Photon Time: 10B Years, 0 Seconds?

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Discussion Overview

The discussion revolves around the concept of time experienced by photons traveling at the speed of light, particularly in the context of special relativity. Participants explore the implications of time dilation and the validity of discussing a photon's frame of reference from its creation to absorption, raising questions about redshift and the nature of light travel over vast distances.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that in the reference frame of a photon, no time elapses during its journey, despite it traveling for billions of years from an external perspective.
  • Others argue against the validity of defining a proper frame of reference for photons, suggesting it is meaningless within the framework of special relativity.
  • A participant raises the issue of redshift, questioning how a photon can experience redshift if it has no time to exist in its own frame.
  • Some participants express that while discussing a photon's journey from creation to absorption may seem meaningful, it should be approached from the perspective of an observer rather than the photon itself.
  • There is a suggestion that it is possible for a photon emitted now to be detected in the future, alongside another photon emitted later, raising questions about simultaneity from different reference frames.

Areas of Agreement / Disagreement

Participants exhibit disagreement on the validity of discussing a photon's frame of reference, with some asserting it is meaningless while others believe it can aid understanding. The discussion remains unresolved regarding the implications of time experienced by photons and the nature of redshift.

Contextual Notes

Limitations include the challenge of applying Lorentz transformations to a photon's frame and the dependence on definitions of time and reference frames in relativity.

chaszz
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From thousands of galaxies dotting Hubble deep sky photographs, photons have been traveling for say, ten billion years before they reach the telescope's lens. But by definition when something travels at the speed of light the passage of time slows down to zero. So is it accurate to say that in their own reference frame, these photons over the course of 10 billion years have actually had not even a second elapse?
 
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I don't think you can define a proper frame moving at the speed of light relative to another inertial reference frame.
 
I think this is correct, the gamma factor goes to infinity, so I think that’s what the Lorentz equations tell us. That does bring up some weird ideas, like when a photon gets red shifted away by its perspective it never had time to exist so how did it have time to redshift?
 
redshifted relative to whom?
 
Dickfore is absolutely correct here. It is meaningless to talk about a photon frame in the context of special relativity (or any existing theory that I can think of)
 
nnnm4 said:
Dickfore is absolutely correct here. It is meaningless to talk about a photon frame in the context of special relativity (or any existing theory that I can think of)

I agree that it may be meaningless to talk about a photon's frame of reference from a mathematical point of view, as 'Frames of Reference are used for a specific purpose in relativity.

But I don't see why it is meaningless to discuss what happens to photon from creation to absorption. This is after all, a real situation. Particularly if it helps the OP grasp a concept. Even Einstein imagined traveling along side a light beam, which we know is meaningless, but it certainly helped him.

So why is it that it is not valid to talk about what happens to a photon from the time we create one to the time we would observe it being absorbed?

So maybe another way of asking the OP’s question might be this.

If I switch my torch on and point it to a particular area of the sky, is it possible that in 10 billion years or so, assuming we are still around, that someone may detect that photon. EDIT: And obviously assuming life elsewhere.

If so, then in 100 years time, if my grandson repeats our family tradition of shining bright torches in a particular direction in the sky, is it possible that the same device that detected my photon, could detect my grandson’s photon simultaneously, from their frame of reference?
 
rede96 said:
I agree that it may be meaningless to talk about a photon's frame of reference from a mathematical point of view, as 'Frames of Reference are used for a specific purpose in relativity.

But I don't see why it is meaningless to discuss what happens to photon from creation to absorption. This is after all, a real situation. Particularly if it helps the OP grasp a concept. Even Einstein imagined traveling along side a light beam, which we know is meaningless, but it certainly helped him.

So why is it that it is not valid to talk about what happens to a photon from the time we create one to the time we would observe it being absorbed?

So maybe another way of asking the OP’s question might be this.

If I switch my torch on and point it to a particular area of the sky, is it possible that in 10 billion years or so, assuming we are still around, that someone may detect that photon.

If so, then in 100 years time, if my grandson repeats our family tradition of shining bright torches in a particular direction in the sky, is it possible that the same device that detected my photon, could detect my grandson’s photon simultaneously, from their frame of reference?

Who says that THAT is meaningless? We consider that ALL THE TIME! But we consider that in our reference frame, not the photon's!

What is meaningless is to do a Lorentz transformation to the photon's frame. Don't believe me? Try it!

To the OP: Please read the FAQ subforum here.

Zz.
 
ZapperZ said:
Who says that THAT is meaningless? We consider that ALL THE TIME! But we consider that in our reference frame, not the photon's!

What is meaningless is to do a Lorentz transformation to the photon's frame. Don't believe me? Try it!
Zz.

Been there, tried that lol. Yes that was my point, but phrased a lot better. :)thanks.
 

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