ME and Ophelia

THREATS TO TOMORROW'S WORLD
A DIY guide to saving Planet Earth

A friend has just emailed me an article from the Telegraph 29/11/2005 with a note saying there is a wonderful webcast of Lord May talking about the same things on his last day as President of the Royal Society, yesterday.

The article, entitled A DIY guide to saving Planet Earth, is copied here in full for future reference:

Human survival depends on problem fixing not avoidance - in particular learning how to cool down our planet, says David Deutsch:

Let's start with a couple of ideas that everyone knows. The first - dramatically named Spaceship Earth - is that our planet is uniquely suited to us and our survival. The universe outside is implacably hostile; if we mess up our spaceship, we have nowhere else to go.

The second is that, despite our traditional self-image, human beings are not the hub of existence: as Stephen Hawking famously put it, we're just a chemical scum on the surface of a typical planet in orbit around a typical star on the outskirts of a typical galaxy.

Everyone knows these things, yet they are both false. In fact, if you were looking for a pair of truths so important that it's worth carving them on blocks of stone and reciting them every morning before breakfast, you could do a lot worse than to carve denials of those two ideas.

Are we at a typical place? Most places in the universe are not on a planet, or even in a galaxy. Travel right outside the galaxy - say, 100,000 light years - and you still haven't reached a typical place. You will have to go about 1,000 times as far, into deep, intergalactic space, so remote that if the nearest star were to explode as a supernova, it would be too faint to see.

It's also very cold, less than three degrees above absolute zero. And it's empty: less than one millionth the density of the highest vacuum that scientists can currently attain.

That is how unlike Earth a typical location is. Yet the two are similar in one remarkable way.

Take a telescope and gaze even further out than where we've just been, at a "quasar". That was originally short for "quasi-stellar object", meaning "it looks like a star". But we now know what it really is. Billions of years ago, and billions of light years away, the centre of some galaxy collapsed towards a super-massive black hole.

Intense magnetic fields directed some of the matter and gravitational energy of that collapse back out into intense jets, illuminating the surrounding gas with the brightness of a trillion suns.

Billions of years later on the other side of the universe, a certain kind of chemical scum can accurately describe, model, predict and explain what those jets really are.

One physical system, the human brain, contains an accurate working model of an utterly dissimilar one, a quasar. Not just a superficial image but an explanatory model embodying the same mathematical relationships and causal structure. That's knowledge.

And if that weren't amazing enough, the faithfulness of this model is continually increasing. That's the growth of knowledge. So this chemical scum is different.

It models, with ever-increasing precision, the structure of everything. Our planet, thanks to us, is a hub that contains within itself the structural and causal essence of the rest of physical reality.

This doesn't require any special physics or miracle. Just matter and energy - and evidence, with which we chose between rival explanations of what is really out there. In intergalactic space, these three prerequisites are at their lowest ebb: it's empty, cold and dark.

But imagine a solar-system-sized cube of intergalactic space. That cube still contains a million tons of matter. Which is more than enough, say, to build a fusion-powered space station complete with scientists who might be collecting evidence to create an open-ended stream of knowledge, just like us - if the right knowledge were there to start it off.

Therefore we are not in a uniquely hospitable place either. If intergalactic space is capable of creating an open-ended stream of explanations, then so is almost anywhere. And the limiting factor, both there and here, is not physical resources but knowledge.

The Astronomer Royal, Sir Martin Rees, has written a book about our vulnerability to scientific accidents, terrorism using weapons of mass destruction and other dangers: he thinks civilisation has only a 50 per cent chance of surviving this century.

But I believe our survival depends not on chance but on whether we can create the relevant knowledge in time. It always has depended on that, and always will. The vast majority of all species and all civilisations that have ever existed are now extinct.

If we want to be the exception, our only hope is to harness the one feature that distinguishes our species and our civilisation from all others, namely our special relationship with the laws of physics: our ability to create new knowledge.

Take global warming. According to the best available scientific theories, it is too late to avoid a global-warming disaster. For if it's true that our best option is to suppress carbon-dioxide emissions with the Kyoto protocol at a cost of hundreds of billions of pounds, then that's already a disaster by any reasonable measure.

And those measures aren't even purported to solve the problem, merely to postpone it a little. Most likely it was already too late before anyone even knew about it: in the 1970s, the best available science was telling us that industrial emissions were about to precipitate a new Ice Age that would kill billions. The lesson seems so clear that I am baffled that it does not inform public debate: it is that we cannot always know.

No precautions, and no precautionary principle, can avoid problems that we do not yet foresee. Therefore, society needs to shift its stance from problem avoidance to problem fixing. The world is abuzz with plans to cut emissions at all costs.

It ought to be buzzing with plans to cool the planet. Or to thrive on a warmer one. And not at all costs, but efficiently. Some such plans exist: swarms of mirrors in space that would deflect sunlight away from the Earth; encouraging aquatic organisms to eat more carbon dioxide, and so on.

Such problem-fixing ideas, currently mere fringe research, ought to be at the heart of humankind's approach to an unknowable and dangerous future. The ability to put things right, not the impossible prescience needed to stave off all harm in advance, is our only hope of survival.

So take those two stone tablets and carve the two denials I spoke of. On the first, carve: problems are inevitable. And on the second: problems are soluble.

- David Deutsch is a professor of physics at Oxford University. This month he won the $100,000 "Edge of Computation" prize, funded by the philanthropist Jeffrey Epstein, for his work on quantum computers. When he first proposed quantum computation in 1985, it seemed only a theoretical possibility. But the past decade has seen simple quantum computers that many believe will pave the way to a scientific revolution.