"Peri of Pera" wrote in message ...
The Measurement of Contraction

[snip]

But let us ask questions about such a measurement. Event 1 is the
recording of location A of one end of a rod in space at time t by
observers S and S'.

This is wrong already.
First you decide in whose coordinate system the rod is
at rest. Let's assume that this is S. So for S' the rod is
moving, so S' must make sure he measures the events
simultaneously - otherwise he is just daft.

Event1 is something that happens on one end of a rod
at time t1' according to observer S'.
According to observer S who is at rest w.r.t. the rod,
this happens at some time t1.
According to S' the spatial coordinate of this event is x1'.
According to S the spatial coordinate of this event is x1

Event 2 is the recording of location B of the
other end of the rod also at time t by the same observers.

Wrong again
Event2 is something that happens on the other end of the rod
at the same time t2' = t1' according to the same observer S'.
According to observer S who is at rest w.r.t. the rod,
this happens at some time t2.
According to S' the spatial coordinate of this event is x2'.
According to S the spatial coordinate of this event is x2

If S' is to measure the lenght of the rod, he must make sure that
t1' = t2' ,
so he can *DEFINE* the "coordinate length" as
L' = | x1' - x2' |

For S the times t1 and t2 don't matter since he is at rest
w.r.t. the rod, so he *DEFINES* the "proper length" as
L = | x1 - x2 |

The
experimenter picks up and analyses the four space time co-ordinates
made by the two observers.

I have counted 8 space time co-ordinates, two of which must
be identical: t1' = t2'.

Will the answer be the contracted length of
the rod? How will the movement of the two observers relative to the
rod disclose the contracted length of the rod and not a distorted view
of it?

If you do it correctly, you will get
L' = L / gamma
which says that the coordinate lenght is contracted w.r.t. to
the proper length.

How are optical, communicative and angular aspects included in
the measurement?

For both observers the times and the distance of events
are recorded by sending light signals to the events. This
has been explained to you before. See if you can find
how it is done.
In the one dimensional case there are no angles involved.

What single fixed co-ordinate system is common to
both observers

none.

or is it only relative to observer S or observer S'?
How will the experimenter establish that the times t of the two
observers are simultaneous given that SR imposes a whole set of ifs
and buts on simultaneity?

See above.

How will any difference in the speed the
observed object, S and S' be taken into account?

See above.


It all can be done on paper making assumptions but not as a real test.

Indeed, this particular test never has been done.
We also never dropped you from a high tower to test whether
you will indeed fall.

The more ardent supporters of the contraction hypothesis assert that
proof is not required.

I don't think that you need a proof for your falling down
from a high tower either.

Their argument is that to 'make predictions' is
sufficient or they will do the calculations manually and if these are
rejected or ignored by anyone,

They should also be consistent with all other experiments
which *have* been conducted (and which, by the way, are generally
ignored by most people on this forum)

they accuse him of being incapable of
the maths and he should study the subject to understand the theory.
With understanding they mean accepting it without reservation. It is
the approach of all monotheistic religions which ostracise all non-
believers, excommunicate them, vilify them, and ultimately stone or
burn them. In this NG it is automatically practised against any member
who dares to reject SR or even question it.

No, rest assured, on this NG these people are not stoned or burned.
We just have a good laugh over them, and we use them for practice
for when we have to explain to our kids. Thanks for that. It has worked
superbly!

Dirk Vdm