NEW YORK (Reuters) - U.S. and Japanese scientists said Thursday they have evidence that tiny sub-atomic particles called neutrinos have mass, a finding that could be key to establishing the Grand Unification theory of physics.
Physicists said that if the finding is confirmed by future experiments, it will cause a revision of the so-called Standard Model that describes interactions of elementary particle physics. In the Standard Model, neutrinos have no mass.
"These new results could prove to be the key to finding the Holy Grail of physics, the unified theory," said John Learned, University of Hawaii Professor of Physics and Astronomy and one of the authors a paper on a neutrinos experiment in Japan.
"Neutrinos cannot now be neglected in the bookkeeping of the mass of the Universe."
The unified theory of physics, also called the Grand Unification, is what scientists would like to see: A combination of what is known as strong interaction, weak interaction and electromagnetism theory in a single framework.
Grand Unification is a step removed however from the great quest of 20th century physics -- coming up with the so-called "theory of everything" in our Universe that would also describe gravitational force.
Known to physicists as the "Superstring theory" it would explain everything from what it was like in the milliseconds immediately after the Big Bang to what keeps people and objects rooted to Earth.
The Big Bang is the hypothesized explosive birth of the Universe, a theory that is widely accepted to explain the origin of the Universe in one explosive moment. The theory has been challenged by scientists and non-scientists alike.
The latest finding, to be presented in a paper Friday at a conference of physics and astrophysics in Takayama, Japan, caused excitement in the international physicist community. "It's a really incredibly exciting moment because of all of the particles we know neutrinos are among the most mysterious," said Professor Chang Kee Jung of SUNY Stony Brook in New York, one of the universities that took part in the experiment.
He said neutrinos are tiny particles that float around without much interaction. About 500 billion neutrinos can pass by a person's fingertip every second. Neutrinos were discovered four decades ago and have been the subject of intense experimental and theoretical research.
An experiment deep inside a Japanese mine has yielded results that are outside the Standard Model theory of elementary particle physics, which describes the fundamental constituents of matter and their interactions.
"So far the Standard Model works really well, we can explain just about everything we see but we know there has got to be something more out there," said Dr. Evalyn Gates, a research scientist at the University of Chicago who was not involved in the project.
"Knowing that neutrinos do have mass begins to direct some of these models. It would be the first definite evidence of new physics and that's why everyone is excited about this."
The paper presented Friday in Japan has been sent to the leading physics journal, "Physical Review Letters." It describes results from the first two years of data collected from a $100 million experiment called Super-Kamiokande.
The experiment uses a 12.5-million gallon stainless steel-lined tank of highly-purified water located about 3,300 feet underground in a Japanese mine. Faint flashes of light given off by the neutrino interactions in the tank were observed by 13,000 lights. The collaboration is led by University of Tokyo's Institute for Cosmic Ray Research and includes six U.S. universities and eight from Japan.