Yin, yang. Up-quark, down-quark. Matter, antimatter.
Sounds familiar? Tak salah lagi, Dan Brown dalam
thriller Angels and Demons. Disitu dikisahkan ada
Illuminati yang mencuri senjata antimatter yang
diambil dari lab particle accelerator CERN di Geneva.
Dipakai untuk menghancurkan kota Vatican.
Tapi yang dibawah ini bukan fiksi. Mohon dibaca.
Sambil menunggu waktu berbuka.
Salam,
RM
Air Force pursuing antimatter weapons
Program was touted publicly, then came official gag
order
- Keay Davidson, Chronicle Science Writer
Monday, October 4, 2004
The U.S. Air Force is quietly spending millions of
dollars investigating ways to use a radical power
source -- antimatter, the eerie "mirror" of ordinary
matter -- in future weapons.
The most powerful potential energy source presently
thought to be available to humanity, antimatter is a
term normally heard in science-fiction films and TV
shows, whose heroes fly "antimatter-powered
spaceships" and do battle with "antimatter guns."
But antimatter itself isn't fiction; it actually
exists and has been intensively studied by physicists
since the 1930s. In a sense, matter and antimatter are
the yin and yang of reality: Every type of subatomic
particle has its antimatter counterpart. But when
matter and antimatter collide, they annihilate each
other in an immense burst of energy.
During the Cold War, the Air Force funded numerous
scientific studies of the basic physics of antimatter.
With the knowledge gained, some Air Force insiders are
beginning to think seriously about potential military
uses -- for example, antimatter bombs small enough to
hold in one's hand, and antimatter engines for 24/7
surveillance aircraft.
More cataclysmic possible uses include a new
generation of super weapons -- either pure antimatter
bombs or antimatter-triggered nuclear weapons; the
former wouldn't emit radioactive fallout. Another
possibility is antimatter- powered "electromagnetic
pulse" weapons that could fry an enemy's electric
power grid and communications networks, leaving him
literally in the dark and unable to operate his
society and armed forces.
Following an initial inquiry from The Chronicle this
summer, the Air Force forbade its employees from
publicly discussing the antimatter research program.
Still, details on the program appear in numerous Air
Force documents distributed over the Internet prior to
the ban.
These include an outline of a March 2004 speech by an
Air Force official who, in effect, spilled the beans
about the Air Force's high hopes for antimatter
weapons. On March 24, Kenneth Edwards, director of the
"revolutionary munitions" team at the Munitions
Directorate at Eglin Air Force Base in Florida was
keynote speaker at the NASA Institute for Advanced
Concepts (NIAC) conference in Arlington, Va.
In that talk, Edwards discussed the potential uses of
a type of antimatter called positrons.
Physicists have known about positrons or
"antielectrons" since the early 1930s, when Caltech
scientist Carl Anderson discovered a positron flying
through a detector in his laboratory. That discovery,
and the later discovery of "antiprotons" by Berkeley
scientists in the 1950s, upheld a 1920s theory of
antimatter proposed by physicist Paul Dirac.
In 1929, Dirac suggested that the building blocks of
atoms -- electrons (negatively charged particles) and
protons (positively charged particles) -- have
antimatter counterparts: antielectrons and
antiprotons. One fundamental difference between matter
and antimatter is that their subatomic building blocks
carry opposite electric charges. Thus, while an
ordinary electron is negatively charged, an
antielectron is positively charged (hence the term
positrons, which means "positive electrons"); and
while an ordinary proton is positively charged, an
antiproton is negative.
The real excitement, though, is this: If electrons or
protons collide with their antimatter counterparts,
they annihilate each other. In so doing, they unleash
more energy than any other known energy source, even
thermonuclear bombs.
The energy from colliding positrons and antielectrons
"is 10 billion times ... that of high explosive,"
Edwards explained in his March speech. Moreover, 1
gram of antimatter, about 1/25th of an ounce, would
equal "23 space shuttle fuel tanks of energy." Thus
"positron energy conversion," as he called it, would
be a "revolutionary energy source" of interest to
those who wage war.
It almost defies belief, the amount of explosive force
available in a speck of antimatter -- even a speck
that is too small to see. For example: One millionth
of a gram of positrons contain as much energy as 37.8
kilograms (83 pounds) of TNT, according to Edwards'
March speech. A simple calculation, then, shows that
about 50-millionths of a gram could generate a blast
equal to the explosion (roughly 4,000 pounds of TNT,
according to the FBI) at the Alfred P. Murrah Federal
Building in Oklahoma City in 1995.
Unlike regular nuclear bombs, positron bombs wouldn't
eject plumes of radioactive debris. When large numbers
of positrons and antielectrons collide, the primary
product is an invisible but extremely dangerous burst
of gamma radiation. Thus, in principle, a positron
bomb could be a step toward one of the military's
dreams from the early Cold War: a so-called "clean"
superbomb that could kill large numbers of soldiers
without ejecting radioactive contaminants over the
countryside.
A copy of Edwards' speech onNIAC's Web site emphasizes
this advantage of positron weapons in bright red
letters: "No Nuclear Residue."
But talk of "clean" superbombs worries critics. "
'Clean' nuclear weapons are more dangerous than dirty
ones because they are more likely to be used," said an
e-mail from science historian George Dyson of the
Institute for Advanced Study in Princeton, N.J.,
author of "Project Orion," a 2002 study on a Cold
War-era attempt to design a nuclear spaceship. Still,
Dyson adds, antimatter weapons are "a long, long way
off."
Why so far off? One reason is that at present, there's
no fast way to mass produce large amounts of
antimatter from particle accelerators. With present
techniques, the price tag for 100-billionths of a gram
of antimatter would be $6 billion, according to an
estimate by scientists at NASA's Marshall Space Flight
Center and elsewhere, who hope to launch
antimatter-fueled spaceships.
Another problem is the terribly unruly behavior of
positrons whenever physicists try to corral them into
a special container. Inside these containers, known as
Penning traps, magnetic fields prevent the
antiparticles from contacting the material wall of the
container -- lest they annihilate on contact.
Unfortunately, because like-charged particles repel
each other, the positrons push each other apart and
quickly squirt out of the trap.
If positrons can't be stored for long periods, they're
as useless to the military as an armored personnel
carrier without a gas tank. So Edwards is funding
investigations of ways to make positrons last longer
in storage.
Edwards' point man in that effort is Gerald Smith,
former chairman of physics and Antimatter Project
leader at Pennsylvania State University. Smith now
operates a small firm, Positronics Research LLC, in
Santa Fe, N.M. So far, the Air Force has given Smith
and his colleagues $3.7 million for positron research,
Smith told The Chronicle in August.
Smith is looking to store positrons in a quasi-stable
form called positronium. A positronium "atom" (as
physicists dub it) consists of an electron and
antielectron, orbiting each other. Normally these two
particles would quickly collide and self-annihilate
within a fraction of a second -- but by manipulating
electrical and magnetic fields in their vicinity,
Smith hopes to make positronium atoms last much
longer.
Smith's storage effort is the "world's first attempt
to store large quantities of positronium atoms in a
laboratory experiment," Edwards noted in his March
speech. "If successful, this approach will open the
door to storing militarily significant quantities of
positronium atoms."
Officials at Eglin Air Force Base initially agreed
enthusiastically to try to arrange an interview with
Edwards. "We're all very excited about this
technology," spokesman Rex Swenson at Eglin's
Munitions Directorate told The Chronicle in late July.
But Swenson backed out in August after he was
overruled by higher officials in the Air Force and
Pentagon.
Reached by phone in late September, Edwards repeatedly
declined to be interviewed. His superiors gave him
"strict instructions not to give any interviews
personally. I'm sorry about that -- this (antimatter)
project is sort of my grandchild. ...
"(But) I agree with them (that) we're just not at the
point where we need to be doing any public
interviews."
Air Force spokesman Douglas Karas at the Pentagon also
declined to comment last week.
In the meantime, the Air Force has been investigating
the possibility of making use of a powerful
positron-generating accelerator under development at
Washington State University in Pullman, Wash. One
goal: to see if positrons generated by the accelerator
can be stored for long periods inside a new type of
"antimatter trap" proposed by scientists, including
Washington State physicist Kelvin Lynn, head of the
school's Center for Materials Research.
A new generation of military explosives is worth
developing, and antimatter might fill the bill, Lynn
told The Chronicle: "If we spend another $10 billion
(using ordinary chemical techniques), we're going to
get better high explosives, but the gains are
incremental because we're getting near the theoretical
limits of chemical energy."
Besides, Lynn is enthusiastic about antimatter because
he believes it could propel futuristic space rockets.
"I think," he said, "we need to get off this planet,
because I'm afraid we're going to destroy it."
E-mail Keay Davidson at [EMAIL PROTECTED]
URL:
http://sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/10/04/MNGM393GPK1.DTL
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