This week: the legacy of a great scientist It has been a sad week for the science community with the death of John A. Wheeler on Sunday at his home in Hightstown, New Jersey, at the age of 96. Wheeler was a historic figure in the annals of physics, a man who had arguments on equal terms with such greats as Albert Einstein and Niels Bohr, the teacher of a multitude of famous scientists, including Richard Feynman. Wheeler rejuvenated general relativity and made it an experimental laboratory subject for students rather than just a jumble of mathematical curiosities on paper. He helped envisage the splitting of the atom that would lead to the nuclear world we live in today. He was a member of the Manhattan Project that spawned the nuclear bomb that ended the second world war. When younger, he had been greatly disturbed at the notion that Einstein's theory predicted that when a star of sufficient mass died, it would collapse in on itself and become so dense that all nearby mass and even light could not escape. Space would be forever warped at this point, which would be infinitely dense and infinitely curved. This is described as a singularity. Wheeler eventually got around his personal resistance to the logic of Einstein's theories and became a lecturer on the topic. He coined the term 'black hole' during a conference to help dramatise the spectacular ending of a star's life. It became an everyday term that has sparked the imagination of millions of science-fiction fans. A new particle accelerator is being built in Switzerland that is to begin operating within the year. The basic purpose of the gargantuan construction is to smash atomic particles together and watch the results of the collisions. With enough force, the accelerator will not only be able to split atoms into smaller constituent particles and release weird new energies, it will be able to create miniature black holes. In the past, it was believed that to accelerate a particle fast enough to create a black hole, you would need an accelerator the size of the solar system. But now scientists think a smaller one will probably do. Imagine if a black hole were created in a laboratory and escaped the particle accelerator because it was so small it could fit through the space between electrons and protons and pass through a lead wall as if it were air. This mini black hole would attract and accumulate matter at a rapidly increasing rate. The cascading reaction would absorb more and more matter, and suddenly, poof! One second we are standing around leading our menial lives, the next moment it's all gone, the Earth and all its inhabitants squeezed into a little hole the size of a pinhead. Fortunately, the likelihood of such an event is rather low, because the predicted lifespan of a mini black hole is a tiny fraction of a second: it will dissipate virtually at the moment of its creation because it will emit all its energy in the form of what is known as Hawking radiation (after physicist Stephen Hawking). There is a small chance that these predictions are wrong. Hawking radiation is a theory with no experimental evidence, so no one know what surprises await the scientists, and us, when they turn that accelerator switch on. Also, if it does turn out that a mini black hole escapes and burrows to the centre of the Earth, it may take hundreds of thousands of years for it to mature, giving us ample time either to research it or for the human race to become extinct on its own. Technically speaking, we are bombarded with high-energy particles every day from outer space, and these could also create mini black holes that could engulf us in Armageddon. But the Earth is still here 4.5 billion years after it came into existence, so presumably this is rather unlikely. Modern physics is a frontier of exploration. New phenomena and discoveries are the constant, and they are invariably weird. For me the field is romantic and inspiring, the reason for my love of science and exploration. Wheeler described his role in physics in an interview 25 years ago: 'If there's one thing in physics I feel more responsible for than any other, it's this perception of how everything fits together. 'I like to think of myself as having a sense of judgment. I'm willing to go anywhere, talk to anybody, ask any question that will make headway. 'I confess to being an optimist about things, especially about some day being able to understand how things are put together. So many young people are forced to specialise in one line or another that a young person can't afford to try and cover this waterfront - only an old fogey who can afford to make a fool of himself. 'If I don't, who will?'