In a test of Einstein’s theory of special relatively, physicists at CERN have just reported the first ever measurement of the light emitted by an antimatter atom—revealing that antihydrogen is the exact mirror image of regular hydrogen. The result confirms what has already been predicted by the law of physics and could help us solve one of science’s biggest mysteries: why is there so much more regular matter in the Universe than antimatter?
The law of physics predicts that for every particle of regular matter, there’s an antiparticle. That means for every regular hydrogen atom, there’s an antihydrogen atom. Just as the hydrogen atom is made up of an electron bound to a proton, the antihydrogen atom is made up of an antielectron bound to an antiproton.
“This represents a historic point in the decades-long efforts to create antimatter and compare its properties to those of matter,” Alana Kostelecky, a theoretical physicist from Indiana University told NPR.
It’s believed that if an antiparticle finds a regular particle, they will cancel each other out—releasing energy in the form of light. This creates multiple problems. It makes it virtually impossible for physicists to find antimatter in nature because it will likely be annihilated by regular matter before they get the chance to start looking. Secondly, if our current physics models suggest than an equal amount of regular particles and antiparticles were produced by the Big Bang, the theory suggests everything in the Universe would have canceled itself out.
“Something happened, some small asymmetry that led some of the matter to survive, and we simply have no good idea that explains that right now,” Jeffrey Hangst, part of the team from the ALPHA experiment at CERN commented in a press statement.
With scientists able to measure the kind of light given off by antihydrogen atom when hit by a laser and able to compare that with the light given off by a hydrogen atom—our understanding could change entirely. This discovery is small but mighty—marking the first time we’ve been able to control an antiparticle long enough to measure its behavior.
“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,” Hangst continued.
Because this observation is impossible to make in nature, scientists have had to produce their own anti-hydrogen atoms. Over the past two decades, the ALPHA team has been trying to produce enough of these antihydrogen atoms to work with them—and have landed on a successful technique that allows them to create about 25,000 antihydrogen atoms every 15 minutes. Of those tens of thousands, they can trap 14 of them. Previous methods could only ever trap 1.2.
By using the laser, the team found that the antihydrogen atom emitted the exact same light spectrum as a regular hydrogen atom put through the same test. The result is consistent with the Standard Model of particle physics.
“It’s long been thought that antimatter is an exact reflection of matter, and we are gathering evidence to show that is indeed true,” Tim Tharp from ALPHA told Gizmodo.
Now, physicists have the chance to test more spectra emissions using different types of lasers. If they all end up identical, Einstein’s special relativity will survive the test.
If matter and antimatter don’t mirror each other, it would change the way we think about spacetime, the laws of physics, and our models of the Big Bang theory.
Sources: ScienceAlert, Nature, NPR