UH team helps show how universe survived
By Jan TenBruggencate
Advertiser Science Writer
University of Hawai'i researchers have helped explain why the universe survived its first few moments. They showed that matter and antimatter don't behave the same way.
Physicists believe that the "big bang," the cosmic explosion that is theorized to have created the universe, left equal amounts of matter and antimatter. If matter and antimatter behaved identically, they would have annihilated each other and there would be no matter left to form stars and planets. All that would have remained, said UH Professor Michael Peters, would have been gamma rays, X-rays and light.
A worldwide team of scientists, including members of the UH's High Energy Physics Group, announced their findings at an international physics conference in Rome last month.
The High Energy Physics Group, headed by Stephen Olsen, includes physicists Peters, Tom Browder and Michael Jones; postdoctoral fellow Karim Trabelsi; and graduate students Brendan Casey, Fang Fang, Hulya Guler, Sanjay Swain and Yangheng Zheng. Their research is supported by the U.S. Department of Energy.
The Hawai'i team built and tested some of the equipment used in the experiments, developed software and worked out theory, but the experiments themselves were conducted at the KEK laboratory in Tsukuba, Japan.
There, an accelerator was used to create counter-rotating beams, one of electrons and one of the antimatter version of electrons, called positrons.
The positrons were created by colliding electrons, traveling at near the speed of light, into ordinary matter, Peters said. The positrons would normally destroy themselves by interacting with electrons. Researchers prevented that by controlling them with powerful magnetic and electrical fields in a very high vacuum.
Once the positrons and electrons were both rotating in the accelerator at extremely high speed, they were collided into each other. Physicists then observed the decay of the resulting particles.
Their finding: Matter and antimatter decay in different ways. They do not behave symmetrically.
Earlier this summer, researchers at the Stanford Linear Accelerator Center in California had shown similar asymmetrical behavior, but found a lower level of difference between the two kinds of matter.
The findings help explain why — despite equal amounts of matter and antimatter having existed at the instant of the "big bang" — there are now different amounts. The difference in the way they decay, along with other factors, would help explain why there is today far more matter than antimatter in the universe, Peters said.
Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.
