Re: Question about light clock - Part II


"The Ghost In The Machine" <ewill@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:ddl6q2-kcl.ln1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> In sci.physics.relativity, sue jahn
> <susysewnshow@xxxxxxxxxxxx>
> wrote
> on Sat, 9 Jul 2005 23:21:02 -0400
> <42d099be$0$18642$14726298@xxxxxxxxxxxxxxx>:
> >
> > "The Ghost In The Machine" <ewill@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:8rc6q2-jdk.ln1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> In sci.physics.relativity, sue jahn
> >> <susysewnshow@xxxxxxxxxxxx>
> >> wrote
> >> on Sat, 9 Jul 2005 14:48:08 -0400
> >> <42d0212d$0$18637$14726298@xxxxxxxxxxxxxxx>:
> >> >
> >> > "The Ghost In The Machine" <ewill@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> > news:5mh5q2-00i.ln1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> >> In sci.physics.relativity, john_doe_ph_d@xxxxxxxxx
> >> >> <john_doe_ph_d@xxxxxxxxx>
> >> >> wrote
> >> >> on 9 Jul 2005 09:30:40 -0700
> >> >> <1120926639.984191.137670@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>:
> >> >> > Let's say there's a mechanism on a platform that shoots a ball
> >> >> > vertically upward. The ball then comes down and lands on the mechanism.
> >> >> > If the platform is now moving with a uniform speed in the horizontal
> >> >> > direction and the experiment is repeated, to an observer on the
> >> >> > platform the ball would still shoot straight up and come straight down
> >> >> > again (ignoring air resistance). The explanation of this is that the
> >> >> > ball starts out with (and always has) the same horizontal speed that
> >> >> > the platform does, so it keeps up with the mechanism as it moves along.
> >> >> >
> >> >> > Now let's consider a platform with a vertical light clock with a source
> >> >> > below and mirror above. When at rest, the light strikes the mirror and
> >> >> > comes back down to the source, traveling vertically at all times. Now
> >> >> > let's move the platform horizontally at a uniform speed. The whole
> >> >> > platform could be enclosed so that, as far as an observer on the
> >> >> > platform is concerned, he doesn't know he is moving. Of course, the
> >> >> > light would again strike the mirror and come back down to the source
> >> >> > (or else the observer would have an experiment that could tell him if
> >> >> > he is at rest or moving with a uniform speed).
> >> >> >
> >> >> > My question is: what is the physical mechanism that is keeping the
> >> >> > light vertical when the platform is moving? Since light is massless, I
> >> >> > don't think it makes sense to say that it has the initial horizontal
> >> >> > speed of the platform, as we did above for the ball.
> >> >> >
> >> >>
> >> >> The light is not vertical, as observed by the stationary observer.
> >> >> It describes the hypotenuse of a triangle.
> >> >
> >> > How does the light know a stationary observer is looking at it?
> >> > What if we blind fold the stationary observer ?
> >>
> >> It doesn't. Light doesn't care about verticality. It merely is.
> >>
> >> We write field equations, and hope they're correct.
> >
> > Well.... ahhh can ya hope faster ? :o)
> >
> > The way to understand what a light clock is supposed
> > to do is to 'build' the sonar equivalent and pull it behind
> > a boat. The ticking rate should slow with motion the same
> > regardless of orientation if the math is right.
>
> Wrong.
>
> The rate of slowing is independent of the math. If the math
> is right it correctly predicts the slowing. If the math
> is wrong ... well, the math is wrong; the clock couldn't
> care less; it just slows.

I worded that poorly. You aparently did not see the quotes
around the word 'build'. LOL

I can 'build' an airplane flying circles in a constant wind
that some will claim borrows northbound time and repays
southbound time. 'building' the correct vector analysis
shows otherwise. All 'built' on paper.

>
> >
> > Then you graduate to light clocks and decide if you are
> > modeling ether, dielectrics or squash courts and whether
> > an observers gaze can alter the operation. ;-) When
> > you're all done you can compare it to Einstein's
> > clock that *goes* as it is *judged*
> > http://www.bartleby.com/173/23.html
> > and understand why the anomalous twin is because
> > the light clock isn't an exact substitute. A light clock
> > isnt't reversable, a variable path is.
>
> Not sure what it means to have a light clock reversible.
> The revsibility of physical phenomena is primarily in the
> realm of thermodynamics, AFAICT.

If your clock changes rate because you run to and fro
while watching it, the ticks are borrowed and repaid.
That is what I meant by reversable.

A light clock can't speed up to repay the ticks, so
the lost ticks, are forever lost. It probably does have
some thermodynamc application but I don't know
just what it is.

Sue...

>
> >
> > Sue...
> >
> > From Lorenz to Coulomb and other explicit gauge transformations
> > J. D. Jackson
> > Department of Physics and Lawrence Berkeley National Laboratory
> >
> > E. Technical remark
> > There is a technical point here. Our development of the v-gauge
> > potentials is based on an arbitrary speed of propagation for the
> > scalar potential, either slower or faster than the speed of
> > light, but did not envision an imaginary speed. That is what
> > happens for = c2/v2 negative. Weber's vector potential requires
> > = -1. Happily, one can show that there are no problems in
> > the quasi-static limit. But detailed consideration of this regime,
> > with its exponentially growing or decaying instead of propagating
> > solutions, would take us too far afield to pursue further here.
> > Baxter18points out that v must be real in QED, but a negative v
> > is permitted.
> > 18 C. Baxter, " -Lorentz gauge QED," Ann. Phys. 206, 221-236 (1991).
> > http://arxiv.org/abs/physics/0204034
>
> I'm not entirely certain what can be done with imaginary velocities
> (or, more properly, with velocities whose components are in C as
> opposed to R).
>
> >
> >>
> >> >
> >> > Sue...
> >> >
> >> >>
> >> >> Because of the Lorentz distortions, however, lightspeed is still
> >> >> measured as c.
> >> >>
> >> >> Instead of a vertically-oriented TWLS you might want to consider
> >> >> something more along the lines of the Michelson-Morley experiment.
> >> >>
> >> >> --
> >> >> #191, ewill3@xxxxxxxxxxxxx
> >> >> It's still legal to go .sigless.
> >> >
> >> >
> >>
> >>
> >> --
> >> #191, ewill3@xxxxxxxxxxxxx
> >> It's still legal to go .sigless.
> >
> >
>
>
> --
> #191, ewill3@xxxxxxxxxxxxx
> It's still legal to go .sigless.


.