How come there is a particle with zero mass?

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Discussion Overview

The discussion centers on the existence and nature of massless particles, specifically photons, exploring whether they are real entities or merely theoretical constructs. Participants examine the implications of massless particles in the context of physics, touching on concepts from quantum mechanics and electromagnetic theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question the reality of massless particles like photons, asking if they are merely "virtual" particles for understanding phenomena.
  • Others assert that photons are real entities, possessing energy and momentum, which allows them to interact with other particles.
  • One participant describes photons as electromagnetic waves, suggesting that this perspective may help clarify their interactions with electrons.
  • There is a discussion about the definition of particles, with one participant arguing that photons, like all particles in the standard model, are quantum systems described mathematically, and that massless particles can exist due to specific representations in quantum theory.
  • Another participant emphasizes that understanding interacting particles requires extensive knowledge beyond basic definitions.
  • One viewpoint suggests thinking of photons as packets of energy related to their wavelength, which transmit electromagnetic force, rather than as traditional particles.

Areas of Agreement / Disagreement

Participants express differing views on the nature of photons, with some asserting their reality and others questioning their classification as particles. The discussion remains unresolved regarding the implications of massless particles and their conceptual understanding.

Contextual Notes

The discussion reflects varying levels of mathematical and conceptual understanding among participants, with some acknowledging the complexity of interacting particles and the limitations of simpler explanations.

VodaVoda
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How come there is a particle with zero mass??

My question is probably very lame, please excuse me

how come there is some particle that has no mass and no charge? (like photons) does such a particle really exist? or they are just "virtual" particles thought for better understading of some phenomenons?
 
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They aren't really particles in everyday terms - a photon is a lump of electro-magnetic fields.
 


VodaVoda said:
My question is probably very lame, please excuse me

how come there is some particle that has no mass and no charge? (like photons) does such a particle really exist? or they are just "virtual" particles thought for better understading of some phenomenons?

A photon does not have any mass and charge, indeed, but it is real.

A photon has energy and momentum to transfer/obtain, so it can interact. If you remember that a photon is an electromagnetic wave that appears in the electron equations of motion, you will have a clear picture of photon-electron interaction. This interaction is rather strong, so it cannot be neglected without getting in trouble (infrared catastrophe).

Bob.
 
Last edited:


mgb_phys said:
They aren't really particles in everyday terms - a photon is a lump of electro-magnetic fields.
If a photon isn't a particle in everyday terms, then neither is an electron, or any of the other particles of the standard model. Particles are quantum systems with Hilbert spaces that are the representation spaces of irreducible projective representations of the Poincaré group (or representations of its covering group). Massless particles can exist because there are massless representations. Electrons can exist because there are massive spin 1/2 representations.

To the OP: I don't think there's any way to explain this in less mathematical language.

Actually, what I wrote is an oversimplification. That stuff only defines the mathematical description of non-interacting particles. There seems to be no end to how much you have to learn to really understand interacting particles.
 


photons are definitely real; if you're having trouble thinking of them as particles try thinking of them as packets of energy proportional to their wavelength which transmit the electromagnetic force
 

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