High-energy subatomic particles coming from space interact with atoms in the earth’s upper atmosphere, in some cases producing unstable particles called muons. A muon decays into other particles with a mean lifetime of 2.20 ms = 2.20 x 10-6 s as measured in a reference frame in which it is at rest. If a muon is moving at 0.990c relative to the earth, what will an observer on earth measure its mean lifetime to be?

High-energy subatomic particles coming from space interact with atoms in the earth’s upper atmosphere, in some cases producing unstable particles called muons. A muon decays into other particles with a mean lifetime of 2.20 ms = 2.20 x 10-6 s as measured in a reference frame in which it is at rest. If a muon is moving at 0.990c relative to the earth, what will an observer on earth measure its mean lifetime to be?