A team of CERN researchers announced on Wednesday that they have demonstrated for the first time that antimatter interacts with gravity in the same way as matter, an experiment that once again confirms Albert Einstein’s theory of general relativity, Reuters reports.

Everything that surrounds us in the universe – planets, stars, poodles and lollipops – is made of ordinary matter. Antimatter is its mysterious “double”, which has the same mass but the opposite electrical charge.

Almost all subatomic particles, such as electrons or protons, have an antimatter counterpart. While electrons have a negative charge, antielectrons, also called positrons, are positively charged.

Similarly, while protons have a positive charge, antiprotons are negatively charged.

In the modern cosmological paradigm, the Big Bang explosion that gave birth to the universe as we know it should have created equal amounts of matter and antimatter.

But the reality looks different: antimatter is very little and almost zero on Earth.

Also, matter and antimatter are “incompatible,” exploding violently when they collide in a phenomenon physicists call “annihilation.”

What CERN’s new antimatter experiment predicts

The new antimatter experiment was conducted at the European Center for Nuclear Research (CERN) in Switzerland as part of an international joint project called the Antihydrogen Laser Physics Apparatus (ALPHA).

The experiment involved the use of antihydrogen, the antimatter version of the lightest element in the universe.

“On Earth, most naturally occurring antimatter is produced by cosmic rays — energetic particles from space — colliding with atoms in the air and creating antimatter-matter pairs,” says physicist Jonathan Wurtele of the University of California, Berkeley, and co-author of the new study, published in the journal Nature.

This newly created antimatter exists only until it collides with an atom of normal matter in the lower atmosphere.

But antimatter can be artificially produced under controlled conditions, such as in the ALPHA experiment, a team of researchers uses antihydrogen, created at CERN, as its basis.

The anti-hydrogen was stored under vacuum in a special cylindrical chamber and “locked” with the help of magnetic fields located at the top and bottom.

The researchers then reduced the magnetic fields to “release” the antimatter, and watched how it behaved when the effects of gravity became apparent. Simply put, scientists wanted to see if antihydrogen would fall to Earth like normal matter.

It behaved exactly the same as hydrogen under those conditions.

A contradiction of Einstein’s theory would be a “big surprise”

“This result was predicted in theory and indirect experiments based on subtle phenomena. But no one has ever done a direct experiment where antimatter is just left to see where it falls,” said Joel Fians, another physicist at Berkeley and co-author of the study.

“Our experiment rules out other theories that require the rise of antimatter in the Earth’s gravitational field,” Wurtele also explained.

Although Albert Einstein formulated his famous theory of relativity before the discovery of antimatter in 1932, he viewed all matter as equivalent. In other words, according to his theory, antimatter should behave like matter when it is subjected to the interaction of gravity.

But what if antimatter lived up to expectations?

“It would be a huge surprise because it would be a significant contradiction to many theories,” says William Bertsche, another physicist and co-author of the study, this time from the University of Manchester.

“I think it shows the validity of general relativity and the principles that follow from it,” he added.

The great mystery of antimatter still remains unsolved

As for the extreme rarity of antimatter in the observable universe, it remains a mystery.

For example, there is no indication that there are galaxies that are made entirely of antimatter, as is the case with normal matter.

“The near complete absence of naturally occurring antimatter is one of the big questions facing physics,” says Wurtele.

An experiment currently underway at CERN, however, rules out one of the hypotheses for the rarity of antimatter – that it was gravitationally pushed away by matter during the Big Bang.

“No matter how beautiful the theory, physics is a science based on experiments,” emphasizes Fiennes.