Most Accurate Antimatter Measure Still Can't Explain How Universe Even Exists

Matter—the stuff that makes up everything from tiny ants to massive stars—reigns supreme in the parts of the universe we can see. Its mysterious evil twin, antimatter, barely survived the Big Bang.

To tap into the mystery of how normal matter survived and antimatter perished, scientists have performed the most accurate measurement of the elusive stuff in history. They have revealed its structure in glorious technicolor. Or rather—unprecedented spectral color.

Their research, published in the journal Nature, has stark implications for our fundamental understanding of the universe itself—how it began, and how we came to exist.

Matter-antimatter Asymmetry

In the first moments of the Big Bang, the universe frothed with pairs of matter and antimatter particles, doomed to annihilate each other on contact. Yet, somehow, one in a billion particles of matter survived this massacre, creating everything we see today.

Instead of a universe devoid of all but energy, normal matter makes up nearly five percent of the cosmos.

Antimatter particles, according to prevailing scientific theory, have the same mass as their normal counterparts but the opposite charge. Rather than a negatively charged electron, antimatter atoms have a positively charged twin: the positron.

Finding even the smallest difference between antimatter and matter particles—aside from charge—could help give scientists a clue as to how matter persisted in the universe.

It is very hard for scientists to tease out the mysteries of antimatter because they cannot observe it in nature. Instead, they must create short-lived particles of antimatter in the laboratory.

Hydrogen's Mysterious Twin: Antihydrogen

At the Large Hadron Collider at the European Organization for Nuclear Research, known as CERN, researchers have been testing hydrogen’s antimatter twin: antihydrogen. The LHC smashes particles together at high energy, leaving antiprotons behind. The ALPHA research team used these antiprotons to create antihydrogen. They trapped the antihydrogen with magnets and studied it with light.

“We have measured the spectral line—kind of a color—of the antihydrogen atom with a precision of a few parts per trillion. That’s a factor of a hundred better than we did in the first measurements a year ago,” explained Jeffrey Hangst, ALPHA spokesperson and one of the study authors, in the CERN video above.

The team has honed in on the structure of antihydrogen, revealing, well, that it’s very similar to hydrogen. Both, so far, seem to absorb the same frequency of light.

5_4_Matter in Universe Matter lying between Earth and the edge of the observable universe is shown in this all-sky map from Planck, a European Space Agency mission. JPL-Caltech/ESA/NASA/

Scientists know far more about hydrogen because it is abundant in the universe. As technology and research methods improve, the ALPHA team hope, even more accurate measurements will help them understand the mystery of the “missing” antimatter.

The discovery of any differences, no matter how small, would rock the world of particle physics. This new accurate measurement, however, has found nothing but similarity. More precise measurements, however, are not too far away.

"Although the precision still falls short for that of ordinary hydrogen, the rapid progress made by ALPHA suggests hydrogen-like precision in antihydrogen [measurements]... are now within reach," Hangst added.

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