Re: Question about light clock and derivation of time dilation

[This thread has lots of argument but no insight at all on the basic question....]


john_doe_ph_d@xxxxxxxxx wrote: 
Time dilation is typically the first SR effect derived in text books,
and it is usually done with the example of a light clock as follows,
[...] but I am trying to reconcile B's observation of the light path
with the fact that the light source is pointed in the vertical
direction. Doesn't that tell B that the light is "really" just moving
up and down? Wouldn't B have to see the light source tilted to make
sense of his observation of the light path?

In A's frame, the light source is pointed vertically, and the light goes up and reflects back down along the same path. In particular, the light hits the mirror at a specific point.

Viewed from B's frame, the light must hit that exact same point on the mirror, but during the time the light went from source to mirror the mirror moved horizontally, so the path of the light MUST be diagonal in B's frame. To B the light source itself is not tilted, but the path of the light inside the source certainly is -- that's just a smaller version of the same situation.

Every directional light source we have consists of basically two parts: an omnidirectional light emitter and a collimating system to impose directionality. Between these two parts, the light that gets out of the source travels vertically to A and diagonally to B; both must see the light emerge from the same point of the aperture of the collimating part of the source.

Adding a fiber optic between source and mirror does nothing to resolve this issue -- you must look INSIDE the light source.


from a conceptual point of view, I am
asking how B reconciles a tilted light path with a vertical flashlight.

To B, the omindirectional emitter and the collimator are arranged vertically (as as they are to A). But to B for light to get out of the collimator it must travel diagonally inside the light source.


Tom Roberts	tjroberts@xxxxxxxxxx
.

Relevant Pages

  • Re: Question about light clock and derivation of time dilation
    ... the invariance of the interval and time dilation can all be ... The papers rather inspired me to write a Mathematica notebook that derives ... but I am trying to reconcile B's observation of the light path ... Wouldn't B have to see the light source tilted to make ...
    (sci.physics.relativity)
  • Re: The relativity of simultaneity
    ... do that without bringing up "light path lengths" and "absolute ... Seto's "alternate explanation": RoS is wrong because if 2 events are ... this thread, Seto. ... light from the light source to reach M before it reaches M'. ...
    (sci.physics.relativity)
  • Re: Question about light clock and derivation of time dilation
    ... > moving horizontally w.r.t. the clock, the light is taking a longer path ... but I am trying to reconcile B's observation of the light path ... Doesn't that tell B that the light is "really" just moving ... Wouldn't B have to see the light source tilted to make ...
    (sci.physics.relativity)
  • Question about light clock and derivation of time dilation
    ... moving horizontally w.r.t. the clock, the light is taking a longer path ... but I am trying to reconcile B's observation of the light path ... Doesn't that tell B that the light is "really" just moving ... Wouldn't B have to see the light source tilted to make ...
    (sci.physics.relativity)
  • Re: Lux with plain reflector?
    ... What would the reading be if the ceiling is replaced by a perfectly reflecting ... The mirror is doubling ... between the light source and the mirror, so in a theoretical universe, ... to the extent that radiosity software generally ...
    (sci.engr.lighting)