Do atmospheric muons accelerate?

[nitsuj]

Cosmic ray muons lose about a third of their energy due to the atmosphere - not exactly insignificant.

Wow, uh yea, the inquiry is more specific than you presume.

 

[Nugatory]

Cosmic ray muons lose about a third of their energy due to the atmosphere - not exactly insignificant.

Although in terms of speed, that's the difference between $.9797c$ and $.9747c$, so assuming constant speed through the atmosphere is still a pretty good approximation.

 

[nitsuj]

Although in terms of speed, that's the difference between $.9797c$ and $.9747c$, so assuming constant speed through the atmosphere is still a pretty good approximation.

Wow does that ever highlight the kinematics with respect to energy required to go just a little bit faster at near c velocities, or in this case the reverse.

 

[Joffan]

Although in terms of speed, that's the difference between $.9797c$ and $.9747c$, so assuming constant speed through the atmosphere is still a pretty good approximation.

Interesting...
... from the Earth's viewpoint, yes... but from the muon's initial frame I would think things look very different. They still experience a massive acceleration from the opposing/onrushing atmosphere. :)

 

[PeterDonis]

from the muon's initial frame I would think things look very different. They still experience a massive acceleration from the opposing/onrushing atmosphere.

They experience proper acceleration (I haven't calculated its magnitude so I don't know if it is aptly described as "massive"), but that only results in a negligible change in the velocity of the Earth in this frame (which will have the same magnitude, but opposite direction, as the the velocity of the muon in the Earth's frame). So it depends on what kind of acceleration you're talking about, proper acceleration (may be significant) or coordinate acceleration (not significant). For purposes of using an inertial frame to model what's going on, the important quantity is coordinate acceleration, which is negligible. For other purposes, proper acceleration might be more important.