Why is photon massless particle?

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Discussion Overview

The discussion revolves around the nature of photons, specifically why they are considered massless particles. Participants explore concepts from quantum mechanics and relativity, questioning the implications of masslessness and the characteristics of photons as both particles and waves.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the nature of photons, questioning how something that exists in space and time can be massless and what it consists of.
  • Another participant clarifies that photons are not ordinary particles but are defined as having a clump of energy without a definite physical boundary, suggesting that existence does not necessitate mass.
  • A reference is made to the book "Beyond the God Particle," which explains that photons do not interact with the Higgs field, allowing them to remain massless and travel at maximum speed.
  • One participant raises the possibility that photons might have a very small mass that is currently undetectable, expressing skepticism about the ability to definitively prove that they are massless without assuming it.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of photon mass. While some argue that photons are definitively massless due to their interaction with the Higgs field, others suggest the possibility of an undetectable small mass, indicating ongoing debate and uncertainty.

Contextual Notes

The discussion highlights limitations in understanding the implications of masslessness and the nature of photons, as well as the dependence on definitions related to mass and existence.

disky
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i'm still wondering,
i know a bit of quantum mechanics and general relativity. well... very very little, if photon is a particle, it must be "something" right? i mean, something that exist in this space and time. why is "something" that "exist" don't have a mass? what is it consist of? or something that really small is different with something big like table? or is photon just a wave that going through space and time? but if it is just a wave, how does it come through vacuum space? please help me, I've done browsing but i got nothing. i am still at high school and the farthest thing i got is classical physics and really excited to modern one but too dumb-_-. and i am new here. thank you
 
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disky said:
i'm still wondering,
i know a bit of quantum mechanics and general relativity. well... very very little, if photon is a particle, it must be "something" right? i mean, something that exist in this space and time. why is "something" that "exist" don't have a mass? what is it consist of? or something that really small is different with something big like table? or is photon just a wave that going through space and time? but if it is just a wave, how does it come through vacuum space? please help me, I've done browsing but i got nothing. i am still at high school and the farthest thing i got is classical physics and really excited to modern one but too dumb-_-. and i am new here. thank you

This is a very familiar question, and I suggest you browse the forums, especially the Quantum Physics forum, for a bit to see all the ad nauseum answers that have been given.

A photon isn't an ordinary "particle". Rather, it has been defined as having a clump of energy. It has not been defined as having a definite physical boundary in real space, the way we see a ball, for example.

Secondly, for something to "exist", it must be detectable. We must be able to detect and measure its characteristics. That's it. Nothing here says that for something to exist, it must have a mass. Before quantum mechanics and special relativity came along, we detected light regularly. Yet, none of the theories at that time showed a "particle" picture of light, and thus, no question on whether it has a mass.

The lesson that you should learn here is to think carefully what your logic and sequence of thinking is. Is the existence of A automatically implies the existence of B?

I can already anticipate your subsequent questions on this (if it has "energy", then https://www.physicsforums.com/threads/do-photons-have-mass.511175/ "). You should also read, before you go any further, the FAQ that we currently have on this topic.

Zz.
 
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In the book "Beyond the God particle" Lederman try to explain in a simple manner why photon is massless. The responsable is the Higgs field that permeates all the universe: for example in the case of the weak interaction, being a beaking simmetry, the bosons interact with it acquiring mass. He says that for the particles with mass the chirality oscillates from a right to left handedness while for massless ones it is unique and then they can't interact with Higgs field: so the photon cant't obtain mass and they are free to go at maximum speed.
 
I don't know that we can truly rule out that the photon has a very small mass that we simply can't measure. I doubt that is the case, but it will be hard to theoretically show that it must be massless without assuming that it is massless.
 

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