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Recent developments in physics suggest the possibility that an experiment at the CERN research facility in Europe will destroy the Earth. CERN is installing a new high-energy particle collider, the Large Hadron Collider (LHC), that is scheduled to begin experiments in 2008. Some of those experiments could be dangerous.

The LHC will use a ring of super-conducing magnets, over five miles in diameter, to accelerate two beams of particles. The beams will collide with tremendous energy. When they collide they will produce many new particles, including, it is expected, particles never before seen by scientists.

Two of the particles it might create, black holes and strangelets, could be dangerous, so dangerous that they could destroy the entire Earth.

Black holes have gravity so strong that even light cannot escape. That is why they are black. In the worst case, that immense gravity could suck in and swallow the entire Earth. Some physicists have published papers predicting (if their theories are true) that CERN will produce a black hole every second.

Strange matter has a different arrangement of quarks than normal matter. Some physicists think it can catalyze the conversion of normal matter into more strange matter. If this reaction gets going, it will convert the entire earth into a small ball of strange matter.

CERN has published a paper asserting several safety factors: [Blaizot et al, see our References section]

1) Black holes are supposed to dissipate via Hawking radiation. However, a new study [Helfner] questions whether Hawking radiation really exists. (Hawking radiation is theoretical, it has never been seen.)

2) A collection of strangelets is supposed to be electrically positive on its surface, and therefore not attract other matter. However, a new study [Peng et al] finds that a collection of strangelets can be electrically negative on its surface.

3) It is claimed that cosmic rays can energy exceeding that of colliders, and they have not caused trouble, suggesting that colliders will not cause trouble either. However, the analogy is not precise. It assumes two things that may not be true. First, cosmic ray center of mass energy exceeding that of colliders has never been measured directly. Measurements that seem to show this are based on showers of secondary particles. Second, the product of a collision between a cosmic ray and an earth particle will always be moving at an appreciable fraction of the speed of light. If it has a small capture radius, it will always pass right through earth like a neutrino. The product of a collider collision can (sometimes) be moving at less than escape velocity from earth. If so, it will fall into earth where it will have forever to accrete other matter. Some calculations show rapid accretion.

4) Physicists have offered a plethora of other reasons why nothing can go wrong. See our section, "Help us find a limit to this model." Some of these reasons may prove definitive. At the moment we think they need work. We encourage more work in this area.

It is useful to think of reasons why we may be safe. However, we ask people who do so, to please think out these reasons carefully before they are used to assure the public that nothing can possibly go wrong. The precautionary principle asserts that proponents of risky experiments should prove they are safe. It is unethical to do so with reasons that do not hold water. We are talking about destruction of Earth here. We do not want to make a mistake.

One physicist published a popular article assuring the public that nothing can go wrong. His main reason, not mentioned in the article, was that he believes that there is no such thing as a black hole. His reason for this belief: "When equations go to infinity, that is a sign that there is something wrong with the equation." He may be right. However, we should not base the safety of the entire earth on a theory that has a reasonable chance of being false.

Reporters and editors, when considering this story, often ask a physicist. That physicist often repeats one of the rather questionable reasons why nothing can go wrong. Reporters have an obligation to follow up.

CERN's Chief Scientific Officer, Jos Engelen, was quoted in the New Yorker recently (5/14/07) as instructing CERN scientists to say that the risk is zero.

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