Archives

PARIS, Sept 9 (AFP) - The quiet world of physics is being enlivened by a debate over novel theories which suggest human life and even the Universe could be wiped out at a stroke.

Try this end-is-nigh scenario for size: the Universe could change at any time into a jelly that would cause all matter to break up.

Or this one: scientists switch on an atom collider and accidentally create a vicious particle, a "killer strangelet" that gobbles up the Earth.

The ideas may seem to have been lifted straight out of 1950s science fiction. Yet for some thinkers they are genuine -- albeit incredibly remote -- risks, based on a fresh look at the so-called Standard Model of particle physics.

"The universe is perched on a terrible precipice," Benjamin Allanach, research associate at CERN, Europe's Geneva-based particle laboratory, told a science festival in Glasgow, Scotland, on Thursday.

"It could catastrophically tunnel to a new state, disintegrating every atom."

Allanach painted this apocalypse to illustrate revisionist thinking about the Standard Model, a century-old clan of particles such as the neutron, proton and electron.

For him and other physicists, the atomic family may be missing a couple of exotic relatives.

Scientists have long puzzled why the masses of the known fundamental particles are billions of times lighter than calculations of the Universe's mass would indicate.

Some suggest there are sub-atomic particles that we have yet to spot which would make up the difference.

Under the theory of "supersymmetry," every particle we see has a heavier "ghost partner" which has similar but not identical properties.

Allanach speculates that the cooling of the Universe, after the "Big Bang" that created it 15 billion years ago, could suddenly slow down ghost partners to a sub-atomic particle called the quark.

That could turn the quark partners into a kind of jelly that would unleash the ultimate disaster.

The jelly would block movement of light, whose particles, called photons, are responsible for the electric and magnetic forces.

"This would be the death knell of the poor atom, because it is the electric force that binds electrons to the nucleus," Allanach said.

Shed of their electron bonds, the atoms that make up the Universe and all its inhabitants would disintegrate into a dark, whirling havoc.

Luckily, "the probability of this event happening is minuscule," Allanach said. He estimated it to be in the region of one in 13 million squared -- less than the chance of buying two tickets in the same week that each win the top prize in a national lottery.

The "killer strangelet" debate was sparked two years ago by an American theoretical physicist, Frank Wilczek, of the Institute for Advanced Study at Princeton University.

Wilczek sketched the idea in an exchange of letters to the journal Scientific American about the putative risk of starting up a new facility, the Relativistic Heavy Ion Collider (RHIC). This is a huge underground facility on New York's Long Island that smashes atoms together to explore the nature of fundamental matter.

There are six known types of quark, each with offbeat names: up and down, top and bottom and charm and strange.

Wilczek hypothesised that the pressurised superheat of collision could forge a "strangelet," an entirely new particle that would be a mix of stranges and other quarks.

A strangelet with a positive electrical charge would not be a problem.

However, a stable, negative-charged strangelet would be bad news, he said.

When this type of strangelet bumped into a nucleus of ordinary matter, it would "eat" it by binding the nucleus to the strangelet.

Eating positive nuclei would decrease the negative charge of the strangelet, but then random radioactive decay would increase the negative charge again.

When the strangelet had eaten about a million billion nuclei, its weight would pull it down towards the centre of the Earth, where it would continue munching matter.

Eventually, the greedy blob would eat the Earth from the inside out, converting the planet into a giant strangelet about 100 metres (yards) wide, Wilczek suggested.

Wilczek's letter was simply a musing on doomsday scenarios and he himself never believed his tiny glutton was even a remote threat.

Even so, his letter stirred up a media panic -- he got dubbed "Doctor Strangelet" for his pains -- and scientists scrambled to check whether he could be right.

The RHIC's operator, the Brookhaven National Laboratory, set up an independent panel of experts.

They noted that the Moon had been pummelled by powerful cosmic rays with heavy nuclei over the past five billion years and had obviously survived.

They then estimated how many of these rays had smashed into the Moon with the likely energy of collisions at RHIC in order to calculate any risk of creating a dangerous strangelet.

The probability is almost infinitely tiny -- less than 10 to the power of minus 21 during the life of the collider -- and not worth an instant's concern, they said.

Physicists from CERN and the Israel Institute of Technology ran their own calculations, and agreed "beyond reasonable doubt" that atom smashers could not imperil the planet.

News | Business | Features | Editorial | Security
Politics | World | Letters | Sports | Obituaries |

Produced by Lake House
Copyright 2001 The Associated Newspapers of Ceylon Ltd.
Comments and suggestions to :Web Manager