Rotating Disc & Speed of Light ?

In summary, the discussion is about the Ehrenfest paradox, which raises questions about the effects of speed and acceleration on the size and shape of objects. The theory of relativity suggests that at high speeds, the circumference of a rotating disc will shrink and the space will become curved. However, there are alternative interpretations that suggest the space remains Euclidean and the material may bend or burst under the stress of shrinking.
  • #1
sabin
1
0
Rotating Disc & Speed of Light ?!

If a point on a disc's outer edge is traveling close to the speed of light and things contract in the direction of the acceleration at those speeds (relative to a stationary observer) would that mean the disc's radius stays the same but the circumfrance shrinks?

This has been hurting my head for days, hope someone can shed some light on it.
 
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  • #2
Choose a global set of coordinates and everything will be clear.

Carl
 
  • #4
sabin said:
If a point on a disc's outer edge is traveling close to the speed of light and things contract in the direction of the acceleration at those speeds (relative to a stationary observer) would that mean the disc's radius stays the same but the circumfrance shrinks?

This has been hurting my head for days, hope someone can shed some light on it.
That depends on your interpretation of what is happening.

In the theory of relativity the circumference indeed shrinks and as a result of the space in the rotating disk is no longer Euclidean but curved and pi is no longer a correct ratio. Furthermore by applying the equivalence principle we can deduce that the same applies to a gravitational field. :smile:

Alternatively one can interpret that the space remains Euclidean and that the shrinking will increase the stress on the material and that it either bends or bursts. :smile:
 

1. What is the concept of a rotating disc in relation to the speed of light?

The rotating disc experiment is a thought experiment used to understand the effects of relativity on the speed of light. It involves a rotating disc with a circumference of light detectors placed along its edge. According to Einstein's theory of relativity, the speed of light is constant in all inertial reference frames, meaning it should be the same for all detectors on the disc regardless of their position or direction of rotation.

2. How does the speed of light change on a rotating disc?

According to the theory of relativity, the speed of light is constant in all inertial reference frames. This means that the speed of light will not change on a rotating disc, regardless of its direction or speed of rotation. However, the measured distances and times between two points on the disc may appear to be different due to the effects of time dilation and length contraction.

3. Can the speed of light be exceeded on a rotating disc?

No, the speed of light cannot be exceeded on a rotating disc. According to Einstein's theory of relativity, the speed of light is the maximum speed at which energy, information, or matter can travel. This is a fundamental principle of the universe, and it applies to all inertial reference frames, including a rotating disc.

4. How does the speed of light affect time on a rotating disc?

The speed of light is constant in all inertial reference frames, meaning that it will not change on a rotating disc. However, the effects of time dilation can make it appear that time is passing at a different rate on different parts of the disc. This is due to the fact that the speed of light is the same for all observers, regardless of their relative motion.

5. What is the significance of the rotating disc experiment in understanding the speed of light?

The rotating disc experiment is significant because it helps us understand the effects of relativity on the speed of light. It demonstrates that the speed of light is constant in all inertial reference frames, and that time and distance are relative concepts. This experiment has been used to verify the predictions of Einstein's theory of relativity and has greatly contributed to our understanding of the universe.

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