If light has no charge and mass, how can it have an electric field?

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Discussion Overview

The discussion revolves around the nature of light, specifically photons, and their relationship with electric and magnetic fields. Participants explore whether photons can exist independently of an electromagnetic field and how test charges behave in the presence of light. The conversation includes theoretical considerations and references to experimental observations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that a photon does not produce an electric field, as it is a neutral particle and an excitation of the electric field.
  • Others argue that a test charge placed near a photon would move in alternating directions, suggesting a dynamic interaction with the electric field.
  • Several participants express interest in experimental evidence or videos demonstrating the behavior of test charges in relation to light.
  • One participant questions whether a photon can exist without an external electromagnetic field, suggesting that the electric and magnetic fields balance when traveling at the speed of light.
  • Another participant asserts that a photon cannot exist without the electromagnetic field, indicating that it is the quanta of interaction with that field.
  • There is a question about whether a photon creates its own electromagnetic field as it travels or if the field is pre-existing.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between photons and electromagnetic fields, with no consensus reached on whether photons can exist independently of these fields or how they interact with test charges.

Contextual Notes

Participants reference various experimental observations and suggest that the behavior of test charges in relation to light may not be straightforward, indicating a need for further exploration of the underlying principles.

Who May Find This Useful

This discussion may be of interest to those studying electromagnetism, quantum mechanics, or anyone curious about the nature of light and its interactions with charged particles.

jlyu002@ucr.e
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Since it does have an electric field, if we were to put a positive test charge near it, would it exhibit an inward field or an outward field?
 
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A photon doesn't produce an electric field, it is a neutral particle as you stated in the title. Photons are the excitations of the electric field.
 
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A test charge would move first in one direction, then the other.
 
Vanadium 50 said:
A test charge would move first in one direction, then the other.

And it does this, frequently, up in the ionosphere - or you wouldn't hear HF transmissions from all over the World.
 
Vanadium 50 said:
A test charge would move first in one direction, then the other.

Do you know of any video or specific experiments that show this behavior? I'm really interested.
 
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

"Direct measurement of light waves", E. Goulielmakis et al., Science 305, 1267 (2004). http://www.attoworld.de/Documents/papers/Science/Science305p1267_2004.pdf.

These are not charges at rest moving back and forth, but you see a modulation in the kinetic energy/momentum of moving electrons, which is close enough, I guess.
 
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

Turn on a radio. It uses this exact behavior.
 
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

Yes. It's called a "radio antenna".
 
Funny, now I'm curious too... can there exist a photon without some sort of external/residual/whatever of a field? I know the e and m fields balance/cancel when traveling at c... really? And apologies, holiday weekdnd, kinda been drinking.
 
  • #10
WhatIsGravity said:
Funny, now I'm curious too... can there exist a photon without some sort of external/residual/whatever of a field? I know the e and m fields balance/cancel when traveling at c... really? And apologies, holiday weekdnd, kinda been drinking.

A photon is the quanta of interaction of the EM field, so no, it cannot exist without the EM field.
 
  • #11
Drakkith said:
A photon is the quanta of interaction of the EM field, so no, it cannot exist without the EM field.

Does a photon create it's own EM field, as it goes, or is that field just there?
 
  • #12
WhatIsGravity said:
Does a photon create it's own EM field, as it goes, or is that field just there?

To my knowledge, the field always exists.
 

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