Particles Live Longer in Accelerators #SpecialRelativity #TimeDilation #Physics #Muon #CosmicRays

Added: 2026-05-19

[00:00:00]A muon. It lives about 2.2 microseconds.

[00:00:04]That's 2.2 millions of a second.

[00:00:08]Muons are created when high-energy cosmic rays strike Earth's upper atmosphere.

[00:00:15]Often more than 6 miles, 10 km above the surface.

[00:00:21]Since nothing can travel faster than light, a muon should decay long before it reaches the ground.

[00:00:29]But many?

[00:00:31]Many of them do reach the ground. In fact, thousands pass through your body every second.

[00:00:39]The reason is special relativity.

[00:00:43]As particles move closer to the speed of light, time itself becomes relative.

[00:00:49]From our perspective, the particle's internal clock, it slows down.

[00:00:56]To the muon, it feels time is completely normal.

[00:01:00]But to us watching from Earth, the muon appears to survive much longer than it should.

[00:01:07]This effect was predicted by Albert Einstein in 1905.

[00:01:14]At more than 99% of the speed of light, the slowing, it becomes dramatic.

[00:01:21]The muon's slowed internal clock allows it to travel miles through the atmosphere before finally decaying.

[00:01:28]Particle accelerators, though, they rely on this constantly.

[00:01:34]Inside CERN and other accelerator facilities, unstable particles are accelerated to enormous speeds. So then scientists have time to study particles that would otherwise vanish almost instantly.

[00:01:51]Relativity also affects GPS satellites.

[00:01:56]Their clocks move differently than clocks on Earth because of speed and gravity.

[00:02:02]Without constant corrections, navigation systems would drift by miles every single day.

[00:02:09]High speed changes the passage of time itself.

[00:02:14]I'm going to repeat that line. It's very important.

[00:02:17]High speed changes the passage of time itself.

[00:02:24]And tiny particles falling from the sky, they prove it continuously.

[00:02:32]These are interesting things with JC.