University of Calgary

Researchers propose new test to learn whether antimatter falls down

UToday HomeMay 2, 2013

Faculty of Science professor Robert Thompson and PhD student Tim Friesen are part of an international collaboration based at CERN, the European Laboratory for Particle Physics near Geneva.Faculty of Science professor Robert Thompson and PhD student Tim Friesen are part of an international collaboration based at CERN, the European Laboratory for Particle Physics near Geneva. Photo by Riley BrandtResearchers in the Department of Physics and Astronomy in the Faculty of Science are among the authors of a study that proposes a new technique to measure the gravitational mass of anti-hydrogen — a technique that may eventually be able to test whether antimatter falls down.

The experimental measurements, published in the prestigious journal Nature Communications, are an important step toward testing the understanding of the behaviour of antimatter and thereby confirming the scientific view of how the universe works.

“Fundamental physics predicts that matter attracts matter gravitationally and that antimatter attracts antimatter gravitationally, and there’s even an extension that says matter and antimatter should attract each other, but that’s never been experimentally confirmed,” says Robert Thompson, who along with grad student Tim Friesen are University of Calgary members of the ALPHA Collaboration, an international collaboration based at CERN (the European Laboratory for Particle Physics).

“What we did was propose a technique to measure the gravitational interaction between the earth’s matter and antimatter,” he says. 

The researchers trapped antihydrogen atoms and then released them. “We are looking for any influence of gravity on the anti-atoms, which enables us to place limits on how strongly anti-hydrogen atoms respond to gravity compared to hydrogen atoms” says Friesen.

While the results of the study are “at least two orders of magnitude away from being scientifically able to answer questions related to gravity and antimatter,” says Thompson, the study is significant because it offers a baseline measurement technique which scientists can now work to refine.

ALPHA has a strong track record of demonstrating proof of principle approaches and then following them until they achieve scientifically significantly results, the researchers say.

“Hundreds of years ago Newton had an apple land on his head and realized that gravity from the earth was attracting the apple to fall on the earth,” he says. “What we’re trying to do is ask the question, is the behavior the same if we drop an anti-apple on earth?”

He says the results are akin to developing the proper procedure for “picking the anti-apple off its tree and dropping it.”

Robert Thompson will be profiled in an interview Saturday, May 4 on CBC’s Quirks and Quarks with Bob McDonald at noon. Online, follow Quirks and Quarks here: http://www.cbc.ca/quirks/

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