Black holes possible
The accelerator, known as the Large Hadron Collider, is under
construction in an underground circular tunnel nearly 17 miles long
at CERN, the world's largest physics laboratory, near Geneva,
Switzerland.
At its maximum, each particle beam the collider fires will pack as
much energy as a 400-ton train traveling at 120 mph.
By smashing particles together and investigating the debris,
scientists hope to help solve mysteries such as the origin of mass
and why there is more matter than antimatter in the universe.
If theories about the universe containing extra dimensions other
than those of space and time are correct, the accelerator might
also generate black holes, Landsberg and his colleague Savas
Dimopoulos at Stanford University in California calculated in
2001.
Physicists Steve Giddings at the University of California, Santa
Barbara and Scott Thomas at Stanford reached similar
conclusions.
Black holes possess gravitational fields so strong that nothing can
escape them, not even light. They normally form when the remains of
a dead star collapse under their own gravity, squeezing their mass
together.
Although black holes can't be seen, astronomers infer their
existence by the gravitational effects they have on gas and stars
around them.
Making black holes
Some models of the universe suggest extra dimensions of reality
exist, each folded up into sizes ranging from as tiny as a proton,
or roughly a millionth of a billionth of a meter, to as big as a
fraction of a millimeter.
At distances comparable to the size of these extra dimensions,
gravity becomes far stronger, these models suggest.
If this is true, the collider will cram enough energy together to
initiate gravitational collapses that produce black holes.
If any of the models are right, the accelerator should create a
black hole anywhere from every second to every day, each roughly
possessing 5,000 times the mass of a proton and each a thousandth
of a proton in size or smaller, Landsberg said.
Still, any fears that such black holes will consume the Earth are
groundless, Landsberg said.
For one thing, theoretical physicist Stephen Hawking calculated all
black holes should emit radiation, and that tiny black holes should
lose more mass than they absorb, evaporating within a billionth of
a trillionth of a trillionth of a second, "before they could gobble
up any significant amount of matter," Landsberg said.
Not destroyed yet
CERN spokesman and former research physicist James Gillies also
pointed out that Earth is bathed with cosmic rays powerful enough
to create black holes all the time, and the planet hasn't been
destroyed yet.
"Still, let's assume that even if Hawking is a genius, he's wrong,
and that such black holes are more stable," Landsberg said.
Nearly all of the black holes will be traveling fast enough from
the accelerator to escape Earth's gravity.
"Even if you produced 10 million black holes a year, only 10 would
basically get trapped, orbiting around its center," Landsberg
said.
However, such trapped black holes are so tiny, they could pass
through a block of iron the distance from the Earth to the Moon and
not hit anything. They would each take about 100 hours to gobble up
one proton.
At that rate, even if one did not take into account the fact that
each black hole would slow down every time it gobbled up a proton,
and thus suck down matter at an even slower rate, "about 100
protons would be destroyed every year by such a black hole, so it
would take much more than the age of universe to destroy even one
milligram of Earth material," Landsberg concluded. "It's quite hard
to destroy the Earth."
If the Large Hadron Collider does create black holes, not only will
it prove that extra dimensions of the universe exist, but the
radiation that decaying black holes emit could yield clues that
help finally unite all the current ideas about the forces of nature
under a "theory of everything."