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

The theory of relativity is presented as one that cannot be understood
by most people.

Not 'cannot', just 'is difficult'

This aura of complexity and difficulty is maintained
by using ambiguity and vagueness in describing and defining the theory

No .. the theory is very clear and precise .. however, some popularisation
of it are vague and ambiguous, because they use colloquial terms that the
layman is more familiar with, and those terms are vague and ambiguous.

and defending it with even more ambiguity and vagueness against logic.

There is nothing illogical about SR

But what is it really? Stripped of all esoteric language it simply
means that physical objects (we may call them frames) that are capable
of motion (cars, trains, planes, the earth, planets, stars) will
shrink along the axis parallel to the motion and have their clocks
slow down.

No .. nothing happens to the object .. it can't do. Someone moving quickly
past you does not change you. But something happens to how they are
measured by things that move relative to them

The effects are in proportion to the velocity of the object

No .. they are not in propoertion at all.

and are called length contraction and time dilation.

You missed relativity or simultaneity .. so many people do, yet it is
probably the most important effect

They can be
calculated using the transformation formulas that are the substance of
the Lorentz contraction hypothesis.

Why not just say "Lorentx transforms"

But as the tools of measurement
(rulers, clocks) are also adjusted relative to the speed,

Now you are talking LET, not SR. LET is the one that claim physical
shrinking and an absolute frame of reference and aboslute velocities etc
(its a bit like what KenSteo talks about, only LET is self-consistent)

any change
in metres and clock rates will not be noticed by anyone measuring
length or time in his environment (the local frame). Regardless of the
velocity of the local frame, things measured within the local frame by
local frame occupants always have the same size and the local frame
time always flows at the same rate.

Again, the above is not SR

However, the supporters of the relativity theories (both SR and LET)
have introduced the concepts of observed frame and observer frame.

Well, derr .. there isn't much physics able to be done if there is no
observer !!

If
an observed frame and an observer frame travel at different speeds, it
is claimed that any contraction and dilation affecting the observed
object can be measured by an observer in the observer frame.

There is no contraction and dilation in the observed object in SR .. there
is only a measurement of it from the observer frame.

A
procedure of measurement which will lead to 'the visibility of
contraction' is described in a textbook (Resnick, Introduction to
Special Relativity, 1968) as:

"An observer is an INFINITE set of recording clocks distributed
throughout space, AT REST and synchronized with respect to one
another. The space time co-ordinates of an event (x,y,z,t) are
recorded by the clock at the location (x,y,z) of the event at the time
(t) it occurs. Measurements thus recorded throughout space time (we
might call them local measurements) are then available to be PICKED UP
and ANALYSED by an EXPERIMENTER who collects the measurements made in
this way. Each inertial frame is IMAGINED to have such a set of
recording clocks, or such an observer. The relations between the space-
time co-ordinates of a physical event measured by one OBSERVER (S) and
the space-time co-ordinates of the same physical event measured by
another OBSERVER (S') are the equations of transformation".

Resnick uses the terms INFINITE, AT REST, PICKED UP, ANALYSED,
EXPERIMENTER, OBSERVER (S) and OBSERVER (S').

So?

While the phraseology
may not prevent calculating contraction according to the Lorentz
formulas with a pencil on a piece of paper, it can surely never be
done in the field.

We measure and calculate the positions, speeds, and lengths of moving
objects all the time .. what are you alking about?

It is a smokescreen to support the illusion that
contraction is a physical reality.

It isn't in SR. In LET it is a physical reality that we cannot measure
(which is rather pointless)

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'. Event 2 is the recording of location B of the
other end of the rod also at time t by the same observers.

Yes .. that is what length is. The thing is, time t for S and time t for S'
are not simultaneous

The
experimenter picks up and analyses the four space time co-ordinates
made by the two observers. Will the answer be the contracted length of
the rod?

The rod isn't contracted (in SR) .. but he will see possible different
measured lengths by the two observers, depending on the relative velocities
of them compare to the rod. In LET the situation is the same, excpe that
the rod is said to possibly be contracted due to its absolute motion in the
ether, but what the observers observe is the same in either case.

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?

There is no contracted length in SR, and it won't disclose the contracted
lenth in LET (you cannot determine what the contracted length is in LET)

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

When we talk about what we the length of the rod is for the two observers to
be here, we make adjustments for those things .. ie it is what we measure
after tkaing into account the possible differences in transit time for
light, aberation etc etc..

What single fixed co-ordinate system is common to
both observers or is it only relative to observer S or observer S'?

It is relative. In LET there is an unknown absolute ether system of
coordinates, but that doesn't really make any difference.

How will the experimenter establish that the times t of the two
observers are simultaneous

They aren't

given that SR imposes a whole set of ifs
and buts on simultaneity? How will any difference in the speed the
observed object, S and S' be taken into account?

In what way 'taken into account' .. the observers measure what they measure.
If you want to do some calculation using Lorentx transforms back to the
frame of the rod itself, then you get that the rod is the length of the rod
... but what I assume you are actually interested in is the length of the rod
in the frames S and S' .. ite how much space the rod takes up at a given
time in those two frames respectively

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

No .. it can be done as a real test.

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

We have experiments that indicate length contraction. It is more difficult
to measure as we need to get something up to very high speeds and measure
its length .. and that is tricky to do.

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 accuse him of being incapable of
the maths and he should study the subject to understand the theory.

Noone argues that.

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.

Nonsense