries need to aim to cut the CO2 emissions per person, taking account of externalities like imports and exports.

Collective human actions are transforming, even ravaging, the biosphere - perhaps irreversibly - through global warming and loss of biodiversity.

It used to be controversial whether smoking caused lung cancer, it used to be controversial whether HIV caused AIDS. Now, there are a few mavericks who deny those things. In the case of climate change, I think the debate is going the same way in that there is a strong consensus that it is a serious matter.

I suspect there could be life and intelligence out there in forms we can't conceive. Just as a chimpanzee can't understand quantum theory, it could be there as aspects of reality that are beyond the capacity of our brains They could be staring us in the face and we just Don't recognise them. The problem is that we-re looking for something very much like us, assuming that they at least have something like the same mathematics and technology.

The carbon dioxide concentration in the atmosphere is measured. It's uncontroversial. It's going up. We know that has a tendency to warm the atmosphere and we should be worried about that.

In future, children won't perceive the stars as mere twinkling points of light: they'll learn that each is a 'Sun', orbited by planets fully as interesting as those in our Solar system.