Scientists Blast Antimatter Atoms With a Laser For The First Time (npr.org)

For the first time, researchers from Indiana University were able to blast antimatter atoms with a laser to measure the light emitted from the anti-atoms. The researchers hope to answer one of the big mysteries of our universe: Why, in the early universe, did antimatter lose out to regular old matter? NPR reports: "The first time I heard about antimatter was on Star Trek, when I was a kid," says Jeffrey Hangst, a physicist at Aarhus University in Denmark. "I was intrigued by what it was and then kind of shocked to learn that it was a real thing in physics." He founded a research group called ALPHA at CERN, Europe's premier particle physics laboratory near Geneva, that is devoted to studying antimatter. That's a tricky thing to do because antimatter isn't like the regular matter you see around you every day. At the subatomic level, antimatter is pretty much the complete opposite -- instead of having a negative charge, for example, its electrons have a positive charge. And whenever antimatter comes into contact with regular matter, they both disappear in a flash of light. In the journal Nature, his team reports that they've now used the special laser to probe this antimatter. So far, what they see is that their anti-hydrogen atoms respond to the laser in the same way that regular hydrogen does. That's what the various theories out there would predict -- still, Hangst says, it's important to check. "We're kind of really overjoyed to finally be able to say we have done this," he says. "For us, it's a really big deal." From the journal Nature: "Researchers at CERN, the European particle physics laboratory outside Geneva, trained an ultraviolet laser on antihydrogen, the antimatter counterpart of hydrogen. They measured the frequency of light needed to jolt a positron -- an antielectron -- from its lowest energy level to the next level up, and found no discrepancy with the corresponding energy transition in ordinary hydrogen."

Comments

Re:Well duh.

[BitterOak]

I know your comment was meant to be humorous, but it does raise an important point. There really is no such thing as an anti-laser since lasers produce photons, and photons are their own anti-particle. I.e. there's no such thing as an anti-photon, or to be more precise, a photon and anti-photon are the same thing! That's why an ordinary laser can be used in this experiment.

Test EM Interactions

[Roger W Moore]

Actually it is a bit more specific than that because we already know that matter and anti-matter behave differently under some circumstances. The effect is called 'CP violation" but it only happens for one of the fundamental forces of nature called the weak force which is the one which causes nuclear beta decay.

The atomic spectrum of anti-hydrogen is dependent almost entirely on EM interactions and any slight difference will have a measurable effect on the wavelengths emitted. Hence this gives a very good way to do a high precision test of the EM force for anti-matter to see whether it is at all different.

Corrections

[Roger W Moore]

The C and P symmetries violations in weak interactions is not enough to explain why there is No detectable antimatter in the Universe.

Actually it is the combined CP symmetry which is the important one to test. The C and P symmetries individually are already known to be broken in both weak and EM interactions. For example the different electric charge for anti-matter breaks the C symmetry for EM.

Also the CP violation in the weak force might actually be enough to explain the universe if there is enough of it in the neutrino sector as well and if the neutrino is a majorana particle. These models are called leptogenesis and could explain the observed asymmetry. However that does not mean we should not look for CP violation elsewhere: we know it exists for the weak force, it could easily exist for the strong force but does not seem to (something called the strong CP problem) and so we really should test the EM interactions to see whether there is any effect there which is what this experiment does to a high degree of precision.