Australian scientists have observed how earth stops high-energy neutrino particles in their tracks for the first time.
The international study, led by University of Adelaide scientists, marked the first time that the earth's absorption of neutrinos has been observed.
Because neutrinos are so small and have no discernable charge they are able to pass through a vast majority of matter unimpeded and undetected.
However, scientists showed for the first time that earth can stop neutrinos with energy much higher than can be produced or tested synthetically, as predicted by the Standard Model of Particle Physics which explains the fundamental physics of the universe.
The observations were made at the IceCube Neutrino Observatory, a detector consisting of 5,000 basketball-sized sensors buried deep below Antarctic ice at the South Pole.
The optical sensors measure flashes of blue light which are emitted when neutrinos interact with the ice.
Scientists were able to examine the rate at which neutrinos were arriving at the site from all directions.
They determined that while most neutrinos pass through the earth uninhibited, those that collided with either protons or neutrons were absorbed, ending their otherwise uninhibited journey through the galaxy.
Gary Hill, an associate professor at the University of Adelaide, said the findings will increase the understanding of particle physics.
"The Standard Model of Particle Physics works really well to predict everything we've measured in particle accelerators on Earth," Hill said in a media release on Thursday.
"However, those accelerators only make neutrinos up to energies about 1,000 times smaller than the most energetic that IceCube sees.
"We can never build an accelerator to make neutrinos with enough energy to directly test these predictions. Fortunately, cosmic rays come to Earth at much higher energies and make neutrinos in the atmosphere at extreme energies."
