# If the radiation emitted by an accelerated electron was sent back to the electron, would the electron decelerate?

Physics Asked by Exocytosis on September 30, 2020

Basically I am asking if photons can be used to change the speed of an electron. Electrons emits electromagnetic radiation when they are accelerated (cyclotron radiation, etc). Can this be reversed? I suspect I might be merely asking if a receiving antenna exists — which obviously does — but I am not sure this is the same.

Electrons and photons are elementary particles and their interaction is described as electron photon scattering by quantum electrodynamis (QED) . As with all interactions input energy-momentum has to be conserved, and there is a probability both for a higher momentum for the electron (acceleration) or higher energy/momentum of the photon. ( quantum mechanical calculations lead to probability distributions)

This is the classical , i.e using Maxwell's equations framework for accelerated charged particles. Classically it is not photons that come out, but electromagnetic radiation. The classical calculation is also correct for an accelerated electron because the classical and QED calculations are consistent with each other. But when one is at the particle frame one uses the energy-momentum four vectors of the particles.

At the QED calculation level it is a part of the electron photon interaction ( virtual photons given by the accelerating electric field) that gives the probability for real photon emission.

Can this be reversed

At the QED level it is reversed, when electrons are accelerated with an electric field, except the photon is a virtual photon provided by the field.

If the radiation emitted by an accelerated electron was sent back to the electron, would the electron decelerate?

So , because the electron emits single photons it is not radiation that can be sent back but a photon that will interact and give a probability for deceleration.

Now in a collective electron beam radiating classical electromagnetic waves, an experiment of sending back that radiation to the beam one would have to calculate the disruption to the beam energy by the individual electron photon scatterings.

Correct answer by anna v on September 30, 2020

## Related Questions

### Transition probability between two harmonic oscillator states (Hemite polynomial integration)

1  Asked on January 8, 2021

### Change of coordinates of Lagrangian

2  Asked on January 7, 2021 by miniplanck

### Using Grassmann variables in describing all the states in the system given by two identical fermions on a circle

0  Asked on January 7, 2021 by brazyoski

### Is brightness proportional to power?

2  Asked on January 7, 2021 by code-noob

### Trouble deriving hydrostatic pressure equation

3  Asked on January 7, 2021 by user142405

### Can observers in different reference frames agree on the time an event took after the fact?

2  Asked on January 7, 2021

### Is there any study about using DMRG to simulate two spin chains coupled at only several sites on each chain?

0  Asked on January 7, 2021

### Can the universe be considered a thermodynamic system?

3  Asked on January 7, 2021

### $I-V$ curve of rf-driven Josephson junctions (Shapiro steps)

0  Asked on January 7, 2021 by olexot

### Question regarding the application of Time Reversal Operator in Expectation Value of Operator in QFT

0  Asked on January 7, 2021

### Holomorphic instantons in target torus

0  Asked on January 7, 2021 by user44895

### Good quantum number for the weak field Zeeman effect

1  Asked on January 7, 2021 by yhmilan

### Beta functions of O$(N)$ model

0  Asked on January 7, 2021

### What is the actual difference between scalar and vector quantities?

1  Asked on January 7, 2021 by sakshi-singh

### What is the interaction between quantum fields and Rovelli’s particulate space of loop quantum gravity?

1  Asked on January 7, 2021

### Hubbard model within mean-field: three different approaches

1  Asked on January 7, 2021 by sr-incerteza

### What is ‘degrees of freedom’ when using Fourier series to express a periodic waveform?

1  Asked on January 7, 2021 by physicsquestion

### Internal resistance problem

4  Asked on January 7, 2021