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

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.

Science is a part of culture. Indeed, it is the only truly global culture because protons and proteins are the same all over the world, and it's the one culture we can all share.

Scientists surely have a special responsibility. It is their ideas that form the basis of new technology. They should not be indifferent to the fruits of their ideas. They should forgo experiments that are risky or unethical.

Cosmology does, I think, affect the way that we perceive humanity's role in nature. One thing we've learnt from astronomy is that the future lying ahead is more prolonged than the past. Even our sun is less than halfway through its life.

Crucial to science education is hands-on involvement: showing, not just telling; real experiments and field trips and not just "virtual reality".

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