When a charged particle is moving with large kinetic energy in the Earth's reference frame, can it emit a photon effectively slowing it down in this frame?
1 Answer
It is not enough for it to be moving - it needs to accelerate (or decelerate). An accelerating charged particle will emit radiation and it will lose energy as a result.
An excellent example would be the loss of energy of charged particle in synchrotron accelerators. They emit... synchrotron radiation. This is either a boon (e.g. the Diamond light facility that generates synchrotron radiation beams for use in various experiments), or a problem in particle accelerators, where some means of replenishing the lost energy must be incorporated into the design.
For example here you can find a discussion of how the design (including its radius) of the Large Electron-Positron collider was influenced by the consideration of synchrotron radiation losses.
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$\begingroup$ It is also not necessary for it to be moving at all. Some of the energy lost by the agency causing the acceleration goes into radiation (and into Schott fields) instead of into mechanical momentum. After all, motion is relative. And if the agency is gaining energy then it gains less than what the charge loses with the remainder going into Schott fields and radiation fields. $\endgroup$– TimaeusCommented Aug 5, 2015 at 22:43