Large Hadron Collider: Why we're all in love with the 'God particle' machine...

Large Hadron Collider: The world's largest laboratory experiment has begun after the enormous particle smasher was started.

Don't take off your life jacket; the end of the world may yet be nigh, writes Adam Hart-Davis...

When you buy a Ferrari (I am told) you do not drive it out of the showroom at 150mph. Instead, you proceed with caution until you have found out how the brakes work.

The Large Hadron Collider (LHC) is the biggest and most expensive machine ever built, and the drivers are not going to put it into top gear for some time. Indeed, the first real experiments are unlikely to happen for weeks, if not months.

When the physicists do finally turn all the knobs to max and allow two beams of sub-atomic particles to collide head on, they might still generate a black hole that could end the world, but the odds are millions to one against. You are much more likely to be struck by lightning.

Why has the LHC switch-on generated such massive interest? Is it just that frisson of fear about the possible end of the world? Perhaps it's more that Radio 4 chose to devote a whole day to it - indeed, Big Bang Day spread over a week, for some reason best known to the BBC.

But there have been energetic rumblings elsewhere, too, and the sheer excitement of the scientists at Cern (the European Organisation for Nuclear Research near Geneva) seems to have penetrated the consciousness of millions of ordinary people who had never heard of a proton until this week.

So what is the allure of big science? Partly it is simply a question of human curiosity, and that starts young. In Liverpool, a week before Big Bang Day, I gave a talk about the history of science as part of the British Association's Festival of Science.

The questions afterwards all came from small children, who wanted to know: "How big is space?" "If you set off in a rocket, where would you end up?" and "Will there be another Big Bang?"

Changes in the way big scientific breakthroughs are being made are also a factor. A hundred years ago, almost every major step forward in science was taken by individuals: Ernest Rutherford discovered the basic structure of the atom, Albert Einstein pioneered quantum mechanics and invented relativity, Edwin Hubble showed how the universe is expanding, Marie Curie was the great pioneer of radioactivity, and the crystallographer Dorothy Hodgkin discovered the structure of penicillin and other vital compounds.

Even in 1953, when James Watson and Francis Crick, with the help of Rosalind Franklin's data, cracked the structure of DNA, narrowly beating Linus Pauling, none of them was working as part of a big team.

In the next few decades, however, the scenery changed. Technology advanced rapidly and scientific apparatus became more powerful and more expensive. Electron microscopes, mass spectrometers and nuclear magnetic resonance machines were invented and improved - and were shared by groups of scientists.

In a sense, however, it was the space race of the Fifties that saw the launch of big science with the ability to capture the collective imagination. It began in 1957 with the launch of Sputnik 1 by the Russians, rapidly followed by bigger satellites, then a dog called Laika, and the first spaceman, Yuri Gagarin, who became an international hero.

The Americans fought back, and after enormous effort and expense landed Neil Armstrong and Buzz Aldrin on the moon on July 20 1969. This was a colossal triumph for technology and engineering, and probably the most spectacular such event of all time. Meanwhile, space exploration has remained big science that thrills.

There have been many successes by Russian, American, European, Japanese and other space agencies. One spectacular example is the Cassini-Huygens mission (Giovanni Domenico Cassini was an Italian astronomer and Christiaan Huygens was a Dutch scientist who investigated the nature of light and built the first pendulum clock in 1657). It is a joint American-European venture, involving 17 nations and three space agencies, to explore Saturn and its moon Titan.

I was at the European Space Technology Centre in Darmstadt, Germany, when the probe Huygens landed on the surface of Titan on January 14 2005, and the excitement of the scientists and engineers there was spectacular. The mother ship Cassini is still in orbit around Saturn, and has delivered masses of information, including the intriguing fact that another moon, Enceladus, appears to be covered with ice, and might have liquid water under the surface.

Towards the end of the 20th century, scientists acquired not only bigger and better apparatus but also rapidly improving computers and communications - first email and then the internet. This produced a transformation in the way they interacted.

I was told by an engineer at Harvard, who liked working late at night, that his colleagues in Tokyo often sent him a fax early in the morning their time. He enjoyed beginning his reply: "Thank you for your fax of tomorrow..."

In 1990, we saw the beginning of the Human Genome Project (HGP), a collaboration between hundreds of scientists in China, France, Germany, Canada, Britain and the United States. Their goal was to work out the sequence of bases ("letters") of DNA that "spell" out how to make a human being - the human genome.

The people in charge reckoned it would take 15 years, but the technology steadily improved, they became more efficient, and, spurred on by a rival commercial project, led by the American Craig Venter, they actually finished the task two years ahead of schedule.

This was impressive, but what amazed me was the way the research was published. Most scientific results are published in eminent journals such as Nature and Science. During the HGP, however, the results of the publicly funded effort were published on the internet every night, so that they were available to anyone in the world.

The result was that by the time the work was completed, there had already been a dozen spin-off projects, and the whole science of genomics was accelerated.

The completion of the project was announced in a flurry of publicity by Bill Clinton and Tony Blair in 2000, but the HGP did not have quite the impact of Apollo 11, perhaps because it was all done by teams.

People like heroes, and it's more difficult to be thrilled by a thousand scientists in a dozen countries. But, as we have seen this week, if the science is really big, the ideas alone can be enough to fire the imagination.

Will the switch-on of the LHC reawaken a public passion for science? I hope so. It has been built to look for answers to some of the deepest questions that occur to us. Where did the universe come from? Why are we here? Are we alone? Every one of us wants to know the answers.

Shortly after the LHC switch-on, I was interviewed on Radio Scotland. A reporter in Renfrewshire asked a schoolgirl why she was so excited by it. She said that in 20 years' time people would still be talking about the LHC, and she was here, now, witnessing the start of its journey.

Let's hope she's right and that, enthused by this week's flirtation with the cosmos, the public will stay in love with big science.