Air Force pursuing antimatter weapons

Program was touted publicly, then came official gag order RINF NEWS - By Keay Davidson - December 29, 2006 -- 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.... 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. ... http://www.rinf.com/columnists/news/air-force-pursuing-antimatter-weapons FAIR USE NOTICE: This blog contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. 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