Pair awarded Nobel physics prize for solving elusive particle puzzle

A Japanese and a Canadian scientist were awarded the 2015 Nobel Prize for Physics on Tuesday for discovering that elusive subatomic particles called neutrinos have mass, opening a new window onto the fundamental nature of the universe.

Neutrinos are the second most bountiful particles after photons, the particles of light, with trillions of them streaming through our bodies every second, but their true nature has been poorly understood.

Takaaki Kajita’s and Arthur McDonald's breakthrough was the discovery of a phenomenon called neutrino oscillation that has upended scientific thinking and promises to change understanding about the history and future fate of the cosmos.

Professor Barbro Asman says the discovery will fundamentally change the scorebooks in physics and could help explain human existence and the origin of the universe.

Asman, a member of the Royal Swedish Academy of Sciences, compared Kajita's and McDonald's discovery that the neutrino particles can change identities to the groundbreaking discovery of the Higgs particle.

"This is a really big discovery" that "opens up a new window in physics,” she said.

Asman said the discovery could help explain why there is more matter than antimatter in the universe, a riddle that has eluded scientists for years.

"When matter is created, it's created with equal amount of matter and antimatter," she says. "So the problem we have then is why are we here containing only matter?

In awarding the prize, the Royal Swedish Academy of Sciences said the finding had “changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.”

For many years, the central enigma with neutrinos was that up to two-thirds fewer of them were detected on Earth than expected.

Kajita and McDonald, using different experiments, managed to explain this around the turn of the millennium by showing that neutrinos actually changed identities, or “flavors,” and therefore must have some mass, however small.

McDonald told a news conference in Stockholm by telephone that this not only gave scientists a more complete understanding of the world at a fundamental level but could also shed light on the science behind fusion power, which drives the sun and could one day be tapped as a source of electricity on Earth.

"Yes, there certainly was a Eureka moment in this experiment when we were able to see that neutrinos appeared to change from one type to the other in traveling from the sun to the Earth," he said.

Kajita is director of the Institute for Cosmic Ray Research and professor at University of Tokyo, while McDonald is professor Emeritus at Queen's University in Canada.

The $962,000 physics prize is the second of this year's Nobels. Previous winners of the physics prize have included Albert Einstein, Niels Bohr and Marie Curie.

The prizes were first awarded in 1901 to honor achievements in science, literature and peace in accordance with the will of dynamite inventor and business tycoon Alfred Nobel.

The prize for medicine was awarded on Monday to three scientists for their work in developing drugs to fight parasitic diseases including malaria and elephantiasis. 

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