![]() ![]() “Up until the 1960s it was thought that if the sign of a particle was changed” – from the negative charge of an electron, for example, to the positive charge of a positron – “and if the particle was changed into its mirror image, the new antimatter particle would behave identically to the old ordinary particle. He explains that one of the most challenging puzzles in physics is why the universe is made almost entirely of ordinary matter. If it’s not an energy source, why bother with antimatter? Fajans, who is also a professor of physics at UC Berkeley, has been making antihydrogen for several years as part of the international ALPHA collaboration at CERN, the European laboratory for particle physics headquartered in Geneva, Switzerland. So much energy would be needed to gather enough antihydrogen to fuel a rocket or make a bomb that, with current or even foreseeable technology, the undertaking is utterly implausible.Īs Joel Fajans of Berkeley Lab’s Accelerator and Fusion Research Division (AFRD) puts it, “The Vatican need not fear.” Granted, antimatter may be the ultimate energy source – the energy released by annihilating a mere milligram of antimatter would be equal to 43 metric tons of TNT – but manufacturing antimatter is a voracious energy sink. It takes a lot of care and attention, plus a significant investment of energy, to create even the simplest anti-atom, antihydrogen – which consists of one antiproton orbited by one positron. And while it can be collected in the storage rings of accelerators and light sources or confined by other kinds of electromagnetic traps, most antimatter is transient, gone in the wink of an eye. But these events rarely release enough energy to be noticed unless, like a PET scan operator, you’re looking for it. ![]() ![]() In fact all antiparticles quickly annihilate upon encountering their ordinary-matter counterparts. It’s all around us, all the time, raining down in debris when cosmic rays hit the atmosphere, or used in medical procedures like PET scans, which make images when positrons (anti-electrons) from a radioactive tracer annihilate with ordinary electrons. There’s nothing fictional about antimatter. In Angels and Demons, the new Tom Hanks movie based on the novel by Dan Brown, the race is on to discover a time bomb made of antimatter – what Brown describes as “the ultimate energy source” – before it blows up the Vatican. (Source image: Brookhaven National Laboratory) Antimatter at the doctor’s office: a tracer’s radioactive decays emit positrons, which annihilate with electrons and produce the gamma rays that make this PET scan image possible. ![]()
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