As a cosmic ray encounters the upper atmosphere, an elementary particle called a muon is generated, which shoots down to Earth's surface at almost the speed of light. The half-life for a muon is 1.5 μs. A detector set out on the top of a mountain detects a steady flux of muons. Another detector at sea level detects far more muons than expected, based upon the half-life and the distance between altitudes of the detectors. Which of the following could be the cause of this discrepancy?
Answer Choices,
The altitude measurements were not accurate.
The half-life measurement for the muon was incorrect.
Time was moving more quickly for the muon, so not as many decayed.
Time was moving more slowly for the muon, so not as many decayed.