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Recent developments in physics suggest the possibility that experiments at the CERN research facility in Europe will destroy the Earth. CERN tested a new high-energy particle collider, the Large Hadron Collider (LHC), on September 10, 2008. Before collision experiments could begin, a magnet coolant failure postponed any experiments until 2009. 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. 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.
The theories that enable disaster are speculative. However, the disaster they enable if true is extreme.
In response to criticism, collider advocates have published three studies saying that nothing could possibly go wrong. Three studies were necessary because safety factors claimed by the first two studies eroded shortly after the studies were published.
The first study was posted before startup of the Relativistic Heavy Ion Collider at Brookhaven in 2000. [Busza et al, see our References section.] It claimed that black hole production required energy beyond the reach of any collider. Shortly afterward, physics papers appeared, based on new theory, predicting creation of black holes at colliders (but saying we are safe due to Hawking radiation.) [Dimopoulos & Landsberg] [Giddings & Thomas]
The second study was published by CERN in 2003. [Blaizot et al] It anticipated black hole production, but claimed that black holes would dissipate via Hawking radiation. Shortly afterward, and unrelated to the collider risk issue, physics papers appeared questioning the fundamental theory behind Hawking radiation, a radiation that has never been observed. [Helfer] [Unruh & Schützhold]
Both studies said that collection of strangelets would 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.
Despite this erosion of safety factors, collider advocates continued to cite these safety papers to support their assertion that nothing could possibly go wrong.
Finally, CERN was persuaded to do a third safety study. Three months before startup, they released a report that is actually fairly good. [Ellis et al] A supplementary paper by Giddings and Mangano [in References] tentatively agreed with many of the points made by collider critics, and went beyond them to find new safety factors. For example, an analogy between colliders and cosmic rays was presented by collider advocates to demonstrate safety. If colliders collisions could cause trouble, cosmic ray collisions should already have done so. However, critics said that this was a false analogy. Cosmic-ray-created black holes would be moving rapidly and could be modeled to consistently zip through earth like neutrinos without stopping, whereas collider-created black holes would be slower and should occasionally stop and cause trouble. Giddings and Mangano tentatively agreed with critics on this point, but presented an equation that purported to show that cosmic-ray- created black holes would stop in neutron stars if they could cause trouble in earth, making neutron star lifetimes shorter than observed. Therefore colliders should not cause trouble. Subsequently two scientists, Rössler and Plaga, [in References] posted papers positing separate models in which colliders do cause trouble. Plaga's paper was answered by Giddings and Mangano. This answer was subsequently answered by Plaga. [not yet in References]
It is not unlikely that colliders will turn out to be safe. However, the current "standard model" of physics is known to be incomplete, so there is some chance that safety factors will erode again.
Toby Ord presented at he Future of Humanity conference at Oxford July 2008 saying that the probability that physics is wrong about the collider issue is higher that the very low probabilities supposedly computed by some using standard physics. Also, risk assessment for this issue has been far from best practices. [Leggett, 2008] Finally, even a small probability of trouble produces a high negative expected value (probability times cost), the criteria of choice for decision theory, when the cost as issue is the loss of earth.