What is the velocity of light in uniformly rotating frame?

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Discussion Overview

The discussion centers on the velocity of light in a uniformly rotating frame of reference, particularly comparing it to inertial frames as described by special relativity (STR) and general relativity (GTR). Participants explore the implications of non-inertial frames on the speed of light and related concepts.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that the speed of light in vacuum is constant in all inertial frames, but question how this applies in non-inertial frames such as one with uniform angular velocity.
  • Others argue that in a non-inertial frame, the speed of light is not limited and can vary, suggesting it can be arbitrarily large or small.
  • A participant highlights that the answer depends on how the rotating frame is set up, particularly regarding clock synchronization.
  • There is a discussion about the Earth's rotation and its effect on the perceived motion of distant stars like Proxima Centauri, with calculations presented for the speed of Proxima Centauri in a rotating frame.
  • Some participants emphasize the triviality of the Earth's velocity around the Sun in this context, suggesting to focus solely on the Earth's rotation.

Areas of Agreement / Disagreement

Participants express differing views on the implications of non-inertial frames for the speed of light, with no consensus reached on how to interpret these effects or the calculations presented.

Contextual Notes

There are unresolved assumptions regarding the definitions of speed in non-inertial frames and the specific setup of the rotating frame, which may affect the conclusions drawn.

Who May Find This Useful

This discussion may be of interest to those studying relativity, particularly in understanding the nuances of light speed in different reference frames, as well as those exploring the implications of general relativity.

pallab
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S'-frame of reference has uniform angular velocity with respect to the frame S. what is the velocity of light in S frame w.r.t S' ?
 
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pallab said:
S'-frame of reference has uniform angular velocity with respect to the frame S. what is the velocity of light in S frame w.r.t S' ?
What are your thoughts? What are the Relevant Equations? Is this for schoolwork?
 
berkeman said:
What are your thoughts? What are the Relevant Equations? Is this for schoolwork?
NO.
My friend asked me this question.but I don't know about GTR.I studied STR .According to postulate speed of light in vacuum is same in all inertial frames.But a frame with uniform angular velocity is not inertial frame and the speed of light which has same value not the velocity.
 
pallab said:
NO.
My friend asked me this question.but I don't know about GTR.I studied STR .According to postulate speed of light in vacuum is same in all inertial frames.But a frame with uniform angular velocity is not inertial frame and the speed of light which has same value not the velocity.
Start with something easy. What is the speed of Proxima Centauri (4.2 light years from earth) in a frame of reference anchored to the rotating earth?
 
jbriggs444 said:
Start with something easy. What is the speed of Proxima Centauri (4.2 light years from earth) in a frame of reference anchored to the rotating earth?
when the Earth approaches toward the Proxima Centauri its speed is more than the speed ,when Earth moves away from it,like the Earth's movement around the sun.
 
pallab said:
when the Earth approaches toward the Proxima Centauri its speed is more than the speed ,when Earth moves away from it,like the Earth's movement around the sun.
The Earth's velocity around the Sun is trivial. Ignore it. Forget about the Sun entirely.

The Earth is rotating once every 24 hours [approximately]. You anchor a frame of reference to it at this rotation rate. How does Proxima Centauri move from the point of view of this reference frame?
 
pallab said:
speed of light in vacuum is same in all inertial frames.But a frame with uniform angular velocity is not inertial frame
This is the key point. The speed of light is not limited in a non-inertial frame. It can be arbitrarily large or small.
 
The shortest totally correct answer is it depends on how you set up your rotating frame. Of specific interest is how you synchronize clocks in your "frame".
 
  • #10
jbriggs444 said:
The Earth's velocity around the Sun is trivial. Ignore it. Forget about the Sun entirely.

The Earth is rotating once every 24 hours [approximately]. You anchor a frame of reference to it at this rotation rate. How does Proxima Centauri move from the point of view of this reference frame?
v=2πR/T
now for Earth T=86400 sec.
and R=4.2 light years i.e. (9.46*1015)*4.2
so,v=2.8*1012 m/s , >c
 
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