By late summer this year the enormous particle accelerator at CERN, known as the Large Hadron Collider or LHC, will be fired up and ready to begin its experiments. What will be happening in the accelerator is hardly understood, and the complacency displayed by those ready to play with such unknown and unthinkably powerful forces is manifest. There was a brief internal inquiry as to safety in 2002 and a report was published stating that there was no problem. So that's all right then. Oh, and there is to be an updated version of this report - but this is only going to be published after the machine has been operating for months.

Unfortunately particle physics is seen by the average person as some kind of esoteric religion with Stephen Hawking as its high priest. It's all so clever and sacred that we ordinary mortals couldn't even begin to discuss it and must merely stand by oohing and aahing as if at a firework display.

I am a layperson without even a science 'A' level to my name; however I can grasp that there is a small but undeniable risk of utter destruction involved in the pursuit of CERN's goals. Never mind dismissing this as 'like winning the lottery three times in a row', as Professor Frank Close has been quoted as saying. The risk exists that the experiment will have ultimately evil results and this should be considered very seriously.

If black holes are created at CERN and Stephen Hawking is wrong about their immediate evaporation (and despite his position in the public mind as the pope of popular science he is only human and fallible) we have been given no explanation as to what could be done to contain them. They could travel through the earth back and forth collecting matter until they gain enough size to begin tearing the earth apart.

Just imagine - not the deaths of individuals, or of nations or event the extinction of humanity but the destruction of the earth itself. Goodbye to our past, present and future, the products of all our civilizations wiped out as though they had never been and all future potential gone for ever.

Or imagine an even worse scenario, the reduction of the entire universe to another, unknown state of matter, because of a chain reaction started by these experiments. This could in theory happen if our universe does not exist in the most stable possible state.

The human mind does tend to boggle at these concepts and a common reaction is to throw up one's hands or make a joke of it all along the lines that there will be no reproaches afterwards if the scientists get it wrong. My reaction is one of horror that we can sleepwalk into such a situation. No one has really discussed this with the public, no one has voted for or against it despite the fact that it concerns every one of us in the most fundamental way.

It is said by way of a comparison that the scientists working on the Manhattan Project feared that their bomb might ignite the atmosphere and kill all life on earth but decided to take that chance. I would answer that, whether you think this was defensible or not, firstly, we do not have the urgent reasons they had to take this risk.

As far as any of us know the only justification for the CERN experiments is 'pure science'. Secondly even if life on earth had been extinguished, as terrible as that would have been, at least it would have had a chance to rise again.

It is further said that these experiments are only a weak imitation of what already occurs in nature. I would answer that the CERN experiments are artificial and isolated, and there is no knowing which added or missing factors will affect the outcome compared to what happens in nature. One vital point, not addressed in the safety report, is that any black holes created would be stationary rather than moving at an immense speed as in nature; they would thus be free to accelerate towards the earth's core, decelerate towards the opposing crust, reaccelerate towards the core, and so on.

Please note that there is a presumption to upgrade the collider to higher energy levels in ten years' time. Even if we get away with running the LHC as it stands - and any ill effects are likely to be insidious, as described above, rather than immediate - skating on thinner and thinner ice makes disaster more and more likely.

Although the odds of an adverse effect are actually unquantifiable owing to all the unknowns, the CERN scientists have commented publicly on these odds since the 2002 report; however, their figures are seemingly pulled from the air. Professor Close's example of winning the lottery three times would give you a chance of 14 million cubed. Where does that come from? According to Wikipaedia, Lord Rees, Astronomer Royal and President of the Royal Society, claimed in his 2003 book 'Our Final Hour' that the chance of things going wrong via a particle accelerator was 'one in 50 million'. Rather a high risk I would have thought, and very far removed from 14 million cubed to one. Theoretical physicists are not experts in risk assessment.

It doesn't take great scientific knowledge, only a modicum of intelligence, common sense and healthy skepticism to see that there should be a moratorium on such high energy particle colliders until a very great deal more is known about what exactly we are dealing with and how it works. This is a wager that is far to great to lay, even if the odds are as good as some of our scientist bookies would have us believe.

Yours faithfully

Mrs Justine Jones