For the first time, physicists at CERN have observed a benchmark atomic energy transition in anithydrogen, a major step toward cooling and manipulating the basic form of antimatter. Antimatter, annihilated on impact with matter, is notoriously tricky to capture and work with. But its study is key to solving one of the great mysteries of the universe: why anti-matter, which should have existed in equal amounts to matter at the time of the Big Bang, has all but disappeared.
We’re still figuring out what the heck antimatter even is, but scientists are already getting ready to fiddle with it. Physicists at the European Organization for Nuclear Research (CERN) are one step closer to cooling antimatter using lasers, a milestone that could help us crack its many mysteries.
Antimatter is essentially the opposite of “normal” matter. While protons have a positive charge, their antimatter equivalents, antiprotons, have the same mass, but a negative charge. Electrons and their corresponding antiparticle, positrons, have the same mass — the only difference is that they have different charges (negative for electrons, positive for positrons).
When a particle meets its antimatter equivalent, the two annihilate one another, canceling the other out. In theory, the Big Bang should have produced an equal amount of matter and antimatter, in which case, the two would have just annihilated one another.
But that’s not what happened — the universe seems to have way more matter than antimatter. Researchers have no idea why that is, and because antimatter is very difficult to study, they haven’t had much recourse for figuring it out. And that’s why CERN researchers are trying to cool antimatter off, so they can get a better look.
Using a tool called the Antihydrogen Laser Physics Apparatus (ALPHA), the researchers combined antiprotons with positrons to form antihydrogen atoms. Then, they magnetically trapped hundreds of these atoms in a vacuum and zapped them with laser pulses. This caused the antihydrogen atoms to undergo something called the Lyman-alpha transition.
The Lyman-alpha transition is the most basic, important transition in regular hydrogen atoms, and to capture the same phenomenon in antihydrogen opens up a new era in antimatter science.
This phase change is a critical first step toward cooling antihydrogen. Researchers have long used lasers to cool other atoms to make them easier to study. If we can do the same for antimatter atoms, we’ll be better able to study them. Scientists can take more accurate measurements, and they might even be able to solve another long-unsettled mystery: figuring out how antimatter interacts with gravity.
For now, the team plans to continue working toward that goal of cooling antimatter. If they’re successful, they might be able to help unravel mysteries with answers critical to our understanding of the universe.
Nature – Observation of the 1S–2P Lyman-α transition in antihydrogen
UBC – Canadian laser breakthrough has physicists close to cooling down antimatter
Futurism – We’re Almost Able to Cool Antimatter. Here’s Why That’s a Big Deal.