| Pale blue dot: Earth's fate precariously depends on scientists' role as activists
Albert Einstein's achievements in his annus mirabilis a hundred years ago, and ' even more ' his theory of general relativity that emerged in 1915 gave him a status in the scientific pantheon matched only by Newton.
Einstein's great work was over well before he was 40. Photos from that time show him as a nattily dressed young professor, though we're more familiar with the image of the old Einstein ' the benign and unkempt sage of poster and T-shirt. But Einstein didn't rest on his laurels in old age: he worked till his dying day seeking a unified theory of nature's forces. At that time it was, we now realise, a premature quest which was doomed from the start. Cynics have said that Einstein might as well have gone fishing from 1920 onwards.
Although there's something rather noble about the way he persevered in his attempts to reach far beyond his grasp, in some respects the Einstein cult sends the wrong signal. It unduly exalts 'armchair theory', which by itself would achieve little. We're no wiser than Aristotle was, and the advance of science ste-ms mainly from new technology and new instruments ' in symbiosis, of course, with theory and insight.
The intense focus on Einstein also constricts our view of the sheer breadth of science and where it is taking us. One great challenge is to succeed where Einstein failed ' to discover a unified theory of all the basic forces that govern the natural world. But our everyday world presents intellectual challenges just as daunting as those of the cosmos and the quantum.
What makes things hard to understand is their intricate internal structure: celestial objects are simpler even than insects, let alone human beings. Ever since Newton, we've understood the 'clockwork' of planetary orbits; modern cosmologists make confident inferences about what happens billions of light years away. In contrast, scientists still can't agree on what food is good for us. There is a real sense in which dietetics is harder than cosmology.
Einstein is an inspiration to aspiring theorists and cosmologists, but we need high-profile role models in more practical fields, too. Most people can readily name great 19th century engineers ' Brunel, for instance. Those who've given us today's amazing technologies deserve as much acclaim. (Indeed, engineers are even worse at PR than physicists ' there seems no reason why their leading practitioners shouldn't have the same glamourous profile as our more celebrated architects.)
But there are other reasons ' going beyond science ' why the 'old' Einstein has such wide cultural resonance. Despite the failure of his unified theory, his fame gave him influence on public affairs. When the nuclear threat first loomed over us, he was an inspiration and moral compass to other scientists. Back in 1955, just a week before he died, he co-signed, with Bertrand Russell, a manifesto that launched the Pugwash conferences, an international forum for scientific discussions on disarmament and world affairs.
It was Joseph Rotblat, winner of the Nobel peace prize in 1995, who organised that manifesto ' he's happily still active aged 96. Rotblat was among those who worked at Los Alamos on the project that led to the atomic bomb. These people belonged to the 'golden generation' of physicists who established our modern view of atoms and nuclei. After the Second World War, many of them set an admirable example for researchers in any branch of science that has grave societal impact. The likes of Einstein and Rotblat didn't say that they were 'just scientists' and that the use made of their work was up to politicians. They deemed it their duty to alert the public to the implications of their work, and to campaign for arms control.
Twenty-first century science will offer immense potential benefits, but will confront us with ethical dilemmas and threats. In our interconnected world, where technology empowers us more than ever, we're vulnerable to new kinds of risk ' events of seemingly low probability, but of such catastrophic consequences that their reduction should be high on the agenda. These will come from bio, cyber and environmental science, as well as from physics. In all these fields society will need latter-day counterparts of Joseph Rotblat. University scientists and independent entrepreneurs have a special obligation because they have more freedom than civil servants, or company employees subject to commercial pressure. Such individuals can sensitise our consciences, and catalyse dialogues between scientists and the wider public, especially about long-term issues.
The political planning-horizon is seldom longer than the 20 years of the economic discount rate ' often it is just the next election. But we need a much longer time-horizon when discussing energy, climate change and so forth. And those discussing the disposal of nuclear waste talk with a straight face about what might happen in thousands of years. But even a millennium is a mere 'instant' in our planet's history. The stupendous time spans of the evolutionary past are now familiar. But what's not yet part of common culture is the concept that the vistas stretching ahead are even longer ' the future allows time, potentially, for further evolution as dramatic as what's led from the very first life to humans. It will not be humans who witness the demise of the sun six billion years hence: it will be entities as different from us as we are from bacteria.
When Einstein died, a memorable tribute to his global status came from an American cartoonist called Herblock. He depicted the earth viewed from afar. It bears a plaque reading 'Albert Einstein lived here'.
Since the 1960s, we've become familiar with real images of the earth as viewed from space ' its fragile biosphere contrasting with the sterile moonscape where the astronauts left their footprints. Suppose some aliens had been watching our planet for its entire history, what would they have seen' Over nearly all that immense time, 4.5 billion years, earth's appearance would have altered very gradually. The continents drifted; the ice cover waxed and waned; successive species emerged, evolved and became extinct. But in just a tiny sliver of the earth's history ' the last one millionth part, a few thousand years ' the patterns of vegetation altered much faster than before. This signalled the start of agriculture. The pace of change accelerated as human populations rose. But then there were other changes, even more abrupt. Within 50 years ' little more than one hundredth of a millionth of the earth's age, the carbon dioxide in the atmosphere began to rise anomalously fast. The planet became an intense emitter of radio waves (the total output from all TV, cell phone, and radar transmissions). And something else happened: metallic objects ' albeit very small ones, a few tons at most ' left the planet's surface and escaped the biosphere completely. Some were propelled into orbits around the earth; some journeyed to the moon and planets.
If they understood astrophysics, the aliens could confidently predict that the biosphere would face doom in another six billion years, when the sun dies. But could they have predicted this unprecedented spike less than halfway through the earth's life ' these human-induced alterations occupying, overall, less than a millionth of the elapsed lifetime and seemingly occurring with runaway speed'
If they continued to keep watch, what might these hypothetical aliens witness in the next hundred years' Will a final spasm be followed by silence' Or will the planet itself stabilise' And will some of the small metallic objects launched from the earth spawn new oases of life elsewhere'
The answer will depend on collective human actions, and on how we choose to apply our expanding scientific knowledge. These choices could affect the far future of our 'pale blue dot' in the cosmos. We need the kind of perspective that Einstein himself espoused ' global, humanistic and long-term. If we choose wisely, Einstein's legacy will resonate through this century and indeed far beyond.
(Sir Martin Rees, UK's Astronomer Royal, is the winner of the Michael Faraday Prize, awarded annually by the Royal Society for excellence in communicating scientific ideas in lay terms)
The Daily Telegraph