Does a Photon Experience Time or Space During Travel?

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Discussion Overview

The discussion revolves around the conceptual understanding of whether a photon experiences time or distance during its travel between two points in space. Participants explore this question through thought experiments and references to special relativity, touching on implications for the nature of photons and their interactions with matter.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question whether it is coherent to speak of a photon's perspective, arguing that there is no inertial frame where a photon is at rest, thus making concepts of time and distance irrelevant from that viewpoint.
  • Others reference the idea that photons do not experience time, citing various physicists and popular science interpretations, while noting that this claim can be misinterpreted or oversimplified.
  • A participant mentions the claim that photons can take a long time to travel from the Sun's core to its surface, suggesting that this journey is akin to "jumping from atom to atom," raising questions about the nature of time and distance for photons.
  • Concerns are raised about the implications of photons not experiencing time or distance, leading to speculation about the existence of dimensions for entities traveling at the speed of light.
  • Some participants discuss the effects of gravitational and spatial warping on photons, such as redshift and blueshift, indicating that these phenomena suggest some form of change occurs during a photon's travel.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether photons experience time or distance. There are multiple competing views, with some asserting that these concepts do not apply to photons, while others challenge or refine these claims.

Contextual Notes

Limitations include the ambiguity in interpretations of statements made by physicists regarding photons and time, as well as the unresolved nature of how to reconcile the behavior of photons with the principles of special relativity.

  • #31
PeterDonis said:
Stephanus said:
Not only the proton is never at rest. It always travels at the speed of light.
It just hits me.
1. Proton is not time like or space like. It's light light. Is this true?
2. Proton is not time like, so it has no proper time. Is this true?
3. Proton is not space like, so it has no proper distance. Is this true?
I assume you mean "photon". Yes, a photon is lightlike, not timelike or spacelike. (More precisely, a photon's 4-momentum, the 4-vector that describes it, is lightlike.)
What?? I typed PROTON four times??
PeterDonis said:
The concept of "proper time" only applies to timelike objects, so yes, it doesn't apply to a photon.
The concept of "proper distance" only applies to spacelike intervals, so yes, it doesn't apply to a photon, since a photon's worldline is null (lightlike).
According to whatever inertial frame we are using. Photons themselves are lightlike, but you can certainly describe their trajectories using inertial frames. The concepts of "proper time" and "proper distance" don't apply along a photon's worldline, but with respect to any inertial frame (i.e., with respect to any timelike observer), photons do take time to travel and cover distance while traveling.
I "suspected" that much.
I already knew that:
Timelike events has proper time, no proper distance.
Spacelike events has proper distance, no proper time.
I just realized that, PHOTON wl is not time like, but it's not spacelike either.
Never tought about "light ray" in space time diagram.
I hope there's no silly typo this time!

[Add]
Stephanus said:
1. Proton is not time like or space like. It's light light. Is this true?
Did I type "lightlight"? Supposed you already knew that it's light like
 
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  • #32
PeterDonis said:
According to whatever inertial frame we are using.
Oh.
PeterDonis said:
Photons themselves are lightlike, but you can certainly describe their trajectories using inertial frames.
And it's always 450 degree right?
PeterDonis said:
The concepts of "proper time" and "proper distance" don't apply along a photon's worldline, but with respect to any inertial frame (i.e., with respect to any timelike observer), photons do take time to travel and cover distance while traveling.
Yes.
 
  • #33
Stephanus said:
And it's always 45 degree right?

In a standard spacetime diagram in flat spacetime, yes.
 

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