# What is the velocity of light in uniformly rotating frame?

• I
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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berkeman
Mentor
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?

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.

jbriggs444
Homework Helper
2019 Award
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?

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.

jbriggs444
Homework Helper
2019 Award
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?

Dale
Mentor
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.

pervect
Staff Emeritus
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".

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

• jbriggs444