Neutrinos are elementary subatomic particles with no electrical charge and very little mass. They are affected only by the weak subatomic force, and consequently shoot through matter without striking another particle. Some physicists have claimed a neutrino of moderate energy could penetrate a block of lead a thousand light years long.
The neutrino was first proposed in 1930 to explain the beta decay of a neutron. The energy of a neutron before decaying into an electron and proton was greater than the aggregate electron and proton produced by the beta decay reaction. The neutrino particle was theorized to preserve energy, momentum, and angular momentum.
In my blog, Did CERN Scientists Discover an "Undo" Button?, I explain that European scientists are puzzled because speed tests of neutrinos resulted in speeds faster than light. As you have been taught, Albert Einstein's Theory of Relativity states no particle can travel faster than light. A century ago, Michelson and Morely measured the speed of light in the direction of the Earth's spin and against the Earth's spin. They measured the speed of light the same in both directions.
In other words, suppose you are on a rocket sled and shine a flashlight. The photons leaving the flashlight cannot travel faster than the speed of light, even though intuitively the photons should travel at the speed of light plus the speed of the rocket sled. But they don't, which is one of the strange features of relativity.
Faster-than-light neutrino experiment to be run again explains the scientists published their findings in hope that someone could identify an error. Over 80 papers have been submitted to CERN in response, but most propose new theories rather than identifying experimental error. One of the problems confronting researchers is that they cannot produce a single neutrio and measure how long it took to travel from the CERN Geneva laboratory to the Gran Sasso laboratory in Italy. They can only produce a burst of neutrinos and measure the average time of travel. In the new experiment, they will generate shorter bursts of neutrinos and calculate whether that makes a difference.
The universe is very bizarre if neutrinos can travel faster than light.