Not unsafe: The RHIC at Brookhaven

QGP is an unknown realm; how much so became apparent in 1999, at a time when the construction of RHIC was nearing completion. Just as experimenters were bracing for the task ahead, some people raised an alarm, saying that a bunch of enthusiasts were ?boldly going where it may be unsafe to go.? What if they created something that could not be controlled?

The RHIC experiment might end up producing miniature black holes, said the alarmists, taking a cue from the theories of the Cambridge University physicist Stephen Hawking. In the 1970s Hawking postulated that in the early moments of the Big Bang mini black holes might have been present. Although they no longer exist in our region of the Universe, such mini monsters, said Hawking, could be created by smashing a proton into an anti-proton with enough energy.

If one were created near a large congregation of mass, and if it started absorbing that mass before exploding, the black hole could continue to grow. If this happened on earth, the alarmists argued, the mini black hole would be drawn by gravity towards the centre of this planet, absorbing matter along the way and devouring the entire planet within minutes.

As the apprehensions made headlines, opinions were sought from experts. One among them was Prof. Frank Wilczek ? winner of last year?s Nobel Prize in physics ? from the Institute for Advanced Study in Princeton, US. He likened the scare with the fear of the unknown. ?Whenever we explore new physical (or chemical, or biological) phenomena, questions arise regarding whether we might unwittingly trigger some catastrophe,? said Wilczek. ?Scientists must take such possibilities very seriously ? even if the risks seem remote ? because an error might have devastating consequences.?

According to Wilczek, in the case of RHIC, dangerous surprises seemed extremely unlikely. Nuclear collisions with larger energies take place regularly as cosmic rays rain down on our atmosphere; so if a disaster were possible it would have already occurred. The energy densities and volumes that RHIC was aiming at were not large enough to produce strong gravitational fields, he pointed out.

Wilczek admitted that there was ?a speculative but quite respectable possibility? that subatomic chunks of a new stable form of matter called strangelets might be produced in the RHIC experiment. One might be concerned about a scenario in which a strangelet grew by incorporating and transforming the ordinary matter in its surrounding. ?But if strangelets exist at all, they are not aggressive, and they will start out very, very small,? said Wilczek. ?So here again a doomsday scenario is not plausible.?

Wilczek?s disclaimer did not end the debate. The Sunday Times of London ran a story with a headline ?Big Bang machine could destroy earth?. Already unsettled by reports of chemical and radioactive leaks from the BNL facilities, Long Island residents intensified their campaign against RHIC.

Not only did this force the BNL staffers to go to the public, speaking at local schools and community events, but BNL director John Marburger (who?s now the scientific advisor to US President George W. Bush) also formed a committee to investigate whether the RHIC project could go disastrously wrong. The committee concluded that ?catastrophic scenarios at RHIC are firmly excluded by existing empirical evidence, compelling theoretical arguments, or both.?

The scaremongering over the RHIC experiments was reminiscent of the apprehensions during the initial days of making of the atom bombs that fell on Hiroshima and Nagasaki. In 1942, Edward Teller, who in later life turned out to be the staunchest supporter of the hydrogen bomb, said that the tremendous heat generated by a bomb might ignite the earth?s atmosphere.

Alarmed by Teller?s apprehension, his boss, Robert J. Oppenheimer, ordered an enquiry and its report, codenamed LA-602, was kept secret. The study, made public only in 1973, however, revealed no threat to the earth. According to experts, the atomic fireball would cool down even before it could ignite the atmosphere for a self-sustaining fire.

P.G.