Are we all going to die next Wednesday?

Two nightmare scenarios, two ends of the world. In the first, there is little warning. For maybe a month there would be no sign that life was about to come to an abrupt and nasty end for all living things on Earth.



Then, earthquakes would start unexpectedly, alerting geologists that something terrible, unimaginable, was amiss.



After a few days, these seismic disturbances would reach catastrophic proportions.



Cities would be levelled, the oceans would rise and wash in a series of mega-tsunamis that would attack the world's coasts, killing millions.



Is the end of the world nigh? Doom-mongers fear the consequences of scientists replicating the Big Bang

The fact that the earthquakes were striking randomly, not along well-known geological faultlines, would be proof that something devastating was afoot.



Finally, the end would come, in a disaster of Biblical scale. The Earth would literally start to crack up.



Molten lava would wash over the land and the seas would start to boil.



Mega-hurricanes would level buildings and forests the world over. Eventually, mountains would crumble as the Earth's crust continued to disintegrate.



The fabric of the planet itself would start to disappear, trillions of tonnes of rock, water, air and life sucked into a whirlpool of unimaginable force.



From space, our blue-and-white home would appear to vanish down a plughole in a flash of light.

At least in this scenario we would have a little time, perhaps, to come to terms with the end.



However, a second doomsday scenario is even more terrifying. There would be no warning at all.

In an instant - about one-twentieth of a second - the entire Earth would simply vanish from space.



Less than two seconds later, the Moon would follow suit. Eight minutes later, the Sun would be ripped apart, followed by the rest of the planets in the solar system and onwards, a wave of destruction caused by a rent in the fabric of space itself, spreading out from our world at the speed of light.

Any extra-terrestrials out there would die too, in due course. And there would be nothing technology could do about it.



But why should we now be worrying about such possible causes of Armageddon?



The answer is a gargantuan machine - the largest, most expensive scientific experiment in history, the 'Large Hadron Collider', to be turned on next Wednesday.



Doom? The Large Hadron Collider CMS detector under construction

Although it was designed to answer the fundamental questions of life, some people have claimed that it could end up destroying the entire cosmos.



This gigantic £4 billion-plus atom-smasher has been built under the Swiss-French border near Geneva, and is the most powerful device ever built for probing the secrets of the atom and the forces and particles which make up our Universe.



It is a staggering device, occupying a train-sized tunnel 18 miles long, buried 300ft underground, studded with gigantic, cathedral-sized ring-shaped detectors where collisions between packets of 'heavy' subatomic particles, 'hadrons', will take place in the hope that the innermost workings of matter and energy will be revealed.



The LHC is, arguably, the most impressive machine ever built by Mankind.



But a few people are convinced that it should never be turned on. A lawsuit has been lodged at the European Court For Human Rights by a small group of maverick scientists.



They claim there is a small - but not zero - chance that when the LHC is activated it will create either a mini-black hole which would fall into the ground and swallow the Earth from within (scenario one).



Or, even more bizarrely, trigger a catastrophic chain reaction in the very fabric of space and time itself, which would rip apart the entire universe like the skin of a bursting balloon (scenario two).



Bizarrely, this group, led by a German chemist called Otto Rossler, are using the European Convention on human rights to argue that, should the LHC destroy the entire Universe, it would 'violate the right to life and right to private family life'.



In fact, since 1994, when the collider was first mooted by the multi-national European nuclear research organisation (CERN), a small number of doomsayers have claimed that by replicating the conditions pertaining at the start of the universe (Big Bang), about 13,700 million years ago, there would be a small but real risk an unstoppable cataclysm would take place.



This is not a threat taken seriously by the scientists at CERN. When I visited the place a couple of years ago, to see the collider being built, any mention of mini-black holes and other risks elicited only raised eyebrows and shrugs of derision.



The LHC was not designed to destroy the universe, of course, but to fill in some of the embarrassingly large gaps that still run through our basic understanding of physics and how the universe works.



It could discover, for instance, what most of the Universe is actually made of.



The ordinary 'stuff' that we see around us - the atoms and molecules of water, carbon, iron, oxygen and the rest that make up our bodies, the planet Earth, the Moon, the other planets, the Sun and all the stars - actually accounts for only about one part in 25 of the total 'ingredients' of the cosmos.



Astronomers know that something else, invisible and mysterious, must pervade every inch of space, its subtle gravity affecting the movements of the galaxy.



This material - no one really has a clue what it is - has been dubbed 'dark matter' and it is hoped that the collider just might shed some light on what it is, perhaps uncovering a new type of particle.



Perhaps more embarrassingly, we don't know what it is that gives even ordinary matter its mass.



In the 1960s, British physicist Peter Higgs proposed the existence of a new particle, now known as the 'Higgs Particle', which effectively lends 'weight' to the stuff of the universe.



So important and fundamental is this hypothetical entity that it has been dubbed the 'God particle'.



It is hoped that if Higgs is right, the collider could finally clear up this mystery and, as a result of its super-powerful collisions, traces of this particle could emerge.



That alone would, in itself, be justification for a large chunk of that £4 billion outlay. By simulating the Big Bang, it is hoped the LHC will act as a 'universe in a test tube', allowing scientists to examine a whole suite of exotic subatomic particles and forces and to go some way to completing the work started by Einstein and the other giants of 20th-century physics.



So is there really a chance that the scientists have made a terrible miscalculation and that their new toy could inadvertently kill us all?

Happily, the simple answer is no. CERN's scientists have in fact commissioned several safety reviews (such as those that have taken place before other big particle accelerators have been turned on).



All have concluded that there is no measurable risk whatsoever. Perhaps the best argument against the LHC doomsday scenario is that cosmic rays - natural high-energy particles from space - smash into the Earth's atmosphere all the time with far, far more energy than will be generated by this machine.



If it were possible to create a dangerous black hole by simply bashing atomic particles together, this would have happened naturally long ago, and we wouldn't be here to build this particle accelerator in the first place. So we are safe.

In fact, what the scientists at CERN really fear is not the end of the world, but that their machine simply isn't big or powerful enough to uncover anything new - that to probe the deepest secrets of the cosmos they will have to ask for yet more cash to build something on an even greater scale.



Either that, or their equations are simply wrong and a whole new approach is needed, despite the billions they have spent.



Not a doomsday for Earth, perhaps, but a catastrophe for physics.

As for the rest of us, we have to hope that the scientists have done their sums right - and keep our fingers crossed next Wednesday.