Stockholm – Takaaki Kajita of Japan and Arthur McDonald of Canada have won the Nobel Prize in Physics for discovering that tiny cosmic particles, which pass easily through Earth and human bodies, known as neutrinos, have mass. They whizz trough space at nearly the speed of light. Finding that they possess mass, which people commonly understand as weight, is a key discovery in science.
Kajita, 56, is director of the Institute for Cosmic Ray Research and professor at the University of Tokyo. McDonald, 72, is a professor emeritus at Queen’s University in Kingston, Ontario. Both worked together to dispel a long-held notion in the world of science that believed neutrinos had no mass.
“The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe,” the Royal Swedish Academy of Sciences said in awarding the prize.
McDonald told reporters in Stockholm by phone that the discovery helped scientists fit neutrinos into theories of fundamental physics. Kajita reminded in a news conference at his university that the findings were a contribution of many people. “The universe where we live is still full of unknowns,” he said. “A major discovery cannot be achieved in a day or two. It takes a lot of people and a long time.”
The discovery
Neutrinos are subatomic particles produced by the decay of radioactive elements. They are also elementary particles that lack electricity charge. Frederick Reines, 1995 Nobel Prize for his co-detection of the neutrino, described them as “… the tiniest quantity of reality ever imagined by a human being”. Trillions of them pass through the human body every second according to scientists.
These particles come in three types or “flavors”: electron, muon and tau. Kajita and McDonald showed that neutrinos have actually the ability to spontaneously shift between types, a process called neutrino oscillation. This, in turn, means they have mass.
In 1988, Kajita showed that neutrinos created in Earth’s atmosphere and captured at the Super-Kamiokande detector in Japan had changed flavors. Then, after three years, McDonald found that neutrinos coming from the sun also switched identities.
The answer to the question about the weight of this particles is still unknown. Guido Drexlin, a neutrino expert at the Karlsruhe Institute of Technology in Germany will work with his team to determine the weight of these particles. “Neutrinos are a million times lighter than an electron, which is a charged version of a neutrino,” said Drexlin, according to The New York Times.
The Physic world is excited
These discoveries have important implications. For instance, they could help scientists understand the matter-antimatter puzzle. Scientists believe that during the Big Bang, equal amounts of matter and antimatter were produced. The smash-ups with matter destroyed most of the anti-matter, leaving a slight excess of matter in the universe.
It is not known why the matter won the battle, but one way to start investigating the reason is by looking for the differences between matter and anti-matter. Flavor-changing neutrinos could be one of these differences.
Robert G.W. Brown, chief executive officer of the American Institute of Physics said at the Nobel Prize event that these findings “change our understanding of the fundamentals of particle physics, and particles make up everything in the universe.”
On the other side, Antonio Ereditato, director of the Albert Einstein Center for Fundamental Physics at the University of Bern, Switzerland, congratulated the award saying, “This is really one of the milestones in our understanding of nature.”
“[The findings] really inspired a whole global community of scientists to drop what they were doing and try to understand the neutrino,” said Joseph Lykken, deputy director of the Fermi National Accelerator Laboratory in Batavia, Illinois.
On Monday, the Nobel Prize in medicine went to scientists from Japan, the U.S. and China for doscovering drugs that are now used to fight malaria and other tropical diseases. On Wednesday, the Nobel chemistry Prize will be announced, followed by literature on Thursday and economics next Monday.
Source: The New York Times