There is a dust layer in the ice at the South Pole about 2km under the surface that interferes with about 5000 photomultiplier tubes spread out over a cubic kilometer in the ice that are watching for light created from high energy muons moving faster than the speed of light in the ice that were in turn the result of the very rare chance of a high energy neutrino interacting with the nucleus of a single atom in the ice.
There is a dust layer in the ice at the South Pole about 2km under the surface that interferes with about 5000 photomultiplier tubes spread out over a cubic kilometer in the ice that are watching for light created from high energy muons moving faster than the speed of light in the ice that were in turn the result of the very rare chance of a high energy neutrino interacting with the nucleus of a single atom in the ice.