Why do we say photons travel ?

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    Photons Travel
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Discussion Overview

The discussion revolves around the nature of photons and the concept of their travel. Participants explore whether photons can be considered to travel in the traditional sense, the implications of their properties, and the relationship between electromagnetic waves and photons. The scope includes theoretical considerations, conceptual clarifications, and some speculative ideas.

Discussion Character

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

Main Points Raised

  • Some participants argue that photons, while having zero rest mass, are not material particles and do indeed travel from their source to points of interaction.
  • Others propose that instead of saying photons travel, it might be more accurate to say that energy is communicated, suggesting that nothing physically travels through space.
  • A participant questions the idea of a medium, asserting that a vacuum is not a medium, while another participant affirms that electromagnetic waves do not require a medium for propagation.
  • There is a suggestion that photons may not travel at all, but rather that electromagnetic waves are generated at the source and detected at another point, raising questions about the nature of photons and their existence in the absence of interactions.
  • Some participants discuss the relationship between electromagnetic waves and photons, with one stating that the electromagnetic wave is the photon, while another expresses confusion over this assertion in light of conflicting information from literature.
  • There is a discussion about the peculiarities of photon behavior, including their existence in empty space and the conditions under which they can be said to exist or not exist.
  • One participant raises a hypothetical scenario regarding the behavior of photons in relation to radio signals and their wavelength, questioning how photons could be said to "die" at the receiver.
  • Another point raised is that light exhibits particle-like properties only when interacting with matter, suggesting that photons may not exist independently without such interactions.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of photons and their travel. There is no consensus on whether photons travel in the traditional sense or if they exist independently of interactions.

Contextual Notes

Participants highlight limitations in understanding the nature of photons, including the dependence on definitions of medium and the conditions under which photons can be said to exist. The discussion also reflects unresolved questions about the implications of electromagnetic waves and their relationship to photons.

Who May Find This Useful

This discussion may be of interest to those exploring the fundamental nature of light, the behavior of photons, and the theoretical implications of electromagnetic theory in physics.

  • #31
It never exhibits its wave and particle natures simultaneously.

Good point. I had never fully considered that. I guess it depends in part on what is meant by "exhibits."

Can one realize a photon's pure wave nature from its nonsimultaneous and pure particle nature?

Is a wave packet a single photon imaginary in part, or perhaps always a multiplicity of photons?

Might wave packets interact with other wave packets?
 
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  • #32
... if you try to observe the wave nature of a photon and then try to observe its particle nature... how do you know you are still looking at the same photon? don't they all look pretty similar...

I would say science is about measurement, all we can know is what we measured in a particular interaction and we can only try to guess (educated) what happens between measured interactions...
 
  • #33
Loren Booda asks,
Is a wave packet a single photon imaginary in part, or perhaps always a multiplicity of photons?
I'm not sure what you mean by 'imaginary in part'.

It might seem intuitive that you can produce a photon by chopping a light beam into a very short pulse of light. The result will have a spread of frequencies ( Fourier modes ) and looks mathematically like a wave-packet, a wave packet being a superposition of many close frequencies. It is also localizable like a particle. But it is controversial to refer to that as a photon.

Single photon sources are notoriously difficult to make, and I haven't seen completely convincing experimental results, but I may not be up-to-date with the technology.

axawire, I agree with your view that we can only guess what goes on between obervations.
 
  • #34
Is a wave packet a single photon imaginary in part...
In other words, can't the photon before measurement be represented as a vector oscillating in complex space? A Fourier transform, such as accompanies a measurement, might convert a wave packet into a photon, or a wave into a wave packet.

Single photon scintillations have been observed for decades.
 
  • #35
Branching this question

lightarrow said:
Can a photon exist in absence of interaction? Perhaps we should start a new thread about it. (My answer is no, but I'm open to every possibility).

I think it might be beneficial to mkbh_10's question if there is agreement on terminology. I've posted this question as "When is a photon a photon"
 

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