>Whether you deal with SRT as
>Einstein did in his 1905 paper or as Minkowski did in terms of
>space-time, the Lorentz transformation eqns are the same. It doesn't
>matter whether you call t a parameter or a coordinate, t = constant
>isn't the same as t' = constant. Lorentz had a preferred frame, the
>aether, so that the transformation eqns would hold between the aether
>frame & any moving frame but not between 2 arbitrary inertial frames.
>Thus the transformations between intertial frames wouldn't form a group.
>(&, of course, no one has found the aether!)
> You can choose an arbitrary frame & call it "preferred" - but
>why? As I noted, the Incarnation makes it possible to speak
>meaningfully of "God's rest frame".
It has been suggested that we can use the measureed anisotropy of the
microwave background radiation to determine the privileged reference frame:
"At any given place in teh universe, there is only one reference frame in
which the universe expands isotropically. This privileged reference frame
defines a privileged time scale (the time as told by a clock at rest in
that frame)" (P.C.W. Davies, "Space-Time Singularities in Cosmology and
Black Hole Evaporations," in Fraser, Lawrence and Park, eds, _The Study of
Time III_, p. 76). Davies goes on to note that "Happily, the earth is
moving very slowly [approx. 360 km/sec is the figure I have seen-GD]
relative to the local privileged reference frame in our vicinity of the
universe, so that Earth time is a fairly accurate measure of cosmic time."
> Einstein moved away from positivism, & by 1920 called Mach "a
>good mechanic but a poor philosopher". When he was asked near the end
>of his life to contribute to the Carnap _Festschrift_ he declined with
>some rather sarcastic remarks about positivism.
Though Einstein did move away from Machian positivism later in his life, he
never moved away from the operationalism which his early positivist
epistemology forced on him. His definitions of time and simultaneity were
operatialist throughout his life. But to say that "Time is what we measure
with a clock" is not to give an answer to the question "What is time?"
>> Under some models of GTR, including the class of "physically realistic"
>> solutions, a privileged reference frame is possible.
> At any space-time event you still have the freedom of local
>Lorentz transformations. The Friedman-Lemaitre models have a "cosmic
>time", but the description of the model by an observer moving with
>respect to the "privileged" observers is still valid.
>> Even if we cannot do
>> better than an operationalist notion of physical time, we still are not
>> forced to give up the idea of absolute simultaneity.
> We are unless we can keep people from moving.
:^) Even if people persist in moving relativistically, it seems that we
only are forced to give up our knowledge of simultaneity, not the thing