21 Aug 2005 [To Steuard Jensen]

Thank you for the kind and timely response. And the endorsing manner.

[...]

So now, if I may impose a little further...

Your confirmation of my suspicions leads me to a problem with the  
"light clock" that is often used in the explanations of relativity.

If the emission of light is an event that has specific space-time  
coordinates independent of the motion/velocity of the emitter, then...

1.    Let's assume (if we can) that the light pulse from the light  
clock is a laser beam a mere one photon wide.

2.    Let's further assume that the beam is exactly perpendicular to  
the direction of travel of the source of the beam (the base of the  
light clock, I suppose).

3.    And let's further assume that the reflecting mirror at the top  
of the light clock is very, very, very tiny.

4.    THEN...If the light clock is not in motion relative to the time/ 
space coordinates of the event of the pulse, the photon will go up to  
the mirror at the top and bounce back to the receptor at the bottom  
of the light clock. And we can measure the elapsed time.

5.    HOWEVER, if the light clock is moving fast enough relative to  
the time/space coordinates of the pulse event, it seems to me that  
the photon will miss the mirror at the top because the mirror will no  
longer be perpendicular to the event coordinates by the time the  
photon reaches the top of the light clock.

If my presumption is true, then I do not understand the light clock  
diagrams that show the diagonal path of the light when the light  
clock itself is moving rapidly through space.


Any help you can give me on this sticking point will be greatly  
appreciated.