Why does anything exist? Scientists find a bit of the answer
Scientists probing the nature of antimatter have found a bit more evidence to explain why the universe is not an empty husk, although not enough to account for the billions of galaxies strewn across the cosmos.
Physicists believe that equal amounts of matter and antimatter were created in the Big Bang at the birth of the universe 13.8 billion years ago. Within one second, however, the antimatter had all but disappeared.
That vanishing act - leaving us in a universe with a surplus of matter forming the stars, the Earth and all known life - must be due to a subtle difference between matter and antimatter.
Researchers said they had found tiny variations in the way a type of particle decayed into matter and antimatter during collisions in the Large Hadron Collider (LHC), the giant particle-smasher buried 100 meters (330 feet) underground at the foot of the Jura mountains outside Geneva.
The latest findings are the first to show that a particle known as a Bs meson has a slight preference for decaying into matter and are consistent with earlier experiments on other particles. Unfortunately, the differences are still far too small to explain the great abundance of matter around us.
"The difference that we see in the behavior of antimatter and matter only adds up to about a galaxy's worth, not half a universe," Tara Shears of the University of Liverpool, one of the physicists working on the experiment, said in an interview.
The results, which have been submitted for publication in the journal Physical Review Letters, fit with the three-decade old Standard Model, which aims to describe everything known about how fundamental particles behave.
"Everything seems to add up, it is just that it doesn't come to anything near the amount of difference we need to explain the evolution of the universe," Shears said.
The CERN scientists made their new discovery after analysing data from 70 trillion collisions between protons in one of four main experiments at the LHC.
They still have another particle to study in this experiment, but they are also ready to cast their net wider to explain the puzzling predominance of matter over antimatter.
"By studying these ... effects, we are looking for the missing pieces of the puzzle," said Pierluigi Campana, another scientist on the collaboration.
Matter and antimatter are almost identical, with the same mass but opposite electrical charges. They can form separate parts of some elementary particles but if they are mixed together both are destroyed instantaneously.
The first observation that particles can decay unevenly into matter and antimatter won two scientists at Brookhaven Laboratory in New York a Nobel Prize in 1980.
After discovering a long-sought elementary particle called the Higgs boson last summer, the giant collider run by CERN, the European Organisation for Nuclear Research, is currently being upgraded to nearly double its power by 2015.
Scientists hope the extra power will open up an entirely new realm of physics to help explain the antimatter conundrum, as well as other mysteries such as dark matter, the unseen stuff that helps to glue galaxies together.