Scientists: Nothing to fear from atom-smasher
By DOUGLAS BIRCH, Associated Press Writer1 hour, 37 minutes ago
The most powerful atom-smasher ever built could make some bizarre
discoveries, such as invisible matter or extra dimensions in space, after it is
switched on in August.
But some critics fear the Large Hadron Collider could exceed physicists'
wildest conjectures: Will it spawn a black hole that could swallow Earth? Or
spit out particles that could turn the planet into a hot dead clump?
Ridiculous, say scientists at the European Organization for Nuclear Research,
known by its French initials CERN — some of whom have been working for a
generation on the $5.8 billion collider, or LHC.
"Obviously, the world will not end when the LHC switches on," said project
leader Lyn Evans.
David Francis, a physicist on the collider's huge ATLAS particle detector,
smiled when asked whether he worried about black holes and hypothetical killer
particles known as strangelets.
"If I thought that this was going to happen, I would be well away from here,"
he said.
The collider basically consists of a ring of supercooled magnets 17 miles in
circumference attached to huge barrel-shaped detectors. The ring, which
straddles the French and Swiss border, is buried 330 feet underground.
The machine, which has been called the largest scientific experiment in
history, isn't expected to begin test runs until August, and ramping up to full
power could take months. But once it is working, it is expected to produce some
startling findings.
Scientists plan to hunt for signs of the invisible "dark matter" and "dark
energy" that make up more than 96 percent of the universe, and hope to glimpse
the elusive Higgs boson, a so-far undiscovered particle thought to give matter
its mass.
The collider could find evidence of extra dimensions, a boon for superstring
theory, which holds that quarks, the particles that make up atoms, are
infinitesimal vibrating strings.
The theory could resolve many of physics' unanswered questions, but requires
about 10 dimensions — far more than the three spatial dimensions our senses
experience.
The safety of the collider, which will generate energies seven times higher
than its most powerful rival, at Fermilab near Chicago, has been debated for
years. The physicist Martin Rees has estimated the chance of an accelerator
producing a global catastrophe at one in 50 million — long odds, to be sure,
but
about the same as winning some lotteries.
By contrast, a CERN team this month issued a report concluding that there is
"no conceivable danger" of a cataclysmic event. The report essentially
confirmed
the findings of a 2003 CERN safety report, and a panel of five prominent
scientists not affiliated with CERN, including one Nobel laureate, endorsed its
conclusions.
Critics of the LHC filed a lawsuit in a Hawaiian court in March seeking to
block its startup, alleging that there was "a significant risk that ...
operation of the Collider may have unintended consequences which could
ultimately result in the destruction of our planet."
One of the plaintiffs, Walter L. Wagner, a physicist and lawyer, said
Wednesday CERN's safety report, released June 20, "has several major flaws,"
and
his views on the risks of using the particle accelerator had not changed.
On Tuesday, U.S. Justice Department lawyers representing the Department of
Energy and the National Science Foundation filed a motion to dismiss the
case.
The two agencies have contributed $531 million to building the collider, and
the NSF has agreed to pay $87 million of its annual operating costs. Hundreds
of
American scientists will participate in the research.
The lawyers called the plaintiffs' allegations "extraordinarily speculative,"
and said "there is no basis for any conceivable threat" from black holes or
other objects the LHC might produce. A hearing on the motion is expected in
late
July or August.
In rebutting doomsday scenarios, CERN scientists point out that cosmic rays
have been bombarding the earth, and triggering collisions similar to those
planned for the collider, since the solar system formed 4.5 billion years ago.
And so far, Earth has survived.
"The LHC is only going to reproduce what nature does every second, what it
has been doing for billions of years," said John Ellis, a British theoretical
physicist at CERN.
Critics like Wagner have said the collisions caused by accelerators could be
more hazardous than those of cosmic rays.
Both may produce micro black holes, subatomic versions of cosmic black holes
— collapsed stars whose gravity fields are so powerful that they can suck in
planets and other stars.
But micro black holes produced by cosmic ray collisions would likely be
traveling so fast they would pass harmlessly through the earth.
Micro black holes produced by a collider, the skeptics theorize, would move
more slowly and might be trapped inside the earth's gravitational field — and
eventually threaten the planet.
Ellis said doomsayers assume that the collider will create micro black holes
in the first place, which he called unlikely. And even if they appeared, he
said, they would instantly evaporate, as predicted by the British physicist
Stephen Hawking.
As for strangelets, CERN scientists point out that they have never been
proven to exist. They said that even if these particles formed inside the
Collider they would quickly break down.
When the LHC is finally at full power, two beams of protons will race around
the huge ring 11,000 times a second in opposite directions. They will travel in
two tubes about the width of fire hoses, speeding through a vacuum that is
colder and emptier than outer space.
Their trajectory will be curved by supercooled magnets — to guide the beams
around the rings and prevent the packets of protons from cutting through the
surrounding magnets like a blowtorch.
The paths of these beams will cross, and a few of the protons in them will
collide, at a series of cylindrical detectors along the ring. The two largest
detectors are essentially huge digital cameras, each weighing thousands of
tons,
capable of taking millions of snapshots a second.
Each year the detectors will generate 15 petabytes of data, the equivalent of
a stack of CDs 12 miles tall. The data will require a high speed global network
of computers for analysis.
Wagner and others filed a lawsuit to halt operation of the Relativistic Heavy
Ion Collider, or RHIC, at the Brookhaven National Laboratory in New York state
in 1999. The courts dismissed the suit.
The leafy campus of CERN, a short drive from the shores of Lake Geneva,
hardly seems like ground zero for doomsday. And locals don't seem overly
concerned. Thousands attended an open house here this spring.
"There is a huge army of scientists who know what they are talking about and
are sleeping quite soundly as far as concerns the LHC," said project leader
Evans.