Re: "The Making of Observations in Relativistic Systems"
- From: surrealistic-dream@xxxxxxxxxxx
- Date: 14 Nov 2005 10:22:52 -0800
Cdr wrote:
> "The Making of Observations in Relativistic Systems"
>
....
> In 1905 Dr. Einstein derived Special
> Relativity using mathematics applied to accepted physical laws.
This is not correct. In 1905, physicists lived with a schiziod notion
of what a "physical law" meant: On the one hand was the traditional
meaning of a Galilean-covariant law, which had the same form for all
inertial frames of reference, and on the other hand was the Lorentz
interpretation of the laws of E&M being true only in the very special
rest frame of the ether. The former interpretation of physical laws
could be called the "traditinal values" of what physical laws meant.
Ironically, E&M, interpreted mechanically, seemed to propose a
tremendous challenge to the harmony of physical laws: Einstein asked
himself if there could not be found a single principle which could be
used to harmonized the notions of the laws of mechanics and the laws of
Maxwell's equations. He found that there is! He re-organized Lorentz's
E&M so that the Galilean-Newtonian PoR could be extended to include
both mechanical and E&M phenomena: The laws of both mechanics and E&M
will present themselves to us in a Lorentz-covariant form. This was
used as a heuristic in practice, with the condition that the laws of
the new theory for the motion a point-mass particle will reduce to
those of Newton when v << c.)
> When one examines the atomic clock experiment one must decide
> between one of two interpretations. One must consider the possibility of
> whether
> that velocity of the trip caused the moving clock to speed up during one
> part of
> its trip around the world and to slow up on the part so that the total
> elapsed
> time was consistent with the observation. The other interpretation was that
> the
> velocity made the rate of passage of time itself change due to its movement
> through space-time. In order to distinguish between the possibilities, it is
> necessary only necessary to consider the effects of a change in reference
> frame
> occurring when the observations are made and these observations are made at
> the
> same location and at the same velocity reference and, as a result, we must
> conclude that it was not time which slowed during the trip, it was the speed
> of
> the clock. (This conclusion may be made easier to accept when one recognizes
> that the experiment could have been set up, in principle, in a form akin the
> auto speed tests on the Bonneville Salt Flats in which the clock travels at
> a
> constant rate of speed and in a straight line in one direction and then is
> stopped and reversed indirection and returns to its starting point along the
> same straight line. All of the measurements would be made by identical
> clocks
> with the time required to turn the vehicle around subtracted from the time
> difference.
Why? The clock "at rest" still ticks away during this turn around. I
can see you subtracting off this time interval on both clocks if you
want to determine \gamma from the data.
> Spacetime is not involved in this analysis.) Since all of the
> measurements of the actual experiment were made at the same location and
> velocity reference frame, the actual elapsed time must have been the same
> for
> both clocks one must conclude that it was the moving clock that slowed its
> speed
> and not a reduction of the actual passage of time.
Let me see if I have your thought experiment down right (a simplified
version, anyway): You want two clocks, A and B, initially synchronized:
Clock A is at some fixed point in a frame S, which is rigidly attached
to the earth's surface. And the other, clock, B, is fixed inside a car
that will drive around in S, starting from the same position that clock
A holds, and then it returns after a long time to the starting point
where clock A has remained. So, you want to see if clock B is behind
clock A (admittedly, this is a bit simpler experiment than you setup).
This is doable. But having enough fuel for the car so that the
experiment can run long enough for the effect to be measurable is the
question. Maybe the car will have to come to a stop and get refueled
many times before the experiment is concluded. Obviously, we will
ignore the non-inertiality of frame S to begin with.
When you say that "Spacetime is not involved in this analysis," you
make me believe that you haven't any idea what spacetime is. You might
as well say that one is better off making a long cross-country trip
without the use of a map. Or say that, One shouldn't draw free-body
diagrams in Newtonian mechanics, because they convolute things. Or say,
I prefer not messing-up classical mechanics with phase space, which
might interfer with the measured values. Or you might as say tell an
engineer not to use flow charts, as they could interfere with the
equipment. It's just ignorant. Spacetime is just an analytical aid. The
analytical tool used does not change the experiment.
Free-body diagrams, phase space, maps, flow charts, and spacetime are
all merely analytic aids. Period.
>
> The physicists assertion that "time is what clocks measure" is
> naive. "Time is what clocks measure after the assumed speed of the clock has
> been corrected for the change in size of the units of measurement for time
> resulting from velocity". (In other words, changing the velocity of the
> clock
Of course! It's the theory one operates under that tells you
(interprets for you) what you are observing. The same is true for
people who believe in absolute time. The phrase "time is what clocks
measure" is an operationalist viewpoint. One can formulate some other
viewpoint, however, one must still relate theoretic time to simple
clock readings somehow.
.
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