Light clock running faster than light?

In summary, the concept of a light clock running faster than light involves a theoretical scenario where a clock, using light pulses to measure time, appears to operate at superluminal speeds due to relativistic effects. However, according to the principles of relativity established by Einstein, nothing can travel faster than the speed of light in a vacuum. While the light clock may show rapid ticking from certain perspectives, it does not violate the fundamental laws of physics, as no information or matter is actually moving faster than light.
  • #1
tagehedin
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TL;DR Summary
Twin Paradox - Light clock speed up?
Twin Paradox.

I am on the outgoing rocket and look back at my stay at home twins light clock (two mirrors with a ray of light bouncing in between)

I get to the nearest star and on the outbound journey my twins clock apears to run slow.

When I turn around my plane of simultaneity shift and I see my twins clock run fast as I “catch up” to in respect to his plane of reference for the return trip.

Do I see the light-ray of his clock bouncing faster than the speed of light between the mirrors or do I see his clock contract so that the light-ray can bounce quicker in the shorter space?


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  • #2
tagehedin said:
TL;DR Summary: Twin Paradox - Light clock speed up?

Do I see the light-ray of his clock bouncing faster than the speed of light between the mirrors or do I see his clock contract so that the light-ray can bounce quicker in the shorter space?
It depends on the mathematical details of your non-inertial frame. Which you did not specify.

If you use something like radar coordinates (my preference) then the speed of light is always ##c## and there is no sudden jump in simultaneity
 
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Length contraction is a phenomenon between inertial frames, and you aren't using one. What you actually see is messy to compute; how you interpret it depends on your choice of non-inertial frame.
 
  • #4
tagehedin said:
When I turn around my plane of simultaneity shift and I see my twins clock run fast as I “catch up” to in respect to his plane of reference for the return trip.
A simultaneity shift, as you call it, is just a change of simultaneity convention. Nothing physical happens to your twin's clock. It's not a physical change to anything.
 
  • #5
tagehedin said:
When I turn around my plane of simultaneity shift and I see my twins clock run fast
These two things have nothing to do with each other.

The "simultaneity shift" is purely a convention that depends on how you choose your coordinates. No physics depends on it.

What you actually see of the other twin's clock is an invariant, independent of how you choose your coordinates: it is the result of the relativistic Doppler effect. When you turn around, you change the relativistic Doppler effect that you observe in the light signals reaching you from the stay-at-home twin.

More here:

https://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_doppler.html

tagehedin said:
Do I see the light-ray of his clock bouncing faster than the speed of light between the mirrors or do I see his clock contract so that the light-ray can bounce quicker in the shorter space?
No.

I suggest looking at the actual math of the relativistic Doppler effect.
 
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FAQ: Light clock running faster than light?

What is a light clock?

A light clock is a hypothetical device used to illustrate the principles of special relativity. It consists of two mirrors facing each other, with a beam of light bouncing between them. The time it takes for the light to travel from one mirror to the other and back is used to measure time intervals.

Can a light clock actually run faster than the speed of light?

No, according to the principles of relativity, nothing can travel faster than the speed of light in a vacuum. The concept of a light clock running faster than light contradicts the fundamental laws of physics as we understand them.

What happens to a light clock at relativistic speeds?

As a light clock approaches relativistic speeds (close to the speed of light), time dilation occurs. This means that time appears to slow down for the light clock when observed from a stationary frame of reference. The light clock itself does not run faster; instead, time for the clock appears to move slower relative to an outside observer.

How does time dilation affect the operation of a light clock?

Time dilation causes the light clock to tick slower as it moves at high speeds. For an observer moving with the light clock, time appears normal, but for a stationary observer, the light clock's ticks are spaced further apart. This is a direct consequence of the invariance of the speed of light and the principles of special relativity.

Is it possible to observe a light clock running faster than light in any reference frame?

No, it is not possible to observe a light clock running faster than light in any reference frame. The speed of light is the ultimate speed limit in the universe, and all physical laws, including the operation of a light clock, are consistent with this limit. Any observation suggesting otherwise would violate the principles of special relativity.

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