Electric field and light and stuff

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Discussion Overview

The discussion explores the effects of strong electric fields on light beams, particularly in the context of laser beams passing through parallel plate capacitors and nonuniform electric fields, such as those produced by large metallic spheres at high electric potentials. The conversation touches on both classical and quantum mechanical perspectives.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether a light beam is affected by a strong electric field, particularly in steady versus alternating fields.
  • One participant suggests that Maxwell's equations being linear implies no effect on light in a steady electric field, except possibly in nonlinear media.
  • Another participant proposes that while there may be no effect in a steady field, there could be a very small effect during the buildup of an electric field or in alternating fields.
  • A contribution mentions that quantum mechanics predicts the possibility of particle creation from light quanta in strong electric fields, although other conditions are necessary for this to occur.
  • One participant emphasizes that their previous comments were made in a classical context, acknowledging the quantum perspective introduced by others.
  • Another point raised is the potential gravitational bending of light beams near regions of high electric field energy density, which is attributed to the energy density rather than the electric field itself.
  • Participants discuss the gravitational interaction of electromagnetic fields, noting that both light beams and electric fields carry energy, which can influence their interaction.
  • A participant introduces the Faraday effect, suggesting that light traveling through a medium is affected by magnetic fields and presumes a similar effect may occur with electric fields.

Areas of Agreement / Disagreement

Participants express differing views on the effects of electric fields on light, with some arguing for classical explanations and others introducing quantum mechanical considerations. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

Participants acknowledge the need for additional conditions for certain effects, such as particle creation, and the limitations of classical versus quantum mechanical frameworks in explaining the interactions involved.

crx
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Is there any effect on a light beam in a strong electric field? I'm thinking to a laser beam that passes trough a very long parallel plate capacitor. And what if we have an nonuniform, electric field, like in the case of a very large metallic sphere at a high electric potential? Thanks!
 
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Maxwell's equations are linear, so I don't think there would be an effect. The only way I could see there being an effect would be in the presence of a nonlinear medium instead of free space.
 
crx said:
Is there any effect on a light beam in a strong electric field? I'm thinking to a laser beam that passes trough a very long parallel plate capacitor. And what if we have an nonuniform, electric field, like in the case of a very large metallic sphere at a high electric potential? Thanks!

I would have thought that there would be no effect in a steady electric field but there might be a very very small effect during the build up of an electric field or an alternating electric field.
 
Quantum mechanics predicts that in a strong enough electric field, two light quanta of sufficient energy can turn into an electron and a positron. Actual real particles with mass, fermionic spin, charge and all.

Someone will no doubt point out that other conditions are needed, but the equations indicate that the probability of particle creation depends on the electric field strength.
 
That is a good point. I should emphasize that I was speaking in strictly classical terms.
 
If the field is Very strong, one could also add the effect of gravitational bending of the beam passing close to the region of higher field, but it would be due to the field's high energy density and not to the fact that it's an electric field.
 
Electromagnetic fields are not self interacting, per Dalespams post #2.

As lightarrow points out, there is a small gravitational interaction since the electromagnetic fields (the light beam and the electromagnetic field) both carry energy. (energy is a component of the Einstein stress/energy/momentum tensor.)

Another way to think of the answer:all radiation is affected by gravity...following the above logic.
 
sorry but have any of you heard of the Faraday effect?

light traveling through a medium IS effected by magnetic field and I presume, similarly an electric field.

http://en.wikipedia.org/wiki/Faraday_effect

right?
 

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