From a photon's reference frame

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Discussion Overview

The discussion revolves around the concept of a photon's reference frame and whether light still travels at the speed of light (c) from that perspective. Participants explore implications of special relativity, the nature of motion and time at light speed, and the relationship between frequency and energy of photons.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that according to special relativity, light always travels at c, regardless of the observer's reference frame.
  • Others argue that there is no inertial reference frame in which a photon is at rest, making questions about a photon's perspective problematic.
  • One participant suggests that if time is stopped for a photon, it raises questions about how photons can have different frequencies.
  • Another participant notes that the frequency of a photon is related to its energy, indicating that different photons can have different frequencies despite the concept of time being halted at light speed.
  • Some participants express confusion about the implications of two photons observing each other and whether they would perceive themselves as at rest.
  • There is a suggestion that the idea of a photon "seeing" anything is flawed, as time does not exist for a photon.

Areas of Agreement / Disagreement

Participants generally disagree on the implications of a photon's reference frame and the nature of time and motion at light speed. Multiple competing views remain regarding how to conceptualize these ideas within the framework of special relativity.

Contextual Notes

The discussion highlights limitations in understanding the behavior of photons from their own perspective, particularly regarding the definitions of time and motion at the speed of light. There are unresolved questions about how frequency relates to the concept of time for photons.

nealh149
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Does light still travel at c?
Thank you.
 
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According to special relativity, something going less than c will have light speed away from it at c. That property doesn't apply to something that is also going C, so I would say no.
 
Actually, the basis of Einstein's theories is that no matter what reference frame you observe from, light still travels at 'c'. A photon would therefore 'see' a parallel photon traveling at 'c' relative to itself.
 
An "object's reference frame" is a reference frame in which the object is at rest. But there is no inertial reference frame in which a photon (any photon) is at rest. Therefore questions about what things look like from the point of view of a photon don't have meaningful answers in the context of SR, strictly speaking.

Some people approach such questions by imagining the limiting case of an endless series of particles, each one moving faster than the preceding one, but I doubt that this is always valid.
 
Actually, a photon can't "see" anything so the problem does not arise!

More specifically, the question of motion of one photon relative to another does not arise because time is stopped at speed c. There is no "motion" relative to a photon.
 
Danger said:
Actually, the basis of Einstein's theories is that no matter what reference frame you observe from, light still travels at 'c'. A photon would therefore 'see' a parallel photon traveling at 'c' relative to itself.
This seems to be one of the hairier issues of relativity (to me anyway).

I would have guessed two photons would view each other as at rest. Since a photon *IS* traveling at the speed of light, from its frame of reference (considering itself the "at rest" observer), wouldn't the universe have infinite mass? And does time have any meaning to a photon?
 
I misspoke regarding the photon seeing anything. :redface: Forgot about the time factor. Anything that's even a teeny bit slower, though, will measure light traveling at c.
 
HallsofIvy said:
More specifically, the question of motion of one photon relative to another does not arise because time is stopped at speed c. There is no "motion" relative to a photon.
If time is stopped, then how do different photons have different frequencies?
 
Because you cannot look at things from the point of view of the photon (remember the inertial frame does not exist) then this question doesn't really make sense. The frequency of a photon is a quantum mechanical property that is related to it's energy. So photons have different frequencies because they have different energies.
 
  • #10
My point here that if time has stopped for a photon, then how can it change states at a fixed rate (it's frequency)?
 

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