Time dilation : an experiment with mu-mesons

Presents by experimental means the dilation of time by using the radioactive decay of cosmic ray mu-mesons. The experiment shows how data are taken from the decay of mu-mesons at rest, mu-mesons which arrive on top of Mt. Washington, and the number that survive to reach sea level. From the results of these time distribution measures the conclusion is drawn that the mesons keep time at about one-ninth the rate they do when they are at rest.