Distance light travels in a relatively moving frame?

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Discussion Overview

The discussion revolves around the behavior of light in relation to a particle moving at a significant fraction of the speed of light (0.5c) and a light source (lightbulb) that is at rest relative to the particle. Participants explore the implications of measuring the speed of light from the moving particle's frame of reference and clarify terminology regarding relative motion.

Discussion Character

  • Exploratory
  • Conceptual clarification

Main Points Raised

  • One participant proposes that when a particle moving at 0.5c passes a lightbulb, the light wave will travel a distance of ct in the particle's reference frame, where t is any time measured by the particle.
  • Another participant questions the terminology used, noting a contradiction in stating that the particle and lightbulb are at relative rest while also describing the particle as moving at 0.5c.
  • A clarification is made that the particle is indeed moving at 0.5c relative to the lightbulb.
  • There is an affirmation that the light wave will travel a distance of ct from the point of measurement in the particle's frame.

Areas of Agreement / Disagreement

Participants generally agree on the behavior of light as described, but there is some initial confusion regarding the terminology of relative motion, which is clarified later in the discussion.

Contextual Notes

The discussion includes potential misunderstandings about relative motion and terminology, which could affect the interpretation of the scenario presented.

Reikoku
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I was wondering if say.. you have a particle moving at 0.5c in the +x direction and a lightbulb at relative rest to the particle.
The particle passes the lightbulb at t_{0}
The lightbulb then flashes, the wave reaches the particle at a particular point, and the speed of light is then measured (by the particle) to be c. Does this then mean that the light wave will then travel a distance of ct from that point in the reference frame of the particle; t being any point in time that the particle wishes to measure the distance of the light wave from it.
 
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Reikoku said:
I was wondering if say.. you have a particle moving at 0.5c in the +x direction and a lightbulb at relative rest to the particle.
The particle passes the lightbulb at t_{0}
If the particle and lightbulb are at relative rest, how can they pass each other?
 
Doc Al said:
If the particle and lightbulb are at relative rest, how can they pass each other?

Oh am I using the wrong terminology? I meant to say that the particle is moving with 0.5c compared to the lightbulb.
 
Reikoku said:
I meant to say that the particle is moving with 0.5c compared to the lightbulb.
OK.
Reikoku said:
Does this then mean that the light wave will then travel a distance of ct from that point in the reference frame of the particle; t being any point in time that the particle wishes to measure the distance of the light wave from it.
Yes.
 
Thanks Doc Al, that's helped clear up confusion.
 

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