LabscopesandThe Universe

Why (Anti)hydrogen Matters

By Jonathan Liu

May 5, 2017

For the first time, scientists have been able to trap and study antimatter. Antimatter consists of particles that have the same mass, but opposite electric charge, as ordinary matter. Although theoretical physicists have investigated it for decades, antimatter is nearly impossible to study experimentally because it explodes upon contact with normal matter. Physicists have developed theories for how antimatter should behave, but no scientists have experimentally confirmed their predictions—until now.

Researchers at CERN, the European particle physics laboratory, recently developed a technique to produce and trap antihydrogen—an atom just like hydrogen but composed of antimatter instead. Through a technical tour de force, the research team, known as the ALPHA scientists, created a sophisticated magnetic trap to confine antihydrogen and sequester it from matter. This technique allowed researchers to prevent antihydrogen’s destruction for long enough to study it under controlled circumstances.

“This is a huge leap forward for the field,” says Joel Fajans, a principal investigator in the ALPHA collaboration and professor of physics at UC Berkeley. “People have been trying to study antihydrogen since the 1980s. It wasn’t until now that we achieved the technological breakthroughs necessary to do so.”

Using the trap, researchers measured how antihydrogen absorbs light. The prevailing models indicate that antihydrogen should absorb light exactly like hydrogen, so even a tiny deviation from antihydrogen’s anticipated behavior would challenge the foundations of modern physics.

So far, the researchers have found no discrepancy between antihydrogen’s actual and predicted behaviors. Now that the technology is in place, researchers plan to explore this new field of experimental science further to better investigate fundamental predictions of physics.

Featured image: Hydrogen (above) and anti-hydrogen (below). Designed by Cameron Baker.

Jonathan Liu is a first year graduate student in physics studying the biophysics of fruit fly development. In his free time he sings with the UC Berkeley Chamber Chorus and likes to dance West Coast Swing.

This article is part of the Spring 2017 issue.

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