There is an ever-widening gap between what science allows and what we should actually do. There are many doors science can open that should be kept closed, on prudential or ethical grounds.

We are 'nuclear waste' from the fuel that makes stars shine; indeed, each of us contains atoms whose provenance can be traced back to thousands of different stars spread through our Milky Way.

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.

There are lots of ideas which extend the Copernican principle one step further. We went from the solar system to the galaxy to zillions of galaxies and now to realising even that isn't all there is.

I'm not a specialist in the science but I have followed it fairly closely and it seems to me that there is among the experts a clear consensus that potential climate change is something to worry about.

If you take 10,000 people at random, 9,999 have something in common: their interests in business lie on or near the Earth's surface. The odd one out is an astronomer, and I am one of that strange breed.

Science is the one culture that's truly global - protons, proteins and Pythagoras's Theorem are the same from China to Peru. It should transcend all barriers of nationality. It should straddle all faiths, too.

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.

It is foolish to claim, as some do, that emigration into space offers a long-term escape from Earth's problems. Nowhere in our solar system offers an environment even as clement as the Antarctic or the top of Everest.

Manned spaceflight has lost its glamour - understandably so, because it hardly seems inspiring, 40 years after Apollo, for astronauts merely to circle the Earth in the space shuttle and the International Space Station.

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.

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.

The challenge of global warming should stimulate a whole raft of manifestly benign innovations - for conserving energy and generating it by 'clean' means (biofuels, innovative renewables, carbon sequestration, and nuclear fusion).

The images of Earth's delicate biosphere, contrasting with the sterile moonscape where the astronauts left their footsteps, have become iconic for environmentalists: these may indeed be the Apollo programme's most enduring legacy.

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.

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.

Not even the most secular among us can fail to be uplifted by Christianity's architectural legacy - the great cathedrals. These immense and glorious buildings were erected in an era of constricted horizons, both in time and in space.

I would support peaceful co-existence between religion and science because they concern different domains. Anyone who takes theology seriously knows that it's not a matter of using it to explain things that scientists are mystified by.

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.

The most important advances, the qualitative leaps, are the least predictable. Not even the best scientists predicted the impact of nuclear physics, and everyday consumer items such as the iPhone would have seemed magic back in the 1950s.

In the beginning there were only probabilities. The universe could only come into existence if someone observed it. It does not matter that the observers turned up several billion years later. The universe exists because we are aware of it.

A monkey is unaware that atoms exist. Likewise, our brainpower may not stretch to the deepest aspects of reality. The bedrock nature of space and time, and the structure of our entire universe, may remain 'open frontiers' beyond human grasp.

We know too little about how life began on Earth to lay confident odds. It may have involved a fluke so rare that it happened only once in the entire galaxy. On the other hand, it may have been almost inevitable, given the right environment.

One of the computer models for a four degree temperature rise would give rise to a 10 degree temperature rise in Africa. And bear in mind also that in the depth of an ice age the mean temperature drop compared to the present was five degrees.

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.

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.

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.

Campaigning against religion can be socially counter-productive. If teachers take the uncompromising line that God and Darwinism are irreconcilable, many young people raised in a faith-based culture will stick with their religion and be lost to science.

As regards my own 'philosophy,' I continue to be inspired by the music, liturgy and architectural tradition of the Anglican Church in which I was brought up. No one can fail to be uplifted by great cathedrals - such as that at Ely, near my home in Cambridge.

Maybe the search for life shouldn't restrict attention to planets like Earth. Science fiction writers have other ideas: balloon-like creatures floating in the dense atmospheres of planets such as Jupiter, swarms of intelligent insects, nano-scale robots and more.

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.

Advances in technology - hugely beneficial though they are - render us vulnerable in new ways. For instance, our interconnected world depends on elaborate networks: electric power grids, air traffic control, international finance, just-in-time delivery, and so forth.

When scientists are asked what they are working on, their response is seldom 'Finding the origin of the universe' or 'Seeking to cure cancer.' Usually, they will claim to be tackling a very specific problem - a small piece of the jigsaw that builds up the big picture.

The practical case for manned spacef light gets ever-weaker with each advance in robots and miniaturisation - indeed, as a scientist or practical man, I see little purpose in sending people into space at all. But as a human being, I'm an enthusiast for manned missions.

Stars that become supernovae start off at least eight times heavier than our sun. They're so short-lived that, even if they have planets, there is unlikely to be time for life to get started. The surface is 40,000C and, as a result, the colouring will be extremely blue.

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.

All the atoms we are made of are forged from hydrogen in stars that died and exploded before our solar system formed. So if you are romantic, you can say we are literally stardust. If you are less romantic, you can say we're the nuclear waste from fuel that makes stars shine.

In our interconnected world, novel technology could empower just one fanatic, or some weirdo with a mindset of those who now design computer viruses, to trigger some kind of disaster. Indeed, catastrophe could arise simply from technical misadventure - error rather than terror.

In the case of climate change, the threat is long-term and diffuse and requires broad international action for the benefit of people decades in the future. And in politics, the urgent always trumps the important, and that is what makes it a very difficult and challenging issue.

It would be sad if the expertise built up during the 40 years of the U.S. and Russian manned programmes were allowed to dissipate. But abandoning the shuttle, and committing to new launch vehicles and propulsion systems, is actually a prerequisite for a vibrant manned programme.

Issues relating to global health and sustainability must stay high on the agenda if we are to cope with an ageing and ever-increasing population, with growing pressure on resources, and with rising global temperatures. The risks and dangers need to be assessed and then confronted.

The scientific issues that engage people most are the truly fundamental ones: is the universe infinite? Is life just a sideshow in the cosmos? What happened before the Big Bang? Everyone is flummoxed by such questions, so there is, in a sense, no gulf between experts and the rest.

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.

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."

Space doesn't offer an escape from Earth's problems. And even with nuclear fuel, the transit time to nearby stars exceeds a human lifetime. Interstellar travel is therefore, in my view, an enterprise for post-humans, evolved from our species not via natural selection, but by design.

Indeed, our everyday world presents intellectual challenges just as daunting as those of the cosmos and the quantum, and that is where 99 per cent of scientists focus their efforts. Even the smallest insect, with its intricate structure, is far more complex than either an atom or a star.

The Blair government perhaps ranks as the best the U.K. has had for 50 years. It cannot match the scale of Attlee's reforms, but has a fine record of constitutional reform and economic competence. In my own areas - science and innovation - there have been well-judged and effective changes.

There may be organic life out there, or maybe machines created by long-dead civilizations, but any signals, even if they are difficult to decode, would tell us that the concepts of logic and physics are not limited to the hardware in human skulls, and will transform our view of the universe.

There's now, for the first time, a huge gulf between the artefacts of our everyday life and what even a single expert, let alone the average child, can comprehend. The gadgets that now pervade young people's lives, iPhones and suchlike, are baffling 'black boxes' - pure magic to most people.

The stupendous time spans of the evolutionary past are now part of common culture (though maybe not in the United States Bible Belt, nor in parts of the Islamic world). Most people are at ease with the idea that our present biosphere is the outcome of four billion years of Darwinian evolution.

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