spaceSpace and Physics

Light Spectrum Of Antimatter Observed For The First Time, And It Looks Like Regular Matter


Jonathan O'Callaghan

Senior Staff Writer

The ALPHA experiment. Maximilien Brice/CERN

Ever wondered what antimatter looks like? Well, wonder no more, as scientists have managed to get a glimpse of it in optical light for the first time – and, well, it looks a lot like regular matter.

The research took place at the ALPHA experiment inside CERN, the goal of which has been to look at the similarities and differences between matter and antimatter. The research was published in the journal Nature.


In this experiment, scientists used a laser to measure antihydrogen, the antimatter counterpart to hydrogen. Antimatter is notoriously hard to study because, by its nature, it is destroyed in the blink of an eye, so a sophisticated magnetic trap was used to make it possible.

“Using a laser to observe a transition in antihydrogen and comparing it to hydrogen to see if they obey the same laws of physics has always been a key goal of antimatter research,” said Jeffrey Hangst, spokesperson of the ALPHA collaboration, in a statement.

CERN said this experiment was the first time the light spectrum of matter and antimatter had ever been compared. Interestingly, both hydrogen and antihydrogen were found to have identical light spectrums – a prediction made by the Standard Model of particle physics. The difference between them, though, is that hydrogen is made of an electron and a proton, while antihydrogen is made of a positron and antiproton.

To make antihydrogen for the experiment, scientists mixed a plasma of about 90,000 antiprotons with positrons, producing 25,000 antihydrogen atoms per attempt. About 14 of these could be trapped in the experiment, and by shining them with a laser beam at a precise frequency, the interaction of the beam and the antihydrogen could be measured.


“Moving and trapping antiprotons or positrons is easy because they are charged particles,” added Hangst. “But when you combine the two you get neutral antihydrogen, which is far more difficult to trap, so we have designed a very special magnetic trap that relies on the fact that antihydrogen is a little bit magnetic.”

Now, the scientists are hoping to making finer measurements of antimatter, in the hope of solving one of the universe’s biggest mysteries – namely, why matter far outweighs that amount of antimatter in the universe, despite both being thought to have been created in equal amounts in the Big Bang.


spaceSpace and Physics
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