A story of muons

mu-mesons (muons) are a type of particles which disintegrate spontaneously after an average lifetime of 2.2 × 10^-6 sec.

It is clear that in it's short lifetime a muon cannot travel more than 600 meters even at the speed of light. But even though muons are created at top of the atmosphere around 10 kilometres above from where they are actually detected in the laboratories.

How can that be possible? The answer is various muons move at various speeds from their point of view the muons live only for 2 micro sec but in our point of view they live longer, enough longer to reach the earth.

The time runs slower for the objects moving with larger speeds.

Even though we don't know why they disintegrate, with the help of this experiment by finding average apparent lifetime of these particles at various speeds we are able to determine their speeds precisely using Lorentz equations.

And answer is yet again Einstein's Special theory of relativity.