PHYSICISTS have made a key measurement of anti-atoms, and found that they look just like atoms.
The result means we are no closer to solving the mystery of why we live in a universe made only of matter, or why there is anything at all.
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Antimatter particles are the same as matter particles, but have the opposite electrical charge. If the two meet, they annihilate in a blitz of light and energy.
The problem is that the standard model, physicists鈥� well-tested theory of particles and their interactions, predicts that matter and antimatter were created in equal quantities in the big bang, so both should have disappeared in an orgy of annihilation shortly after.
This has led to the suggestion that there is a small imbalance between matter and antimatter properties, which allowed some matter to survive and form the universe of stars and galaxies we live in. But we have failed to find much evidence of one.
Now the ALPHA collaboration at the CERN particle physics lab near Geneva, Switzerland, has measured a property known as the Lamb shift, which is caused by fluctuations in the quantum vacuum thought to pervade all of space, in atoms of antihydrogen.
These consist of a positively charged electron, or positron, circling an antiproton. Just as the standard model predicts, the Lamb shift was the same in atoms of hydrogen and antihydrogen.
鈥淎n imbalance between matter and antimatter may have allowed some matter to survive the big bang鈥�
It is too early to conclude that the Lamb shift can鈥檛 help to explain the antimatter mystery, however. The measurements are consistent only to within one decimal place, so it is possible that future research will discover subtle differences between the Lamb shift of atoms and anti-atoms (, DOI: 10.1038/s41586-020-2006-5).
鈥淭his measurement is certainly an important step forward,鈥� says Chlo茅 Malbrunot, who works on the rival ASACUSA experiment, also at CERN.
