Force on Photon? Interaction with Matter Explained

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Discussion Overview

The discussion revolves around the interaction between photons and matter, specifically addressing whether forces can be attributed to photons and how these interactions relate to classical and quantum physics frameworks. Participants explore concepts such as light pressure on solar sails and the applicability of Newton's Third Law in these contexts.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that when photons interact with matter, there is a force involved, questioning the relevance of Newtonian action-reaction principles.
  • Another participant argues against the notion of forces acting on photons, stating that interactions between matter and photons cannot be modeled using classical forces.
  • A participant raises the question of how to describe the pressure exerted by light on a solar sail, seeking clarification on the terminology and its relation to Newton's Third Law.
  • There is a discussion about mutual forces in the context of current-carrying wires, questioning whether these forces should be considered as action-reaction pairs or if photons should be included in this framework.
  • One participant emphasizes the distinction between classical and quantum physics, suggesting that the terminology used (photon vs. light) influences the theoretical framework applicable to the discussion.

Areas of Agreement / Disagreement

Participants express differing views on whether forces can be attributed to photons and how to frame the discussion within classical versus quantum physics. There is no consensus on the applicability of Newton's Third Law in this context, and the discussion remains unresolved.

Contextual Notes

Participants highlight limitations in the discussion, such as the dependence on the chosen theoretical framework (classical vs. quantum) and the implications of terminology used (photon vs. light). The relevance of Newton's laws in these interactions is also questioned without resolution.

bob012345
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TL;DR
Do we speak of forces on photons?
When photon interact with matter there is a force. Do we speak in terms of Newtonian action-reaction? When a photon exerts a force on matter -an action- do we speak of a force on the photon - a reaction? Thanks.
 
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We cannot speak of forces on photons. The interaction between "matter" and photons (i.e. quantized radiation) cannot be modeled by forces, let alone Newtonian ones.
 
Thanks. So if light has a pressure on a solar sail, what do we call it? And whatever we call it, then you woud argue that Netwon's Third Law just isn't relevant? Thanks.
 
In a simple example of two current carrying wires, there are mutual forces. Do we speak of the forces on each wire as action-reaction or as someone I'm debating with, each wire and the photons from the other wire as action-reaction? Or both?
 
bob012345 said:
So if light has a pressure on a solar sail, what do we call it?

We call it classical physics, not quantum physics. But you put this thread in the quantum physics forum and used the term "photon" in your OP, not "light". Which theoretical framework do you want to use?

If you want to use the classical framework, then you can open a new thread in the Classical Physics forum, not using the term "photon", to ask about how things like solar sails are modeled classically.

If you want to use the quantum framework, then the answer @dextercioby gave is correct.

Either way, this thread is closed.
 
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bob012345 said:
In a simple example of two current carrying wires, there are mutual forces. Do we speak of the forces on each wire as action-reaction or as someone I'm debating with, each wire and the photons from the other wire as action-reaction? Or both?

This question belongs in the Classical Physics forum, not here. Please start a new thread there if you want to discuss it. And again, the term "photon" has no place in a classical physics discussion.

This thread remains closed.
 

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