----------------------------------------
"We've made millions of duckies," Gagnon said.
"Now we want to make an elephant."
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http://www.latimes.com/news/printedition/front/la-sci-collider13apr13,1,467216,full.story
Large Hadron Collider
Fabrice Coffrini / AFP/Getty Images
The collider will send particles cra****ng into each
other at just a wink shy of the speed of light, generating
energies more powerful than the sun.
Europe's enormous $8-billion particle accelerator,
to be activated as early as this summer, is generating
both excitement and fear.
http://www.latimes.com/media/photo/2008-04/37796292.jpg
By John Johnson Jr., Los Angeles Times Staff Writer
April 13, 2008
GENEVA -- Michelangelo L. Mangano, a respected particle physicist who
helped
discover the top quark in 1995, now spends most days trying to convince
people
that his new machine won't destroy the world.
"If it were just crackpots, we could wave them away," the physicist said
in an
interview at the European Organization for Nuclear Research, known by its
French acronym, CERN. "But some are real physicists."
What the critics are in such a lather about is the $8-billion Large Hadron
Collider, a massive assemblage of iron, steel and superconducting wire 300
feet underground in a 17-mile-long circular tunnel on the Franco-Swiss
border.
The most complex piece of scientific equipment ever built, the collider
will
send particles cra****ng into each other at just a wink shy of the speed of
light, generating energies more powerful than the sun.
Scientists like Mangano believe that this instrument, when it begins
operating
as early as this summer, will peer into a looking-glass world that could
contain entrances to extra dimensions and super-massive partners of the
familiar particles that make up our world. One creature that must be
hiding
there, the scientists say, is the Higgs particle, one of the most exotic
undiscovered objects since the yeti.
Critics think the collider could also spawn a black hole that will swallow
Earth.
That could be just an appetizer. Once the collider got going, according to
the
doomsday scenario, it could gobble up distant stars like a child popping
Skittles.
Mangano, who is part of the CERN group studying the safety of the
collider,
doesn't deny the scant possibility that the collider could yield a
mini-black
hole.
By sma****ng protons and lead ions together at energies reaching 14
trillion
electron volts, the Large Hadron Collider will dwarf the world's other
atom-smashers, including the Fermi National Accelerator Laboratory's
mighty
Tevatron in Batavia, Ill.
But that energy, Mangano hastened to add, would be concentrated in a space
thinner than a human hair. Any black hole would be so tiny that it
wouldn't be
able to get its teeth around a bit of local chevre cheese, let alone the
world.
Still, if a black hole were produced at all, "that would be an extremely
spectacular result," he said, a half-smile creeping across his face.
Particle physics
Deep in a dim cavern, UCLA physicist Bob Cousins scrambled onto a catwalk
straddling the six-story detector known as the Compact Muon Solenoid, then
darted up two flights of stairs to another catwalk, where the guts of the
machine materialized out of the half-light.
It looked a little like the inside of a computer suffering from a severe
case
of gigantism. Plates, ****elds and pipes jutted everywhere. Thick knots of
cable extended from the side like mounds of heavy rope on an 18th century
whaling ****p.
"This detector was assembled at the surface and lowered in 15 pieces,"
Cousins
said, pointing to a wide opening above the detector that reached to the
European sky high above.
The heaviest piece weighed 4 million pounds. It took 10 hours to lower the
middle section. At the center of this section is a bulbous extension that
makes the behemoth look like the world's biggest television picture tube.
This
single piece of the collider contains more iron than the Eiffel Tower.
It was all built to probe a beam of particles thinner than a blade of
grass.
Decades ago, scientists figured out that atomic nuclei were made up of
smaller
things than protons and neutrons.
To find those pieces, 20th century physicists came up with an idea that
would
appeal to most 9-year-old boys with a new toy: "Let's smash it and see
what
happens."
Early colliders, like the 9-inch cyclotron created at UC Berkeley in 1931,
sent particles down a circular drag strip and crashed them into a target
to
see what flew out.
From there, particle physics exploded. Larger and more sophisticated
devices
kept packing more energy into the colliding particles, allowing scientists
to
peer deeper into the guts of the atom.
Protons and neutrons, they found, were made up of even smaller particles,
dubbed quarks, which were bound together by another set of particles,
called
gluons. Gluons were part of a larger family, bosons, each of which carries
some form of force. Photons, which make up light, for example, carry the
electromagnetic force.
They found a bestiary of particles -- pions, kaons, deltas and other
exotically named objects -- that existed beyond an atom's nucleus.
Altogether, scientists found dozens of species of elementary particles,
some
composed of pieces so tiny that they make an atom look like a sumo
wrestler,
or a mountain. If a quark measured an inch, an atom would stretch at least
1,000 miles, about the distance from Los Angeles to Denver.
These discoveries enabled physicists to devise a compelling picture of the
universe at the subatomic level. Known as the Standard Model, it is
considered
the most successful scientific theory in history.
It has been able to explain an array of processes through its description
of
the subatomic world and the dynamics of the four essential forces of the
universe: gravity, electromagnetism, the weak force governing radioactive
decay, and the strong nuclear force, which binds protons and neutrons
together
in an atom's nucleus.
But there are problems. First, the Standard Model can't explain why the
universe is composed of matter. According to theory, equal amounts of
matter
and antimatter would have been created in the Big Bang, which created the
universe. As soon as they met, they should have annihilated each other,
releasing photons of light.
"You should end up with a universe with only light," said Tatsuya ****ada,
who
directs another of the four major particle detectors at CERN.
The Standard Model also fails to explain why particles have mass.
"In all our equations, the most fundamental particles that we know matter
is
made of come up massless," said Pauline Gagnon, an Indiana University
physicist who works on a detector known as ATLAS. "We know that's a flaw
in
the Standard Model."
The answers, scientists believe, lie in reactions with the extreme
energies
that occurred during the first moments after the Big Bang. To reach those
energies, they have to push particles as close to the speed of light as
possible.
The CERN collider uses a powerful electromagnetic field to accelerate
particles. "Think of a swing," said Sandor Feher, a fast-talking
Hungarian-born physicist, as he strode through a section of the long
collider
tunnel. "Each time the beam comes around, the field pushes it a little
faster."
At the peak, the hydrogen protons in the new collider will reach
99.9999991%
of the speed of light. Each packet of protons will complete 11,245 laps
around
the collider every second and carry as much power as a speeding train.
The collider will consume as much energy as all the households in Geneva,
running up an annual electric bill of $30 million.
To guide the proton beams through the twin tubes of the collider, 9,600
magnets will continually tune the positively charged protons as they speed
around the collider. The superconducting magnets are cooled with liquid
helium
to minus 456.25 degrees, a whisker above absolute zero.
Whatever objects spring into being in the collider won't last long. They
will
be relatively big and thus inherently unstable and will quickly decay into
more-familiar particles.
Some of these weird objects may travel as much as a millimeter or two
before
decaying, while others will travel less than the diameter of a proton
before
vani****ng in a shower of quarks, gluons, electrons or neutrinos.
Because the detectors will produce millions of collisions every second,
scientists will rely on huge clusters of computers to analyze the results.
The
computers will discard almost all the collisions, preserving only the most
unusual for deeper analysis by humans.
Physicists aren't working completely in the dark. Extra dimensions, for
example, could show themselves by the unusual paths the decaying particles
take as they shoot off into the various layers of the detectors.
If all goes as planned, scientists say, the new collider is likely to
become
one of the greatest engines of discovery in history, far outstripping the
Apollo moon missions and even Charles Darwin's monumental voyage aboard
the
Beagle.
"This is the elevator that will take us to the next floor" of discovery,
Mangano said.
Explaining mass
The first big mystery to fall, theorists expect, will be the explanation
for
mass.
The theory is most often attributed to Scottish physicist Peter Higgs, who
proposed about 40 years ago that the vacuum between the stars is not empty
but
made of a fabric that extends infinitely in all directions.
This fabric, which Mangano compared to the ether that the Victorians
believed
filled outer space, has come to be known as the Higgs field.
"There is something in the vacuum," Mangano said. "As a particle moves, it
interacts with the vacuum and acquires mass." Some physicists compare this
to
a person walking on a dirt path after a rainstorm. As he walks, his boots
get
caked with mud.
If the Higgs field is real, physicists say, it should have a fundamental
particle associated with it. Scientists have named the hypothetical
particle
the Higgs boson.
Fermilab's Tevatron spent years trying to find it. The Large
Electron-Positron
Collider at CERN saw tantalizing hints of the Higgs particle before it was
shut down in 2000 for construction of the new collider.
Physicists are confident of the Higgs boson's existence but think that it
is
just too massive to be produced in smaller colliders.
But how could a collision of tiny particles like protons produce a massive
particle like the Higgs?
In our macro-world, cra****ng things together, like cars, makes big things
into
smaller things, like broken headlights and fenders. But it's different in
the
subatomic world, where cra****ng two Priuses together can produce a
10-wheeler.
"Remember," Gagnon said, "according to Einstein, mass is congealed
energy." In
other words, if you create enough energy in one place, it can remake
itself
into a chunk of mass.
Gagnon compared the particles that have been created in other colliders to
rubber ducks. "We've made millions of duckies," Gagnon said. "Now we want
to
make an elephant."
Because the new collider will be seven times as powerful as the Tevatron,
if
the Higgs boson exists, the CERN collider should find it.
"If we don't find the Higgs, the theorists have a lot of explaining to
do,"
said UCLA postdoctoral student Greg Rakness over lunch in the CERN
cafeteria,
where one can hear conversations in a dozen languages.
The huge burst of energy in particle collisions becomes a kind of time
machine, trans****ting scientists back to the first microseconds after the
Big
Bang.
The universe was only about 200 million miles wide, consisting of a
viscous
cloud of quarks and gluons floating in a searing plasma. As the universe
expanded and cooled, the quarks combined to make protons and neutrons. The
gluons held them together to form the nuclei of atoms.
To re-create this plasma, one of the collider's detectors, known as ALICE,
will accelerate heavy lead ions. One of the heaviest of all elements, each
lead atom contains 82 protons and 125 neutrons.
By pounding these sacks of protons and neutrons together, the scientists
hope
to free the quarks and gluons from their embrace into a free-floating
quark-gluon plasma.
With this re-creation of the early moments of the universe, scientists may
also be able to delve into the unexplained imbalance between matter and
antimatter. So far, experiments have not been able to explain why there's
so
much matter in the universe and no antimatter, beyond what is created in
colliders.
According to experiments, there should be 1020 (100 billion billion) more
photons of light than protons of matter in the universe. In fact, ****ada
said,
the number is closer to 1010. That's a huge amount of unexplained matter
in
the form of galaxies, stars, planets and theoretical physicists.
A detector called the LHCb will try to unravel this mystery by making very
precise measurements of a certain kind of quark that is created in
particle
collisions, the b meson, and its opposite, the anti-b meson.
Black holes
Then there's the matter of black holes.
Harvey Newman, a Caltech physicist who was one of the discoverers of the
gluon
and is leader of the U.S. contingent on the Compact Muon Solenoid
experiment,
said the collider could theoretically produce a mini-black hole by packing
a
tremendous amount of energy into a tiny space.
But he said the black hole would pose no threat because it would last only
10-27 seconds before decaying -- hardly enough time to start gobbling up
the
French countryside.
Critics are not convinced. Just last month, Walter L. Wagner and Luis
Sancho
filed suit in U.S. District Court in Honolulu to block the start-up of the
new
collider until CERN produces a comprehensive safety re****t.
Speaking from Hawaii, Wagner said that despite assurances from scientists
at
CERN and around the world, there was no proof a mini-black hole would
disappear. No one has ever seen it happen, said Wagner, who studied cosmic
ray
physics at UC Berkeley as a young man.
It's just as possible that the tiny black hole would be stable and start
chewing up normal matter, he said.
It could take years for it to become large enough to gobble up the Earth,
but
there's no evidence that can't happen, he said.
His suit for a restraining order is to "preserve the status quo while the
court considers the arguments. In this case, the status quo is Mother
Earth
being here," he said.
Another nightmare possibility is that the collider could produce something
called strange matter, a theoretical substance that some physicists think
exists in the center of the remnants of collapsed stars.
The pressure and temperature are so intense that the protons and electrons
fuse into neutrons, then collapse into a mass of quarks.
Theoretically, the tremendous gravity of strange matter would convert any
ordinary matter it came in contact with.
Mangano said he is now writing a re****t addressing such concerns. He said
that
protests of physics experiments were nothing new.
"Before each new accelerator started, there has been some panic," he said.
Wagner, in fact, filed suit in 1999 to stop Brookhaven National
Laboratory's
Relativistic Heavy Ion Collider in New York. It went ahead and the world
survived -- just as it will this time, according to scientists from
Mangano to
Newman and Stephen Hawking.
"Look," Mangano said, leaning forward in his chair at CERN's sprawling
complex, "what if I told you tomorrow when you shave you will blow up the
world? You laugh. You say that can't happen. But how do you know?
"The only thing we know is that there have been about a million billion
shaves
since people started shaving and the world is still here," he said. "So
all we
can say is the probability of you blowing up the world when you shave
tomorrow
is less than one in 1015."
john.johnson@[EMAIL PROTECTED]
Stories
- Caltech crowd basks in Stephen Hawking radiation
http://www.latimes.com/news/printedition/front/la-sci-hawking12apr12,1,406195.story
2008 Los Angeles Times
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