Lifespan of a Photon: Debunking the Myth of Time Travel

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Discussion Overview

The discussion centers around the lifespan of a photon and the implications of its movement along a null worldline. Participants explore concepts from quantum physics and general relativity, questioning the relationship between a photon's trajectory and its stability as a particle.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that a photon moves only through space and not time, which they believe contributes to its long lifespan.
  • Others clarify that light moves along a null worldline and that this is a characteristic of photons, which cannot be described by classical trajectories.
  • There is a distinction made between photons and massive particles, with the latter moving along timelike worldlines.
  • Some participants express confusion regarding the implications of a photon’s movement and its lifespan, questioning whether its long lifespan is a result of its null worldline.
  • One participant argues that photons are stable particles according to the standard model of particle physics, while another mentions calculations suggesting that photons can decay, albeit over extremely long timescales.
  • There is a discussion about the potential for photons to have a non-zero mass and how this would affect their classification and decay properties.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether photons can decay or if their long lifespan is directly tied to their movement along a null worldline. Multiple competing views remain regarding the implications of mass and stability of photons.

Contextual Notes

Participants highlight the need for precision in scientific discussions, particularly regarding the standard model of particle physics and the implications of popular science interpretations. There are unresolved questions about the conditions under which photons might decay and the assumptions underlying various claims.

  • #31
rolnor said:
This is bullying, not nessecary and not science
No, no, it's not meant as bullying at all. Over the years at PF we have come to understand how important it is to tune the level of responses to the level of understanding of the OP asking the question. That is why in many of our technical PF forums we use the prefix system on the thread title, to better help responders know how to respond to the OP's question.
 
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  • #32
rolnor said:
This is bullying, not nessecary and not science
OK, so what level do you want an answer? Graduate level texts have been suggested. Is this an adequate answer? If not, what do you want instead?

Lack of mental telepathy is not the same as bullying.
 
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  • #33
I am grateful for all answers that help me understand this matter. One comment seemed unecessary. Maybe I missinterpreted the intention.
 
  • #34
vanhees71 said:
It's not ignorance! It's just that relativistic QFT is a quite difficult subject, and it's impossible to understand it without the adequate math. In addition it's also not fully established from a strict mathematical point of view. It needs time to learn all this. For me the most concise introductory treatment is given in

S. Coleman, Lectures of Sidney Coleman on Quantum Field
Theory, World Scientific Publishing Co. Pte. Ltd., Hackensack
(2018), https://doi.org/10.1142/9371

Large parts of this book is also freely available from the arXiv:

https://arxiv.org/abs/1110.5013

More details, particularly the emphasis of the importance of the microcausality constraints can be found in the 3-volume textbook series by Weinberg, Quantum Theory of Fields.

Complementary to that is

A. Duncan, The conceptual framework of quantum field
theory, Oxford University Press, Oxford (2012).
Thanx a lot now I have some reading to do.
 
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