# An atomic clock and a normal clock

Galileo Galilei
Two clocks in a spaceship floating though space at 99% the speed of light. One is a atomic clock and uses light and mirrors to measure time, the other clock uses cogs and gears like a conventional clock. From the perspective from inside the ship both clocks tick and tock at the usual rate, however from the perspective of a observer that experiences the ship travel by only the atomic almost stops yet the mechanical clock keeps ticking? Basically are mechanical clocks effected with exactly the same conditions as atomic clocks or do the laws of physics differentiate between the two?

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Dale
Mentor
Both clocks slow down. This is required by the first postulate of relativity.

jtbell
Mentor
Note that you can make the spaceship and clocks travel at 99% of the speed of light either by accelerating the spaceship (firing its engines), in which case the acceleration can have different effects on different kinds of real clocks; or by accelerating yourself while the spaceship simply keeps on "doing its own thing," in which case it is hard to imagine how the operation of different kinds of clocks (whether real or ideal) could be affected differently.

Galileo Galilei
I can see why they would behave the same, the atomic clock is slowed down because its limeted by the universal constant of light but in the case of a macanical clock i think that the rate in the electric in the clock travels will also be inhibated slightly which would cause the macanical clock to slow down preportionatly to the atomic clock, would you agree?

Galileo Galilei
Basically the curcuits of a digital clock would run slower and the batterys of a conventional clock would chuck out less power, this would depend on electric being restricted to the speed of light also.

A.T.
in which case it is hard to imagine how the operation of different kinds of clocks (whether real or ideal) could be affected differently
It would lead to paradoxes, if the rate ratio of two clocks placed next to each-other at relative rest would depend on the observer.

ghwellsjr
Gold Member
Two clocks in a spaceship floating though space at 99% the speed of light. One is a atomic clock and uses light and mirrors to measure time, the other clock uses cogs and gears like a conventional clock. From the perspective from inside the ship both clocks tick and tock at the usual rate,
I presume that when you say "from the perspective" you mean that both clocks have some kind of display on them that an observer inside the ship can watch and see that they are ticking at the same rate. In other words, if he sees at one moment in time that they are displaying the same time, then any time later he can see that they continue to display the same time. This means, of course, that the light coming from both displays takes the same amount of time to reach his eyes, correct?

however from the perspective of a observer that experiences the ship travel by only the atomic almost stops yet the mechanical clock keeps ticking?
I presume again that when you say "from the perspective", you mean that this second observer sees the two clocks traveling at some high speed away from him. But why do you think the light coming from their two displays would present different images to his eyes?

Basically are mechanical clocks effected with exactly the same conditions as atomic clocks or do the laws of physics differentiate between the two?
How is this question related to your scenario? I don't see the connection. Please explain.

Dale
Mentor
I can see why they would behave the same, the atomic clock is slowed down because its limeted by the universal constant of light but in the case of a macanical clock i think that the rate in the electric in the clock travels will also be inhibated slightly which would cause the macanical clock to slow down preportionatly to the atomic clock, would you agree?
If I understand correctly your point then yes I agree. Also, all wind up or other similar clocks also use EM interactions at a basic level.

jambaugh