Speed of light in non inertial frames

In summary, the constancy of c is a bit confusing for new students of special relativity. It depends on the frame of reference and the observer's motion.
  • #1
obnoxiousris
21
0
sorry to bring this up again, i have just started special relativity and the constancy of c is a bit confusing, i get how c is the same in all inertial frames but what about accelerating frames? do observers in acceleration still see c as a constant? i have seen many forum posts and they always have two people saying the opposite things, can somebody set me straight on this?

also, if the observer is moving at 0.99c and he will see c still being c, but what about a stationary observer looking at both? will he see both of them traveling almost at the same speed?
 
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  • #2
It really depends on which clocks and rulers you use. If you have an accelerating frame, by the equivalence principle you'll have something that looks like a local gravitational field. This means that clocks that are "up" higher in this field will run faster than clocks that are "lower" - they won't all run at the same rate.

If you use local clocks and local rulers, things are simple - the speed of light is always 'c', it doesn't matter whether you accelerate or not.

However, you will not find that the path that light travels is given by the equation x=ct in an accelerated frame - the coordinate expression for light's path is more complex than that.
 
  • #3
Light always travels at C in a vacuum. The postulate of SR states the invariance of the speed of light. This invariance is without caveats barring the medium traveled through.
 
  • #4
obnoxiousris said:
sorry to bring this up again, i have just started special relativity and the constancy of c is a bit confusing, i get how c is the same in all inertial frames but what about accelerating frames? do observers in acceleration still see c as a constant? i have seen many forum posts and they always have two people saying the opposite things, can somebody set me straight on this?
Read this: https://www.physicsforums.com/showpost.php?p=2885196&postcount=4

also, if the observer is moving at 0.99c and he will see c still being c, but what about a stationary observer looking at both? will he see both of them traveling almost at the same speed?
Yes. The 'stationary' observer will see the 'moving' observer moving at 0.99c and the light moving at c.
 
  • #5
thanks guys, really helped!
 

1. What is the speed of light in a non-inertial frame?

The speed of light in a non-inertial frame is the same as the speed of light in an inertial frame. This is a fundamental principle of Einstein's theory of relativity. In other words, the speed of light is constant and does not change regardless of the frame of reference.

2. How does the speed of light behave in a non-inertial frame?

The speed of light behaves the same way in a non-inertial frame as it does in an inertial frame. It travels at a constant speed of approximately 299,792,458 meters per second in a vacuum, regardless of the motion of the observer or the source of light.

3. Can the speed of light be exceeded in a non-inertial frame?

No, the speed of light cannot be exceeded in any frame of reference. According to Einstein's theory of relativity, the speed of light is the maximum speed at which all matter and information can travel. This applies to both inertial and non-inertial frames.

4. How does the speed of light relate to time dilation in non-inertial frames?

In non-inertial frames, time dilation occurs due to the acceleration of the frame. This means that time passes slower for an observer in a non-inertial frame compared to an observer in an inertial frame. However, the speed of light remains constant for both observers, regardless of their relative motion.

5. Is the speed of light affected by gravity in a non-inertial frame?

Yes, the speed of light is affected by gravity in a non-inertial frame. According to Einstein's theory of general relativity, gravity can cause the fabric of space-time to bend, which in turn can affect the path of light. This leads to phenomena such as gravitational lensing, where light is bent by the gravity of massive objects.

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