Antimatter Atom

Physicists Take Their Closest Look Yet at an Antimatter Atom

The laws of physics, as experts currently understand them, dictate the following: Every fundamental particle has an antimatter twin. The electron, quark, and muon, for example, are paired with the positron, antiquark, and antimuon, respectively. Each antiparticle weighs exactly the same as its twin, but exhibits precisely the opposite electric charge. If the twins meet each other, they annihilate, often to produce light.

Since physicists discovered the first antimatter particle in 1932, the substance has become, in some ways, quite mundane. Researchers have found that lightning in thunderstorms generates positrons; when they meet nearby electrons, the two annihilate each other. Bananas, which contain trace amounts of radioactive potassium, emit a positron every 75 minutes. When they come into contact with electrons, the two also promptly annihilate, with no noticeable effect./.../

Jeff Hangst's team at CERN found a way to trap and hold antihydrogen for up to 24 hours.COURTESY OF CERN
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Does dark matter matter?

It's perhaps only cosmological physics that can get away with introducing an idea like dark matter — an invisible, so far undefinable form of mass that makes up 27% of the universe. Only five percent of the universe is the matter we can see; after dark matter the remaining 68% is dark energy. Dark matter provides the gravitational force to hold galaxies together; dark energy is the force that continues to cause the universe to expand. (And no, we haven't defined or actually detected dark energy either.)

What makes such concepts concrete is that the universe does not make sense without them. Dark matter and energy must exist or the cosmos would be a very different place. Now, however, researchers from the University of Bonn and the University of Strasbourg have developed a computer model that replaces dark matter with something they call MOND, or Modified Newtonian Dynamics. It's simpler, off-the-shelf physics (the kind Isaac Newton deduced) only positing the argument that the natural attraction between two bodies becomes far more powerful if those bodies are approaching one another very slowly. On the cosmic scale, this can serve as sort of a gravitational force multiplier that allows galaxies to form without a mysterious form of matter being needed in the equation at all. That's the theory anyway, but even its authors admit that it's exceedingly preliminary.

After all, doing away with 27% of the theoretical universe require at least a wee bit more investigative work before you can say you've got it nailed.