By STAFF - THE ECONOMIST
Added: Fri, 19 Nov 2010 14:53:40 UTC

Thanks to Ivan for the link

THE history of physics is littered with the detritus of once-sacred assumptions. As better technology enables more exacting experiments, phenomena that were once scoffed at as impossible become the new norm. For this reason, physicists have long been searching for more sensitive means of probing the realm of antimatter, which theory holds should mirror the familiar world of matter. If precise comparisons of the two were to turn up differences, that would signal a fundamental flaw in understanding of the universe.

Now, a team of scientists working at CERN, Europe’s particle-physics laboratory, has announced a breakthrough in the quest for such tests. In the current issue of Nature, members of the ALPHA experiment report that they have been able to trap a very small amount of antihydrogen—the simplest type of anti-atom—for the first time. Since the hydrogen atom is one of the best-measured systems in all of science, this opens the door to a series of experiments testing just how similar matter and antimatter really are.

The symmetry between particles and antiparticles is woven deep into the foundations of physics. For each particle there should be a corresponding antiparticle with exactly the same mass and lifetime but with an opposite electrical charge. Bring the two together and they annihilate each other in a flash of energy. When anti-electrons (or positrons, as they are usually called) orbit antiprotons and antineutrons, the resulting anti-atoms should have the same energy levels as the common or garden variety. Furthermore, it is thought that gravity should pull on matter and antimatter in just the same way.

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TAGGED: PHYSICS