Neutrino: a near-mass-less, fundamental particle with no electrical charge that travels at or close to the speed of light, sometimes referred to as the ‘ghost particle.’  To date, three types of neutrino have been discovered: electron-neutrinos,  muon-neutrinos, and tau-neutrinos. Each variation of neutrino is named respective to it’s electrically charged particle counterpart (electron, muon, and tau). For each variation of Neutrino, there is also a corresponding antineutrino which identically has no electrical charge and possesses a half-integer spin, but can be differentiated by its opposite signs of lepton number and chirality. The Neutrino was first hypothesized in 1931 by physicist Wolfgang Pauli as a means of resolving an apparent energy and momentum loss that had been observed in a number of radioactive decay scenarios. Pauli suspected that the energy was being transported away by an undetected neutral particle. It was not until nearly forty years had passed, in 1968, that the particle was first successfully identified. Neutrinos are some of the strangest and most elusive sub-atomic particles in the known universe and are capable of passing through virtually all forms of matter.