- #1
Izhaki
- 18
- 0
Hi,
In attempt to understand SR, a moving mirror clock is often given as part of a thought experiment, which leads to the dismissal of absolute time.
To save people reading, the short version of my question is this: This experiment assumes light is wave-like, right?
The long version of my question is this:
Just to make sure I understand the experiment correctly, here is my version of it:
Consider a glass tube with a torch on the top, pointing at a mirror at the bottom of the tube. Whenever the torch flashes, light moves toward the bottom mirror, reflects from it, and when it hits the torch again - a time tick has gone by.
If the tube is stationary with respect to an observer, the observer will agree with the tube on the tick time. However, if the tube is moving with respect to the observer, the tick will appear to her to take longer.
Now, to my knowledge, light is not affected by Newtonian momentum. That is, if a flying plane is releasing a tennis ball and a light beam downwards at the same time - the tennis ball path will be affected by the momentum of the plane, where the light will go straight down. Similarly, light from the sun is not affected by the suns motion in the milky way.
Based on this, consider that we replace the light torch, emitting hemispherical light, with a highly directional (line-like) laser beam. If the tube is moving fast enough, and the tube height is long enough, the light will never reach the bottom mirror - by the time it reaches this point in space the mirror has already moved.
The last paragraph was taking light as a particle-like phenomenon. I guess that you can solve this issue by thinking of light as a wave-like phenomenon, in which case, it will propagate like and expending sphere once omitted. Then, the light will never miss the moving mirror (as the mirror can't travel faster than light). Is this correct?
Thanks,
Izhaki
In attempt to understand SR, a moving mirror clock is often given as part of a thought experiment, which leads to the dismissal of absolute time.
To save people reading, the short version of my question is this: This experiment assumes light is wave-like, right?
The long version of my question is this:
Just to make sure I understand the experiment correctly, here is my version of it:
Consider a glass tube with a torch on the top, pointing at a mirror at the bottom of the tube. Whenever the torch flashes, light moves toward the bottom mirror, reflects from it, and when it hits the torch again - a time tick has gone by.
If the tube is stationary with respect to an observer, the observer will agree with the tube on the tick time. However, if the tube is moving with respect to the observer, the tick will appear to her to take longer.
Now, to my knowledge, light is not affected by Newtonian momentum. That is, if a flying plane is releasing a tennis ball and a light beam downwards at the same time - the tennis ball path will be affected by the momentum of the plane, where the light will go straight down. Similarly, light from the sun is not affected by the suns motion in the milky way.
Based on this, consider that we replace the light torch, emitting hemispherical light, with a highly directional (line-like) laser beam. If the tube is moving fast enough, and the tube height is long enough, the light will never reach the bottom mirror - by the time it reaches this point in space the mirror has already moved.
The last paragraph was taking light as a particle-like phenomenon. I guess that you can solve this issue by thinking of light as a wave-like phenomenon, in which case, it will propagate like and expending sphere once omitted. Then, the light will never miss the moving mirror (as the mirror can't travel faster than light). Is this correct?
Thanks,
Izhaki