From a personal perspective, I am disappointed that we have yet to really achieve a full understanding of the origins of life on Earth. What was the spark that, billions of years ago, kickstarted the process of evolution that has brought us life as we know it today? I hope that we will get some answers to that in my lifetime.

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

Devastation could arise insidiously, rather than suddenly, through unsustainable pressure on energy supplies, food, water and other natural resources. Indeed, these pressures are the prime 'threats without enemies' that confront us.

It's important that everyone realizes how much scientists still don't know.

General writing about science, even if we do it badly, helps us to see our work in perspective and broadens our vision.

The bedrock nature of space and time and the unification of cosmos and quantum are surely among science's great 'open frontiers.' These are parts of the intellectual map where we're still groping for the truth - where, in the fashion of ancient cartographers, we must still inscribe 'here be dragons.'

Indeed, the night sky is the part of our environment that's been common to all cultures throughout human history. All have gazed up at the 'vault of heaven' and interpreted it in their own way.

I've got no religious beliefs at all.

Given the scale of issues like global warming and epidemic disease, we shouldn't underestimate the importance of a can-do attitude to science rather than a can't-afford-it attitude.

The first voyagers to the stars will be creatures whose life cycle is matched to the voyage: the aeons involved in traversing the galaxy are not daunting to immortal beings. By the end of the third millennium, travel to other stars could be technically feasible. But would there be sufficient motive?

If we do find ET, we will at least have something in common with them. They may live on planet Zog and have seven tentacles, but they will be made of the same kinds of atoms as us. If they have eyes, they will gaze out on the same cosmos as we do. They will, like us, trace their origins back to a 'Big Bang' 13.8 billion years ago.

Science isn't just for scientists - it's not just a training for careers.

The lives of those such as Charles Darwin and Albert Einstein are plainly of interest in their own right, as well as for the light they shed on the way these great scientists worked. But are 'routine' scientists as fascinating as their science? Here I have my doubts.

Ever since Darwin, we've been familiar with the stupendous timespans of the evolutionary past. But most people still somehow think we humans are necessarily the culmination of the evolutionary tree. No astronomer could believe this.

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.

We do not fully understand the consequences of rising populations and increasing energy consumption on the interwoven fabric of atmosphere, water, land and life.

The Cern laboratory in Geneva was set up in 1955 to bring together European scientists who wished to pursue research into the nuclear and sub-nuclear world. Physicists then had greater clout than other scientists because the memory of their role in the Second World War was fresh in people's minds.

The atmospheric CO2 concentration is rising - mainly due to the burning of fossil fuels. It's agreed that this build-up will, in itself, induce a long-term warming trend, superimposed on all the other complicated effects that make climate fluctuate.

The scientists who attack mainstream religion, rather than striving for peaceful coexistence with it, damage science, and also weaken the fight against fundamentalism.

Perhaps future space probes will be plastered in commercial logos, just as Formula One cars are now. Perhaps Robot Wars in space will be a lucrative spectator sport. If humans venture back to the moon, and even beyond, they may carry commercial insignia rather than national flags.

The extreme sophistication of modern technology - wonderful though its benefits are - is, ironically, an impediment to engaging young people with basics: with learning how things work.

If we ever established contact with intelligent life on another world, there would be barriers to communication. First, they would be many light years away, so signals would take many years to reach them: there would be no scope for quick repartee. There might be an IQ gap.

Over most of history, threats have come from nature - disease, earthquakes, floods, and so forth. But the worst now come from us. We've entered a geological era called the anthropocene. This started, perhaps, with the invention of thermonuclear weapons.

The Swedish engineer who invented the zip fastener made a greater intellectual leap than many scientists do in a lifetime.