Although many experiments have been cited as empirical verification of special relativity, they are not experiments that could not have questions raised about their validity as proofs. There is one simple experiment that could be carried out to put to rest, incontrovertibly, the controversies concerning the validity of special relativity - by a direct measurement of the speed of beta particles from beta decay. If special relativity is correct, no electrons would be found to go faster than light speed. If special relativity is invalid, then kinetic energy obeys the old 1 / 2 mv2 formula. Some beta particles could be ejected with kinetic energy greater than 1 MeV; such electrons would be detected to travel at about twice the speed of light. Though it is one of the simplest experiment that many laboratories over the world could perform,until now, the experiment has yet to be carried out.