Are Photons Real? New Study Challenges Assumptions

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Discussion Overview

The discussion revolves around the nature of photons and their reality, prompted by a preprint suggesting that photons can be described as wave packets with a transverse extent. Participants explore the implications of this characterization, questioning the distinction between mathematical models and observable entities in physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Philosophical inquiry

Main Points Raised

  • Some participants propose that photons are constructs used to model interactions between matter, while others argue that they are real entities because they interact with other things.
  • A participant questions the validity of the preprint, suggesting it appears "iffy" due to its use of certain notations.
  • There is a discussion about the definition of "real," with some asserting that anything that interacts is real, while others challenge the circularity of this definition.
  • Some participants express skepticism about whether concepts like magnetic fields or wavefunctions can be considered real, suggesting they are merely mathematical constructs.
  • Philosophical questions arise regarding the nature of reality in physics, with references to the limitations of models and the empirical basis of scientific inquiry.
  • Several participants emphasize that the discussion strays into philosophical territory, which may not be directly relevant to physics.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of photons or the definition of reality. Multiple competing views remain, with some asserting the reality of photons and others questioning the validity of that assertion based on philosophical grounds.

Contextual Notes

The discussion includes unresolved philosophical questions about the nature of reality and the role of mathematical models in physics. There are references to specific terminologies and concepts that may not be universally agreed upon.

Who May Find This Useful

This discussion may be of interest to those exploring the philosophical implications of quantum mechanics, the nature of physical entities, and the relationship between mathematics and physics.

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Recently I've stumbled across a preprint in which the author describes a photon is a wave packet and even suggests a transverse extent.

I find it strange, as my understanding so far has been that a photon (and the EM field as such) is a construct used to model certain observed interactions between particles of matter.

Yes, I am assuming matter to be real, as something that interacts with each other. While force fields are mathematical models of those interactions.

https://arxiv.org/ftp/arxiv/papers/1706/1706.04475.pdf
 
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Why wouldn't light be real?
 
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log0 said:
Yes, I am assuming matter to be real, as something that interacts with each other. While force fields are mathematical models of those interactions.

But matter also interact with the force fields (eg. Compton scattering).
 
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Many fields are real, among them the electromagnetic one. For me "real" means it's an observable entity of Nature, and indeed electromagnetic fields are observable. E.g., light and thus literally all we see is just a manifestation of the electromagnetic field. Another manifestation are the forces on objects you observe due to the presence of electrostatically charged bodies or the force between a permanent magnet and the door of your fridge etc. etc. In fact according to the most precise theory ever, the Standard Model of particle physics, all matter is also the manifestation of various (quantum) fields, and since you can observe this matter also these fields are "real".
 
Are forces real? Or are they just a mathematical concept "invented" to model how we describe natural phenomena? :smile:
 
What does it mean to be real? That's the Philosophy Department, two doors down. How do we know anything is real? How do we know we're not just brains in vats?

This is not physics. In physics, "just a model" is all you get.
 
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log0 said:
Recently I've stumbled across a preprint in which the author describes a photon is a wave packet and even suggests a transverse extent.

I find it strange, as my understanding so far has been that a photon (and the EM field as such) is a construct used to model certain observed interactions between particles of matter.

Yes, I am assuming matter to be real, as something that interacts with each other. While force fields are mathematical models of those interactions.

https://arxiv.org/ftp/arxiv/papers/1706/1706.04475.pdf
That paper looks very iffy.
 
Vanadium 50 said:
What does it mean to be real? That's the Philosophy Department, two doors down. How do we know anything is real? How do we know we're not just brains in vats?

This is not physics. In physics, "just a model" is all you get.
Physics is an empirical science, and "real" in the sense of the natural sciences is what can be reproducibly and objectively observed. Models and theories are the way to organize the empirically found knowledge in an efficient way.
 
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He gave the definition of "real" he uses. Things that interact with other things are real. Photons do, so they are real.
 
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  • #10
I don't think he did - he would seem to exclude a magnetic field as real. But in any event, this is not physics. It's just not something physics concerns itself with. Is a Lagrangian real? Are image charges real? Wavefunctions? This is a fast way to get tied up in knots. Unproductive knots.
 
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  • #11
Vanadium 50 said:
I don't think he did - he would seem to exclude a magnetic field as real.
He would but he shouldn't. It is real.
Vanadium 50 said:
But in any event, this is not physics.
No, it is not. But that doesn't mean in it doesn't matter for physics. Mathematics is not physics but is usually not dismissed.
Vanadium 50 said:
It's just not something physics concerns itself with. Is a Lagrangian real? Are image charges real? Wavefunctions? This is a fast way to get tied up in knots. Unproductive knots.
These are not real. They are mathematical objects (dont know what the image charges are).
 
  • #12
martinbn said:
He gave the definition of "real" he uses. Things that interact with other things are real. Photons do, so they are real.
What if the object with which they interact is not "real"? This is a fundamentally circular definition whose utility eludes me. I guess it proves self -consistency which I think was the extent of @vanhees71 argument
 
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  • #13
hutchphd said:
What if the object with which they interact is not "real"? This is a fundamentally circular definition whose utility eludes me. I guess it proves self -consistency which I think was the extent of @vanhees71 argument
By this definition it cannot be not real. If it interacts it is real. It is symmetric not circular.
 
  • #14
martinbn said:
By this definition it cannot be not real. If it interacts it is real. It is symmetric not circular.
This is foundationalism instead of coherentism..... but remember
Vanadium 50 said:
What does it mean to be real? That's the Philosophy Department, two doors down. How do we know anything is real? How do we know we're not just brains in vats?

This is not physics. In physics, "just a model" is all you get.
.
 
  • #15
DrClaude said:
That paper looks very iffy.
When a not so old paper uses ##h## rather than ##\hbar##, it's usually wrong. :wink:
 
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  • #17
Don't forget M. Williams, The Velveteen Rabbit.
 

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