Natural Science Forum / Physics / Relativity / July 2005

Actually, for the purposes of making the math simple I arbitraily
defined the speed of light to be 300,000,000 meters per second.  The
1000 ticks that you mention above is not arbitrary.  I also defined
that the master oscillator had a frequency of 300,000,000 cycles per
second.  That number was chosen to make a single *tick* of the
oscillator to equate to light traveling the distance of 1 meter.

Understood, but irrelevan as a thought experiment.

It is important to understand that the ONLY significance of the LENGTH
of the fiber optic cable is the distance that it will allow you to get
between the end of the cable and the receiving lens. For the
experiment I described for you, the cable could be 5000 meters long.
As long as you follow the described calibration procedure and move the
end of the cable 1000 meters from the receiving lens the results will
be exactly the same.

Understood.

It is important to understand that there is only ONE *clock* in the
device.  It is the only timing element.  The two counters only count
the output pulses of the oscillator.

Understood. But that not what you wrote previously. I quote: " Light
speeds down the 1000 meters of cable, while the first counter ticks
away". Now, according to what u r saying, the counter does not tick; it
reads or counts the "pulses" from the oscillator (main clock).
"ticking" refers to an object that keep time, a clock. "counter" refers
to an object that reads or counts  or notes whant is indicated on a
clock.
But the two counters can be considered as clocks too, that tick at the
same rate as the main oscillator, which is a clock also. But this is
also irrelevent. Only one clock is needed as you say, and the counters
are superflous here.

You should probably read my replys and re-read the setup.  Your
conclusion is in error.
Well, at least you are consistant in your misunderstanding.

I will look at the other posts.

Now, here is the experiment simplified. Tell me if this is equivalent
to the experiment u have in mind:

At location X we have a clock and two counters that notes time from the
clock. To the clock is attached both ends of a 1000 m (fibre,empty
space) cable. (this cable can be looped around or just flat on the
ground or whatever).

The calibration: The clock sends out a light pulse in the "first" end
of the cable. This pulse travels within the cable to reach the other
end where it rejoins the clock. This clock (or even the counter if you
wish), notes the total time of travel, wich is, according to SR, T1 =
1000/c. (this is what both clock and counter indicate...if the counters
are cosidered as clocks too).

The experiment: Detach the second end of the cable from the clock and
set this end 1000m away from the clock.
Fire a pulse of light in the attached end of the cable and "start" the
clock and first counter. As the light pulse reaches the free end, the
clock (and the first counter) thus indicate T1. At this instant,
counter 1 signals to counter 2 to start counting the time elapsed on
the clock. Also at this instant, the light pulse emmenating from the
free end of the fiber is reflected back towards the clock. It takes a
time of T2=1000/c for the pulse to reach back to the clock, the instant
when counter 2 stops. Hence the clock indicates 1000/c + 1000/c and
counter 2 indicates 1000/c.

So the counclusion, using SR, is that counter 2 indicates 1000/c.
The conclusion, using PFT, although the algebra is completely
different, yields the same conclusion.

Is this experiment equivalent?

The assumption you are making is one of spatial isotropy/homogeneity which
is one of the assumptions aether theories can violate and still be in accord
with observation eg in LET we have an aether wind that breaks isotropy but
is never actually detectable.

That is - common sense.  And no one doubts from common sense it is the same
speed in both directions - proving so is another matter.

I know many posters to this group would be particularly interested in any
concrete experimental way to prove a frames spatial homogeneity/isotropy ie
proof similar to Brownian motion proving the existence of atoms.  It is the
denial that such proof can in principle be found that the claim you can not
show OWLS is always constant is based on.  And indeed it is obvious it must
be so because to measure OWLS you must have some way of syncing the clocks
at each end and such syncing is purely a matter of convention - which is the
basis of the claim that it is trivially obvious it is not possible to
experimentally show OWLS is the same.  For example if you choose light as
your syncing method then of course OWLS is always constant by fiat.  If you
choose say firing bullets from a gun then you need to show that the time it
takes for the bullet to traverse a certain distance does not depend of where
or in what direction the experiment is done - for which you need synced
cocks at the start and end points.  Indeed to show a frame is inertial under
the usual definition of free particles move at constant velocity you need
synced clocks to show particles behave that way.  There is simply no way to
get around the clock syncing issue.  Theoretically we can assume an inertial
frame is isotropic is which case OWLS constancy follows immediately from
TWLS constancy - but showing such a frame is isotropic/homogeneous
experimentally is simply not possible.

Bill

I hate to have to be the one to point this out to you Tom, the light
only travels ONE WAY in the fiber optic cable.  Also, just for the
record, for the orientation of the cable to have any effect on the
velocity of light within the cable, would have to presume that
experimental evidence showing that the velocity of light is constant
and relative to the medium, not to be confused with a vacuum, is in
error.  If you could provide some insight as to why you believe this
it would be useful in understanding your insistance that this is a two
way measurement.

       "The lack of reason is overcome by the passion of belief"
                           < cj@totcon.com >

We are comparing the speed of light in two very different media. It is
unlikely that something will effect BOTH speeds by the same amount.

scope
laser--------fiber---------------------------------\
diode.............................................-/
East                                                West
length fiber is constant. distance diode-fiber is variable.
deltat = c1 * delta distance - (cw * lw + ce * le)
but lc (length of cable) = lw (length to the west + le (length to the east)

deltat = c1 * delta distance - ce le + cw(le -lc)
if ce = cw
deltat = c1 * delta distance - cw lc
if cw is constant
deltat = c1 * delta distance - a constant.

I don't really care very much. If it appears to be constant, I will be happy.

You perform the test with your cable moved outward in many different
directions.

If you find that the delta delay is only dependent on distance between photo
diode and the end of the cable, then it doesn't matter that part of your
apparatus is has the signal traveling two ways, the ONLY part where the
testing of light [in a vacuum] is taking place is between the end of the
fiber and the photo diode. Everything else remains 'constant' and drops out
of any calculations.