On Fri, 29 Dec 2006 20:07:28 -0000, "George Dishman"
wrote:


"Lester Zick" wrote in message
.. .
On 29 Dec 2006 03:54:29 -0800, "George Dishman"
wrote:

Repeating my previous reply of the 24th in reply to your
copy in the original thread:

Once more unto the google breach I fear, George. No idea why your
previous reply never showed up on the original thread.

What a pain. I'm going to have to raise a ticket
with them, this is getting beyond a joke.

I agree. But why not just change news servers?

Didn't press
because of the holidays. Just out of curiosity is this post showing up
on the new thread or am I still stuck on the old?

This is in the new thread, only the content was copied
from the old. You should be able to use this link to
see your message to which I replied:

Thanks but I have a copy collated and saved under the new thread.
Still seems like a mystery to me. At least here Jeff and Gurcharn
should be able to keep abreast of the conversation more easily.

"Lester Zick" wrote in message
...

George


~v~~

Lester, George,

I haven't yet finished writing replies to some posts in
the earlier thread from more than a week before Christmas,
but there are a couple of things I want to say right now.

First, my offer to Lester of $9,000 to show that there is
a contradiction in special relativity is still open until
the end of the year, my time. I'm willing to extend that
deadline if you request it. You may not have taken my
offer seriously, and the whole purpose of the offer is to
motivate you to take seriously the business of supporting
your assertions. You have since repeated numerous times
the assertion that there is a contradiction, but have not
supported that assertion with any evidence or even an
argument.

I'm willing to extend the deadline because I didn't get
back to you when I should have, after your first reply.
If you disbelieve that I would judge your argument fairly,
we can find a neutral judge.

As George has pointed out, your objection is actually
against your own interpretation of Lorentz's aether theory
rather than against SR, so you may need the extra time to
define what it is you are trying to show.

* * * *

George Dishman replied to Lester Zick December 22, 2006:

SR explains that change of length not as a physical
contraction (like thermal changes) but as a rotation
in the x-t plane due to the relative motion.

I don't know what the latter means ..

That is the one area that is at the root of all our
disagreements.

One of several areas, and not the most fundamental.

But I don't consider it essential to SR that the effect
of relative motion be thought of as a "rotation". While
that is an accurate and insightful description of what
happens, it is rarely described that way in popular books
and articles on relativity, perhaps because it is easily
misunderstood. On the other hand, if it is described as
a rotation in "Spacetime Physics" by Taylor and Wheeler,
I will have to agree that it is the way to go, even if it
requires a bit more effort.

Is that how "Spacetime Physics" describes it?

-- Jeff, in Minneapolis

"Lester Zick" wrote in message
...
On 29 Dec 2006 03:54:29 -0800, "George Dishman"
wrote:

Repeating my previous reply of the 24th in reply to your
copy in the original thread:

George, since your post is a reply to your original reply to me I may
miss certain of your comments which appear as previously posted
material. If I overlook something of importance please let me know.
But I think this post-reply sequence has gotten long enough and I
would like to trim it down to some kind of basics if you don't mind.

OK, I've tried to trim as much as I could but some
of the sections really need the quoted text as there
is quite a bit of drift.

"George Dishman" wrote in message
...
"Lester Zick" wrote in message
...
On Fri, 22 Dec 2006 10:23:17 -0000, "George Dishman"
wrote:
"Lester Zick" wrote in message
om...
On Thu, 21 Dec 2006 10:02:52 -0000, "George Dishman"
wrote:
"Lester Zick" wrote in message
news:crfjo25d95k8gm2ie0cfitg51mtebvn0c6@4ax .com...
On Mon, 18 Dec 2006 23:38:36 -0000, "George Dishman"
wrote:

....

Explanations are transfers of understanding and the
method by which that is communicated makes no
difference. Whether I explain in maths or words or
as a diagram or even if I present it as a Broadway
musical, as long as you grasp my meaning the medium
is irrelevant.

Well the problem is whether I grasp your meaning in the same way you
do.

That's always a difficulty and it means that it has to
be a collaborative effort, you need to make as much
effort to see what I am saying as I did to present it
(and vice versa of course).

It's the same problem I've always had with analogical and exemplary
arguments. It's the socratic dialectical method cast in the form of
pictures or anything else such as a stage play or whatever. Socrates
used to reason expositionally by dialectical example and analogy
instead of analytically. The problem is that there is no guarantee
what his examples may actually have meant in universal terms. All we
have is his word or claim that this or that analogy or example really
conveyed this or that meaning and not some other meaning entirely.

Yes, there is an onus on him to look at his words and
anticipate how they might be misread and add qualifiers
to eliminate those ambiguitities.

This is exactly where modern mathematikers go wrong with their models.
By and large they're just not exhaustive. It isn't that their models
aren't accurate models; it's what exactly their accurate models are
models of.

That's where physics goes beyond maths. It isn't just the
equations but also the definitions of what measureable
parameter the symbols represent that creates the full
definition.

And until we understand that in exact mechanical and
universal terms there is no point to asserting that this or that model
is a correct model for the point we're trying to establish.

Correctness is a different matter. Given clear definitions
of the symbols, an equation gives an unambiguous prediction
so is by far the best way of conveying an understanding.
Whether that is correct or not means going back to actual
experiments for comparison.

If you reflect on the rather disputatious discussions we had regarding
globular clusters I seem to recollect that you or Jeff or perhaps both
of you thought some pictures were worth a thousand words whereas I was
of the opinion that conservation of angular momentum is dependent on
and a product of radius and kinetic energy is not. So a depiction of
any pictorial or other model which does not model that fundamental
circumstance cannot be an accurate depiction.

Yes, that was a good example. We both know Newtonian
momentum is p = m*v for a single body and that KE is
m/2 * v^2, and the symbols are easily defined but the
statistics of a large ensemble of chaotically moving
objects are less familiar, and that's where the
problem lay.

A number of people tried different methods to show how
Newtonian mechanics explains in words, I chipped in
with some maths, the Virial teorem, and finally there
was the simulation which implemented the Newtonian
definitions exactly but none of them managed to convey
the understanding. Admittedly we didn't try the Broadway
musical but I doubt that would have helped. In the end
we failed to communicate but what other method do you
think we could have tried? If you were in my position,
how would you go about the problem?

My concern is that unless we can find some way to share
views at least to the point where we can make reasonable
criticisms of each others reasoning, then all the
discussions will end in the same way.

There are two problems here, showing how changes in the coordinate
geometry of space can vary with respect to velocity through space ..

Not "with respect to velocity through space", it varies with
the velocity of the frame with respect to the other frame.

And that relative velocity is through space.

You cannot measure or define speed relative to the
vacuum, what I said is correct, the velocity used in
the Lorentz transforms and derived length contraction
formula relate to frames and objects, not space itself.

Yes but what we're, or at least I, am trying to establish is whether
space is a void or vacuum and whether light travels through space at
some constant velocity independent of objects in space and whether
that velocity through space can be measured by means of MM or kindred
experiments. That's the whole point to SR and my analysis of it and
interstitial bodies and frames of reference. So there's no point to
simply saying it ain't so since that's what we're trying to determine.

My point here is that you are trying to force your own
view into the conversation as a given, SR does not say
that "light travels through space at some constant
velocity independent of objects in space" or as you
said to start "vary with respect to velocity through
space" so before we start any discussion, we need to
agree what SR really says. I am sure we can agree SR
treats space as a vacuum (though that might be harder if
we move on to GR where the nature of the metric is always
contentious) but that precludes any notion of a speed
relative to space.

Well sure except that's the same as saying there is contraction of
some kind whether material or geometric and that that's the
explanation for the null results of MM.

Yes, there is a contraction but the key is what you
are ignoring, the difference between the geometric
and a 'material' or 'physical' contracton.

Only because I don't understand what you mean by a difference between
the two.

I can see that so I have to find a better way to
communicate what I mean. Once you grasp that, then
you can argue about it if you want to. I'll try to
do something after Christmas.

Okay. I don't see that there can be a geometric contraction which
doesn't affect objects measured according to the geometric metric but
I'm certainly willing to listen.

I not saying it doesn't affect objects, but then I've
said that before so maybe you didn't listen, or maybe
I didn't say it clearly enough. Anyway, how about you
take it on board this time and from now on don't
suggest I am saying there is no effect.

combining your second response

"Lester Zick" wrote in message
...
On 29 Dec 2006 03:54:29 -0800, "George Dishman"
....
SR explains that change of length not as a physical contraction
(like thermal changes) but as a rotation in the x-t plane due
to the relative motion.

I don't know what the latter means ..

That is the one area that is at the root of all our
disagreements.

Okay but it's your claim not mine. If you want to use it to justfiy
the conversion of Lorentzian anisotropy in the context of MM to
Einstein's isotropy it's your responsibility to explain how the
transformation occurs and not mine.

It's not my responsibility to teach anything, if you
want to learn SR it is your responsibility to study
it. Taylor and Wheeler would probably be the best
book to use. However, I will try to explain sometime
in the holidays. Words don't work for you so I'll have
to try something else.

Okay. But I'm not interested in SR.

Well there are only two explanations that I know of,
that of Lorentz where objects interact with the aether
and that of SR which relies on 4D geometry. I can't
tell you about anything other than those two so pick
your poison or this has to be the limit of the
conversation. Be aware though that having made your
choice, there is no point in my writing anything
unless you make an equal effort to absorb it. You have
to approach reading my responses with the attitude of
wanting to understand what I am saying at least to the
level of being able to say why it is wrong rather than
closing your ears to what you don't like as some people
do.

I'll c&p a bit from the bottom to illustrate this:

Put two stakes in the ground a metre apart. Stand
10m from the midpoint where your line of sight to
the midpoint makes an angle of 30 degrees to the
line between the stakes. Have a friend stand 10m
from the midpoint but at 45 degrees. The angle
subtended for each of you is 'contracted' compared
to what you would see if your line of sight was
perpendicular to the line between the stakes. You
see different 'contraction factors' because you
are standing in different places. Now add two more
stakes but set the line between them at 10 degrees
to that between the original pair. To ensure they
"overlap in space", make sure the midpoints coincide.
Again you and your friend see different factors but
they are not the same as the first pair. For the
Lorentz Transforms, the values depend on speed
instead of location but other than that there is no
difference in the _logic_. Your argument doesn't
show any contradiction.

I don't see different contraction factors.

Don't you? If that is true, this is a case where you need
to read the paragraph again and try to see where those
factors are. The angle subtended as seen by the observer
at 30 degrees is 2.87 degrees while for the observer at
45 degrees it becomes 4.06 degrees. In this analogy it isn't
lengths but subtended angles that are contracted.

The key to communication is that you need to put some
effort into understanding my words as I do to following
yours so don't just say "I don't see ..", ask specific
questions about it. I'll do that next.

The math of SR and Lorentz
transforms show different contraction factors. And when different
contraction factors overlap there is a contradiction between speed of
light transiting one frame of reference and the other through common
regions of space.

You should be able to see there is no contradiction for
two observers seeing different subtended angles between
the stakes even though they are physically the same
distance apart - they are in fact the same stakes. Can
you explain to me why you think a contradiction appears
when this same rezoning is applied to lengths instead of
angles?

I'm interested in geometric
contraction as an explanation for the transition between Lorentz
anisotropic transforms and Einsteins's isotropic results. If you
maintain SR explains the transition in the context of interstitial
bodies it is certainly your responsibility to explain how that is
possible.

No it isn't. Education isn't free, you normally pay for
courses and you are still expected to do your homework.
If you want me to provide you with an explanation of
something that you currently don't understand, I am
willing to lay out the explanation for free but the cost
is that you have to put in as much effort understanding
it as I will in laying it out.

At another level, SR was published by Einstein over a
century ago and has been studied by thousands of people
over Avery conceivable situation. It has been proven
mathematically that it cannot contain contradictions so
the onus is on you to back what is an "extraordinary
claim" with at least a clear statement of what you think
the problem actually is.

The Lorentz transformations are only concerned with the
relative longitudinal and transverse speed of light with respect to
an
experimental platform and not with any rotations in space.

Not rotation in space, rotation in spacetime.

Then I still don't have any idea what that means. The Lorentz
transformations are what they are in space ...

No, remember the transforms work on all four coordinates.

Which means what exactly with respect to interstitial bodies and
coincident frames of reference?

"interstitial bodies" are bodies that lie between other
things. In this diagram m1 and m2 are MMX experiments
carried out within labs in two different star systems.

( n1 ) m1 ( n2 ) m2 ( n3 )

The regions n1, n2 and n3 bounded by the brackets are
nebulae. m1 and m2 are moving towards n2 but at different
speeds. m1 and m2 are "interstitial bodies" between the
nebulae. Please explain why you think the existence of
the nebulae has any significance for SR's explanation of
length contraction of m1 and m2 as seen by some third
party observer, for example one at rest relative to n2.

I was talking of a single arm. A single arm can have
as many lengths as there as frames in which it is
measured.

And a single experimental arm can have as many interstitial arms
within it ..

"between it", interstitial means between.

So what? "Interstitial" meaning "between" can have as many frame of
reference definitions as there are particles within arms moving at
different velocities.

As I said above:

... A single arm can have
as many lengths as there as frames in which it is
measured.

Measurement is a frame-dependent process. What is your
point.

Each speed gives uniform contraction to object moving
with uniform (meaning the same) speed. All the parts
of any one MMX are moving with uniform speed so it
works. Any other MMX moving at a different speed still
has all its parts moving that the same "uniform" speed
so you get "uniform contraction". Still no problem

Uniform contraction is a speed dependent variable. The problem is that
you can have different speeds within any MM experiment and different
uniform contraction factors.

Yes, so? Different observers get different measured lengths
because the measurement process gives frame dependent results.
Lester, I think this is an example where we are failing to
communicate and I don't think we will improve following this
line.

There is a problem if two different arms are supposed to have two
different lengths in two different frames of reference together.

Two arms, A and B measured in two frames K0 and K1 can
give four different lengths: A in K0, A in K1, B in K0
and B in K1. I don't see any contradiction in that.

If arms overlap one another it doesn't matter how they're measured.
They can't uniformly contract in such a way as to produce the null
results of MM conducted along both arms in different reference frames
together.

Since each is moving at uniform speed, there isn't a
problem. If they aren't separated in the direction
perpendicular to the motion of course the bodies will
impact, but that's hardly a concern for the Lorentz
Transforms, only those standing nearby :-)

I don't understand what this means.

It's a joke. If you have one MMX on a slab of marble moving
from left to right at 0.6c parallel to the x axis and another
moving from right to left at 0.8c, there will be a heck of
a bang when they overlap unless there is some separation
between them in the y or z axes. The serious point is a
request for you to clarify what you mean by "overlap". It
can't mean two solid objects occupying the same space at the
same time while in relative motion.

Alternatively you might try going back to the start of the
quoted text and see if you can explain why you said "There
is a problem ...". What problem do you envisage?

However when the same bodies are interstitial and
overlap one another in different frames of reference different
contraction factors apply to each and that's where the contradiction
occurs.

Why, they have different values because they are measured
in different frames so there is no contradiction. If they
were supposed to have different values _without_ some other
change then I could see your point but not when there is an
obvious cause for the difference.

It really doesn't matter how they're measured. It can't happen. Let's
supposed for the sake of argument there is some other operative factor
we'll call X whether it's your rotation in spacetime or anything else.
The problem is that X has to transform Lorentz's transformations which
are anisotropic into Einstein's or anyone elses isotropic results.

Try working the example I suggested above and you
will see that works OK.

I don't see anything of the kind. You've got at least two different
contraction factors supposedly applicable to the same interstitial
bodies and regions of space.

Did you work the problem?

Each factor only applies to one observer so neither sees
a contradiction (two values for the same observer would
be contradictory of course) and they have different speeds
relative to the body being measured so the fact that the
observers get different factors isn't a contradiction
either (different factors for the same speed would be
contradictory of course).

I am still looking for you to tell me where this supposed
contradiction appears.

You
have at least two different contraction factors M and N which are
applicable to a common overlapping area of space occupied by the
overlapping interstitial experimental arms.

No, M is uniformly applicable to all of one MMX while
N is uniformly applicable to all of the other. Each
applies to bodies moving at a one particular speed.

The problem is that M and N overlap one another and light for each
experiment has to pass through both.

What do you mean by "M and N overlap one another"?
These are different mathematical factors. For
example, a 4m long MMX moving at 0.6c from left to
right is measured as being 3.2m long (contraction
ratio M=0.8) while a 3m MMX moving at 0.8c from right
to left is measured being 1.8m long (contraction
ratio N=0.6).

So application of any one
contraction factor to that common space either averages out with the
other contraction factor or can't apply uniformly.

That makes no sense at all. One and only one factor
applies to each observer since the factor is dependent
on the speed of the observer relative to the body.

I'm not talking about observers.

Yes you are, you are talking of the "contraction factor"
which is how one observer's measurement differs from
that of another.

I'm talking about the relative speed
of light. That's what has to transit space to produce Einstein's
isotropic effects. Lorentz transforms show the relative speed of light
to be anisotropic.

The speed of light is c for all inertial observers.

George

George Dishman replied to Lester Zick:

measureable parameter

I don't grok the use of the term "parameter". I use the
term "quantity". Length, area, volume, time, speed, mass,
momentum, electric charge, electric current, thermodynamic
temperature, and light intensity are examples of measurable
quantities. On the other hand, "quantity" is also a
synonym for "amount", as in "the quantity of sand", "the
quantity of light", and so forth, which is a different
meaning, and likely to cause confusion.

To me, the term "parameter" indicates an engineering
specification rather than a measureable quantity-- even
though it *IS* a measureable quantity. Hmph!

What do you think?

My point here is that you are trying to force your own
view into the conversation as a given

That is exactly what I wanted to say in my last post, but
couldn't articulate, so I gave up and deleted my attempts.
You said more than I was attempting to say, with 1/3 the
number of words.

Can you explain to me why you think a contradiction
appears when this same rezoning is applied to lengths
instead of angles?

At another level, SR was published by Einstein over a
century ago and has been studied by thousands of people
over Avery conceivable situation.

Using a spelling checker, I see.

The serious point is a request for you to clarify what you
mean by "overlap". It can't mean two solid objects occupying
the same space at the same time while in relative motion.

I think that one use Lester makes of his term "interstitial
bodies" is the atoms and molecules within a body. Each
particle has its own instantaneous velocity, different from
the velocities of the other particles within the body, and
Lester cannot see how each one of those particles can have
a "contraction factor" different from the body as a whole.

I am still looking for you to tell me where this supposed
contradiction appears.

The apparent contradiction is obvious, even if Lester
prefers to describe it in somewhat convoluted terms.
I think that instead of your current line of attack, you
should acknowledge that the apparent contradiction is
obvious, and then ask Lester to show that it is real and
not merely apparent.

I'm somewhat curious why he thinks his statement of the
apparent contradiction is more clear-cut than mine.

His version is that SR says multiple bodies in the same
place, moving relative to one another, simultaneously
have different "contraction factors".

My version is that SR says a body simultaneously has
different "contraction factors" for different observers
in different states of motion relative to the body.

The two statements are equivalent, but I think mine is
more shockingly obvious in its apparent contradiction.

The apparent contradiction that Lester is complaining
about is probably the single most common hangup when
just starting to learn about relativity. I would not
be surprised to learn that the majority of people are
confounded by it for at least a short time.

-- Jeff, in Minneapolis

"Jeff Root" wrote in message
oups.com...

George Dishman replied to Lester Zick:

measureable parameter

I don't grok the use of the term "parameter". I use the
term "quantity". Length, area, volume, time, speed, mass,
momentum, electric charge, electric current, thermodynamic
temperature, and light intensity are examples of measurable
quantities. On the other hand, "quantity" is also a
synonym for "amount", as in "the quantity of sand", "the
quantity of light", and so forth, which is a different
meaning, and likely to cause confusion.

To me, the term "parameter" indicates an engineering
specification rather than a measureable quantity-- even
though it *IS* a measureable quantity. Hmph!

What do you think?

The term to means has connotations of being an independent
variable, or an argument to a routine in software, but it
was what sprang to mind. "Quantity" to me is more to do with
a measure representing an assay, length of string, area,
volume and mass are good examples but the others I would
generally term just as "measurables" but really quantity
is just as good.

Can you explain to me why you think a contradiction
appears when this same rezoning is applied to lengths
instead of angles?

At another level, SR was published by Einstein over a
century ago and has been studied by thousands of people
over Avery conceivable situation.

Using a spelling checker, I see.

:-(

The serious point is a request for you to clarify what you
mean by "overlap". It can't mean two solid objects occupying
the same space at the same time while in relative motion.

I think that one use Lester makes of his term "interstitial
bodies" is the atoms and molecules within a body. Each
particle has its own instantaneous velocity, different from
the velocities of the other particles within the body, and
Lester cannot see how each one of those particles can have
a "contraction factor" different from the body as a whole.

I won't speculate here on what he means. Instead, look
at the various definitions thrown up by a Google search:

http://www.google.co.uk/search?q=define%3A+interstitial

Interstitial means lying in the interstices such as
carbon grains in the interstices between the steel
grains in cast iron, or fluid in the gaps between
cells in muscle. The particles comprising a body are
not interstitial but what I want is for Lester to
actually explain what he means rather than us guessing.

I am still looking for you to tell me where this supposed
contradiction appears.

The apparent contradiction is obvious, even if Lester
prefers to describe it in somewhat convoluted terms.

So you say but I don't think so. It is obvious that,
for a single body, you get different factors for
different observers moving at different speeds because,
as Lester said himself, the effects are velocity
dependent. He seems to have some reasoning that says
this explanation doesn't work when more than one body
is involved _and_ we talk about spaces inside bodies
_and_ the bodies are overlapping. Why those extra
conditions are necessary is a mystery to me.

I think that instead of your current line of attack, you
should acknowledge that the apparent contradiction is
obvious, and then ask Lester to show that it is real and
not merely apparent.

No, I just want him to state why he thinks there is
a contradiction in such a way that it makes clear
why all these extra provisos are necessary. I'm not
going to make his case for him, there is no
contradiction in anything he has presented so far
so it is his task to try to justify his claim. I
don't think he can and he uses rhetorical questions
to cover it up in the hope that is readers will fill
it in for him.

I'm somewhat curious why he thinks his statement of the
apparent contradiction is more clear-cut than mine.

I am sure he is saying that your version doesn't
show the contradiction but his does.

His version is that SR says multiple bodies in the same
place, moving relative to one another, simultaneously
have different "contraction factors".

No, his version has the space between bodies being
contracted and remember he first said each observer
only observed his _own_ MMX.

My version is that SR says a body simultaneously has
different "contraction factors" for different observers
in different states of motion relative to the body.

The two statements are equivalent, but I think mine is
more shockingly obvious in its apparent contradiction.

Yours is the classic statement but Lester seems to
think he has a new problem that goes beyond the
standard resolution of your statement.

The apparent contradiction that Lester is complaining
about is probably the single most common hangup when
just starting to learn about relativity. I would not
be surprised to learn that the majority of people are
confounded by it for at least a short time.

Perhaps, but let's not invent our own problems, Lester
needs to make a clear statement of the problem. Maybe
it is just what you have said but maybe he has some
other problem in mind.

Happy New Year
George

On 31 Dec 2006 07:00:42 -0800, "Jeff Root" wrote:


George Dishman replied to Lester Zick:

measureable parameter

I don't grok the use of the term "parameter". I use the
term "quantity". Length, area, volume, time, speed, mass,
momentum, electric charge, electric current, thermodynamic
temperature, and light intensity are examples of measurable
quantities. On the other hand, "quantity" is also a
synonym for "amount", as in "the quantity of sand", "the
quantity of light", and so forth, which is a different
meaning, and likely to cause confusion.

To me, the term "parameter" indicates an engineering
specification rather than a measureable quantity-- even
though it *IS* a measureable quantity. Hmph!

What do you think?

My point here is that you are trying to force your own
view into the conversation as a given

That is exactly what I wanted to say in my last post, but
couldn't articulate, so I gave up and deleted my attempts.
You said more than I was attempting to say, with 1/3 the
number of words.

But the problem is who is trying to force what view on whom. I haven't
gotten to George's reply as yet but I'm simply posing a problem as far
as contraction is concerned. I don't see anyone imposing anything on
anyone. If SR answers the objection I'd simply like to know how.

Can you explain to me why you think a contradiction
appears when this same rezoning is applied to lengths
instead of angles?

At another level, SR was published by Einstein over a
century ago and has been studied by thousands of people
over Avery conceivable situation.

Using a spelling checker, I see.

The serious point is a request for you to clarify what you
mean by "overlap". It can't mean two solid objects occupying
the same space at the same time while in relative motion.

I think that one use Lester makes of his term "interstitial
bodies" is the atoms and molecules within a body. Each
particle has its own instantaneous velocity, different from
the velocities of the other particles within the body, and
Lester cannot see how each one of those particles can have
a "contraction factor" different from the body as a whole.

I agree. However exactly the same objection applies even if
macroscopic interstitial bodies are considered. Previously I've
mentioned MM conducted between the earth and moon and
some other body at right angles. Same principle applies if we consider
another MM conducted on a satellite between the earth
and moon. Uniform contraction can't apply to both because the frames
of reference overlap whether microscopic or macroscopic bodies are
considered.

I am still looking for you to tell me where this supposed
contradiction appears.

The apparent contradiction is obvious,

Well thank goodness someone besides Gurcharn gets it.

even if Lester
prefers to describe it in somewhat convoluted terms.

I think the more accurate description would be "general" than
"convoluted". I'm trying to point out certain implications of velocity
dependent frames of reference when it comes to contraction hypotheses.
I think that instead of your current line of attack, you
should acknowledge that the apparent contradiction is
obvious, and then ask Lester to show that it is real and
not merely apparent.

Well, Jeff, the definition of bodies and frames of reference in
corporeal and geometric terms is purely velocity dependent.
Appearances have nothing to do with how they're defined or
whether or how they can contract if they do.

I'm somewhat curious why he thinks his statement of the
apparent contradiction is more clear-cut than mine.

His version is that SR says multiple bodies in the same
place, moving relative to one another, simultaneously
have different "contraction factors".

My version is that SR says a body simultaneously has
different "contraction factors" for different observers
in different states of motion relative to the body.

Why bring "observers" into the problem at all? Either frames of
reference are defined according to a common velocity or they aren't.
If they are either different contraction factors apply to each or they
don't. And if different contraction factors apply to overlapping
bodies either they contradict one another or they don't. I don't see
there is any "appearance" or apparent contraction involved. The
contradiction doesn't apply to any hypothetical observers but to a
body in relative motion. Whether observers observe anything is
irrelevant to whether there is a contradiction between contractions.

The two statements are equivalent, but I think mine is
more shockingly obvious in its apparent contradiction.

Actually the two statements are not quite equivalent, Jeff. If you
insist on observation consider the identical case where only one
observer is involved for MM in both interstitial bodies.

The apparent contradiction that Lester is complaining
about is probably the single most common hangup when
just starting to learn about relativity. I would not
be surprised to learn that the majority of people are
confounded by it for at least a short time.

But the real problem here is that they can't put the problem into
words. A lot of people recognize the problem but can't quite put their
fingers on the contradiction involved. As far as I know I'm the first
to put the issue in definitive terms: that both coporeal and geometric
contraction operates across spatial definitions which are velocity
dependent. At least despite considerable research I've never read of
anyone else who managed to describe the problem in definitive terms.

Everyone talks about observers and measurements but the really curious
thing is that despite all the talk no one observes or measures
anything. They all talk about this and that resolution of the paradox
but no one actually shows how contradictory contractions are supposed
to occur.

You have to remember that these contradictory contraction factors are
not just nominal. They're supposed to reflect the speed of light as it
transits the space contracted this way or that. The Lorentz transforms
which describe the speed of light in various directions relative to an
underlying platform at constant velocity are anisotropic and apply
across space independent of the platform. Einstein's speed of light
results across space are isotropic. And what we're looking for in that
context is some explanation as to how that is possible. It isn't that
observers can measure this or that according to these or those rods or
cones.It's that light has to transit space independent of any platform
and do so at different velocity to make Lorentz transforms isotropic.

Having said which however I have to mention you at least seem to get
it. I think Gurcharn also gets it. However I'm not sure George does.
In any event I appreciate the contribution and look forward to further
discussion.

~v~~

On 31 Dec 2006 03:47:48 -0800, "George Dishman"
wrote:


"Lester Zick" wrote in message
.. .
On 29 Dec 2006 03:54:29 -0800, "George Dishman"
wrote:

Repeating my previous reply of the 24th in reply to your
copy in the original thread:

George, since your post is a reply to your original reply to me I may
miss certain of your comments which appear as previously posted
material. If I overlook something of importance please let me know.
But I think this post-reply sequence has gotten long enough and I
would like to trim it down to some kind of basics if you don't mind.

OK, I've tried to trim as much as I could but some
of the sections really need the quoted text as there
is quite a bit of drift.

I'm pretty concerned with accessablity and turnaround here, George. A
lot of people who might otherwise be interested would be turned off by
the length. What I'd like to suggest is instead of trying to reply to
a whole message all at once just replying to isolated topics instead
but covering all the issues raised in sequence. At least that's the
only way I can think of to do justice to all the issues raised. If
you're agreeable I'd like to try that on the next go round.

"George Dishman" wrote in message
...
"Lester Zick" wrote in message
...
On Fri, 22 Dec 2006 10:23:17 -0000, "George Dishman"
wrote:
"Lester Zick" wrote in message
news:atllo212aoksu2u76kd4o1lg1bi8798ceg@4ax. com...
On Thu, 21 Dec 2006 10:02:52 -0000, "George Dishman"
wrote:
"Lester Zick" wrote in message
news:crfjo25d95k8gm2ie0cfitg51mtebvn0c6@4a x.com...
On Mon, 18 Dec 2006 23:38:36 -0000, "George Dishman"
wrote:

...

Explanations are transfers of understanding and the
method by which that is communicated makes no
difference. Whether I explain in maths or words or
as a diagram or even if I present it as a Broadway
musical, as long as you grasp my meaning the medium
is irrelevant.

Well the problem is whether I grasp your meaning in the same way you
do.

That's always a difficulty and it means that it has to
be a collaborative effort, you need to make as much
effort to see what I am saying as I did to present it
(and vice versa of course).

Sure.

It's the same problem I've always had with analogical and exemplary
arguments. It's the socratic dialectical method cast in the form of
pictures or anything else such as a stage play or whatever. Socrates
used to reason expositionally by dialectical example and analogy
instead of analytically. The problem is that there is no guarantee
what his examples may actually have meant in universal terms. All we
have is his word or claim that this or that analogy or example really
conveyed this or that meaning and not some other meaning entirely.

Yes, there is an onus on him to look at his words and
anticipate how they might be misread and add qualifiers
to eliminate those ambiguitities.

Well it's more than that. All the qualifiers in the world can't tell
you what someone actually meant to convey. That's why we have all the
common middle terms of Aristotelian syllogistic inference in science
instead of Socratic dialectical analogies and story telling.

This is exactly where modern mathematikers go wrong with their models.
By and large they're just not exhaustive. It isn't that their models
aren't accurate models; it's what exactly their accurate models are
models of.

That's where physics goes beyond maths. It isn't just the
equations but also the definitions of what measureable
parameter the symbols represent that creates the full
definition.

Okay. But we still need to know the mechanics underlying measurable
parameters to understand why, if, and how measurable parameters apply.

And until we understand that in exact mechanical and
universal terms there is no point to asserting that this or that model
is a correct model for the point we're trying to establish.

Correctness is a different matter. Given clear definitions
of the symbols, an equation gives an unambiguous prediction
so is by far the best way of conveying an understanding.
Whether that is correct or not means going back to actual
experiments for comparison.

But we still wouldn't know whether particular equations do describe a
situation accurately. It's not enough just to extrapolate equations in
descriptive or illustrative terms unless we know definitely if, how,
and why they apply as they're supposed to.

If you reflect on the rather disputatious discussions we had regarding
globular clusters I seem to recollect that you or Jeff or perhaps both
of you thought some pictures were worth a thousand words whereas I was
of the opinion that conservation of angular momentum is dependent on
and a product of radius and kinetic energy is not. So a depiction of
any pictorial or other model which does not model that fundamental
circumstance cannot be an accurate depiction.

Yes, that was a good example. We both know Newtonian
momentum is p = m*v for a single body and that KE is
m/2 * v^2, and the symbols are easily defined but the
statistics of a large ensemble of chaotically moving
objects are less familiar, and that's where the
problem lay.

A number of people tried different methods to show how
Newtonian mechanics explains in words, I chipped in
with some maths, the Virial teorem, and finally there
was the simulation which implemented the Newtonian
definitions exactly but none of them managed to convey
the understanding. Admittedly we didn't try the Broadway
musical but I doubt that would have helped. In the end
we failed to communicate but what other method do you
think we could have tried? If you were in my position,
how would you go about the problem?

Well without trying to revisit the earlier problem in detail I would
simply note that the absence of angular momentum in a particular
direction implies gravitational contraction in that direction despite
the presence of kinetic energy. That's the way I approached the
problem and it's all I really did. Both aggregate kinetic energy and
zero net angular momentum can be conserved despite centripetal
collapse because kinetic energy is not directional.

My concern is that unless we can find some way to share
views at least to the point where we can make reasonable
criticisms of each others reasoning, then all the
discussions will end in the same way.

Yeah, that's a real problem when radical issues are analyzed in
fundamentally different terms. I've bitten my tongue more than once
just as I'm sure you and others have. I think it helps to understand
that the issues raised are not merely raised in captious terms.

There are two problems here, showing how changes in the coordinate
geometry of space can vary with respect to velocity through space ..

Not "with respect to velocity through space", it varies with
the velocity of the frame with respect to the other frame.

And that relative velocity is through space.

You cannot measure or define speed relative to the
vacuum, what I said is correct, the velocity used in
the Lorentz transforms and derived length contraction
formula relate to frames and objects, not space itself.

Yes but what we're, or at least I, am trying to establish is whether
space is a void or vacuum and whether light travels through space at
some constant velocity independent of objects in space and whether
that velocity through space can be measured by means of MM or kindred
experiments. That's the whole point to SR and my analysis of it and
interstitial bodies and frames of reference. So there's no point to
simply saying it ain't so since that's what we're trying to determine.

My point here is that you are trying to force your own
view into the conversation as a given, SR does not say
that "light travels through space at some constant
velocity independent of objects in space" or as you
said to start "vary with respect to velocity through
space" so before we start any discussion, we need to
agree what SR really says. I am sure we can agree SR
treats space as a vacuum (though that might be harder if
we move on to GR where the nature of the metric is always
contentious) but that precludes any notion of a speed
relative to space.

Except I'm trying to confine my remarks to what SR or Lorentz for that
matter says with respect to contraction whether corporeal or
geometric. I'm specifically trying to avoid any involved discussion
with regard to what SR says in other respects because based on
everything else I've seen people discuss the potential seems endless.

I've considered the problem of Lorentz speed of light anisotropy in
relation to Einstein's speed of light isotropy in detail and I can see
no alternative to uniform contraction for conversion of one to the
other. I'm not trying to impose my view on anyone but I am trying to
emphasize what I consider the critical analytical path given these
physical parameters. That's why my original schematic was drawn
without reference to observers, measurement, and so on. I wanted to
avoid the impression that what I'm talking about is only an apparent
problem as Jeff seems to think. The contraction has to be real if it's
to explain the transition between Lorentz's transforms and Einstein's.

Well sure except that's the same as saying there is contraction of
some kind whether material or geometric and that that's the
explanation for the null results of MM.

Yes, there is a contraction but the key is what you
are ignoring, the difference between the geometric
and a 'material' or 'physical' contracton.

Only because I don't understand what you mean by a difference between
the two.

I can see that so I have to find a better way to
communicate what I mean. Once you grasp that, then
you can argue about it if you want to. I'll try to
do something after Christmas.

Okay. I don't see that there can be a geometric contraction which
doesn't affect objects measured according to the geometric metric but
I'm certainly willing to listen.

I not saying it doesn't affect objects, but then I've
said that before so maybe you didn't listen, or maybe
I didn't say it clearly enough. Anyway, how about you
take it on board this time and from now on don't
suggest I am saying there is no effect.

I don't or at least wasn't aware that I was implying it. The real
problem I'm having at present is deciding who thinks what the
contraction effect amounts to. Jeff seems to think it's only apparent
or nominal and is to be explained by observers and measurement.
Previously you've mentioned a rotation in space-time which I don't
really understand. As far as I'm concerned contraction has to be a
real physical-spatial effect to explain the transition between Lorentz
anisotropic transforms and Einstein isotropic effects at least to the
extent light transits space independent of matter at constant speed.

combining your second response

George, I appreciate that you've gone to the trouble of combining my
preceeding replies but I really would like to keep them separate to
shorten individual posts and increase turnaround significantly. At
least it seems to me like the material thus far is more philosophical
than technical. During the holidays there is so much football etc.
going on that I feel the need to reduce the hours longer replies take.

~v~~

On 31 Dec 2006 03:47:48 -0800, "George Dishman"
wrote:


"Lester Zick" wrote in message
.. .

[. . .] reply to second part of message.

"Lester Zick" wrote in message
.. .
On 29 Dec 2006 03:54:29 -0800, "George Dishman"
...
SR explains that change of length not as a physical contraction
(like thermal changes) but as a rotation in the x-t plane due
to the relative motion.

I don't know what the latter means ..

That is the one area that is at the root of all our
disagreements.

Okay but it's your claim not mine. If you want to use it to justfiy
the conversion of Lorentzian anisotropy in the context of MM to
Einstein's isotropy it's your responsibility to explain how the
transformation occurs and not mine.

It's not my responsibility to teach anything, if you
want to learn SR it is your responsibility to study
it. Taylor and Wheeler would probably be the best
book to use. However, I will try to explain sometime
in the holidays. Words don't work for you so I'll have
to try something else.

Okay. But I'm not interested in SR.

Well there are only two explanations that I know of,
that of Lorentz where objects interact with the aether
and that of SR which relies on 4D geometry. I can't
tell you about anything other than those two so pick
your poison or this has to be the limit of the
conversation. Be aware though that having made your
choice, there is no point in my writing anything
unless you make an equal effort to absorb it. You have
to approach reading my responses with the attitude of
wanting to understand what I am saying at least to the
level of being able to say why it is wrong rather than
closing your ears to what you don't like as some people
do.

Well, George, I don't know how much point there can be to continued
conversation where SR is the topic instead of contraction. The problem
I see is that most people only see two alternatives: Lorentz and SR.
Contraction is a real, physical, and geometric effect needed to bridge
the gap between Lorentzian anisotropy in the speed of light and
Einstein's isotropy. So either we're stuck there or we need to see the
difficulty presented by coincident reference frames and interstitial
bodies and resolve that difficulty in mechanical terms.

I'll c&p a bit from the bottom to illustrate this:

Put two stakes in the ground a metre apart. Stand
10m from the midpoint where your line of sight to
the midpoint makes an angle of 30 degrees to the
line between the stakes. Have a friend stand 10m
from the midpoint but at 45 degrees. The angle
subtended for each of you is 'contracted' compared
to what you would see if your line of sight was
perpendicular to the line between the stakes. You
see different 'contraction factors' because you
are standing in different places. Now add two more
stakes but set the line between them at 10 degrees
to that between the original pair. To ensure they
"overlap in space", make sure the midpoints coincide.
Again you and your friend see different factors but
they are not the same as the first pair. For the
Lorentz Transforms, the values depend on speed
instead of location but other than that there is no
difference in the _logic_. Your argument doesn't
show any contradiction.

I don't see different contraction factors.

Don't you? If that is true, this is a case where you need
to read the paragraph again and try to see where those
factors are. The angle subtended as seen by the observer
at 30 degrees is 2.87 degrees while for the observer at
45 degrees it becomes 4.06 degrees. In this analogy it isn't
lengths but subtended angles that are contracted.

I've read the paragraph several times and all I can take away from it
is that you're talking about observers measuring things. So where is
the contraction?

The key to communication is that you need to put some
effort into understanding my words as I do to following
yours so don't just say "I don't see ..", ask specific
questions about it. I'll do that next.

Specific questions about what? I understand measurement relativity.
Where's the contraction?All I see is people talking about measurement.
I don't see anyone actually measuring contraction.

The math of SR and Lorentz
transforms show different contraction factors. And when different
contraction factors overlap there is a contradiction between speed of
light transiting one frame of reference and the other through common
regions of space.

You should be able to see there is no contradiction for
two observers seeing different subtended angles between
the stakes even though they are physically the same
distance apart - they are in fact the same stakes. Can
you explain to me why you think a contradiction appears
when this same rezoning is applied to lengths instead of
angles?

Two observers seeing different subtended angles? So what? Let's get
down to basics. What about one observer seeing two different angles
overlapping each other because different contraction factors apply to
them? That's the contradiction at least insofar as MM is concerned.

I'm interested in geometric
contraction as an explanation for the transition between Lorentz
anisotropic transforms and Einsteins's isotropic results. If you
maintain SR explains the transition in the context of interstitial
bodies it is certainly your responsibility to explain how that is
possible.

No it isn't. Education isn't free, you normally pay for
courses and you are still expected to do your homework.

My homework? And what about the education I'm trying to provide you.
You aren't paying a nickel for that. I've proposed what appears to me
to be a novel problem with different contraction factors applied to
interstitial bodies and coincident frames of reference. Jeff gets it
although he seems to consider it only an apparent problem involving
observers and measurement. Gurcharn gets it. You don't get it.

If you want me to provide you with an explanation of
something that you currently don't understand, I am
willing to lay out the explanation for free but the cost
is that you have to put in as much effort understanding
it as I will in laying it out.

Well I could say that based on prior conversations I already
understand more of SR than yourself. However rather than doing so let
me observe that I've proposed a novel issue in contradictory
contraction factors applied to interstitial bodies and coincident
reference frames which other people grasp. And my impression is that
you either don't understand this problem or maintain SR solves it
according to some kind of rotation in 4D spacetime. And the problem I
have with your explanation is contradictory rotations in 4D spacetime
for interstitial bodies and coincident frames of reference are still
contradictory wherever they're supposed to occur.

At another level, SR was published by Einstein over a
century ago and has been studied by thousands of people
over Avery conceivable situation. It has been proven
mathematically that it cannot contain contradictions so
the onus is on you to back what is an "extraordinary
claim" with at least a clear statement of what you think
the problem actually is.

Well that's what I depicted graphically early on in about as clear a
statement of the problem as I can imagine. SR may not contain
contradictions. It's spatial and geometric contraction which contains
contradictions when different contraction factors are supposed to
apply to interstitial bodies and coincident frames of reference in any
uniform way necessary to vitiate results in MM conducted in each.
Underlying assumptions of what is possible in physical terms is not
included in mathematical demonstrations of consistency.

The Lorentz transformations are only concerned with the
relative longitudinal and transverse speed of light with respect to
an
experimental platform and not with any rotations in space.

Not rotation in space, rotation in spacetime.

Then I still don't have any idea what that means. The Lorentz
transformations are what they are in space ...

No, remember the transforms work on all four coordinates.

Which means what exactly with respect to interstitial bodies and
coincident frames of reference?

"interstitial bodies" are bodies that lie between other
things. In this diagram m1 and m2 are MMX experiments
carried out within labs in two different star systems.

( n1 ) m1 ( n2 ) m2 ( n3 )

The regions n1, n2 and n3 bounded by the brackets are
nebulae. m1 and m2 are moving towards n2 but at different
speeds. m1 and m2 are "interstitial bodies" between the
nebulae. Please explain why you think the existence of
the nebulae has any significance for SR's explanation of
length contraction of m1 and m2 as seen by some third
party observer, for example one at rest relative to n2.

Well you're making the common mistake Einstein and most others made
about the possibility and implications of interstitial bodies. What is
spatially preemptive about m1 and m2? You could just as easily
interstitially define m1 and m2 overlapping one another or m2 wholly
contained within m1. Nothing to do with observation.Either contraction
occurs or it doesn't. Without contraction there is no conventional
explanation for either for MM or Lorentz anisotropic transforms and
Einstein's isotropy.

I was talking of a single arm. A single arm can have
as many lengths as there as frames in which it is
measured.

And a single experimental arm can have as many interstitial arms
within it ..

"between it", interstitial means between.

So what? "Interstitial" meaning "between" can have as many frame of
reference definitions as there are particles within arms moving at
different velocities.

As I said above:

... A single arm can have
as many lengths as there as frames in which it is
measured.

Measurement is a frame-dependent process. What is your
point.

My point is that contraction is also a velocity dependent and frame
dependent process and not a measurement dependent process.

Each speed gives uniform contraction to object moving
with uniform (meaning the same) speed. All the parts
of any one MMX are moving with uniform speed so it
works. Any other MMX moving at a different speed still
has all its parts moving that the same "uniform" speed
so you get "uniform contraction". Still no problem

Uniform contraction is a speed dependent variable. The problem is that
you can have different speeds within any MM experiment and different
uniform contraction factors.

Yes, so? Different observers get different measured lengths
because the measurement process gives frame dependent results.
Lester, I think this is an example where we are failing to
communicate and I don't think we will improve following this
line.

I agree. As long as you consider the problem one of measurement
nothing will improve. That's why I didn't cast the problem in those
terms.

There is a problem if two different arms are supposed to have two
different lengths in two different frames of reference together.

Two arms, A and B measured in two frames K0 and K1 can
give four different lengths: A in K0, A in K1, B in K0
and B in K1. I don't see any contradiction in that.

If arms overlap one another it doesn't matter how they're measured.
They can't uniformly contract in such a way as to produce the null
results of MM conducted along both arms in different reference frames
together.

Since each is moving at uniform speed, there isn't a
problem. If they aren't separated in the direction
perpendicular to the motion of course the bodies will
impact, but that's hardly a concern for the Lorentz
Transforms, only those standing nearby :-)

I don't understand what this means.

It's a joke. If you have one MMX on a slab of marble moving
from left to right at 0.6c parallel to the x axis and another
moving from right to left at 0.8c, there will be a heck of
a bang when they overlap unless there is some separation
between them in the y or z axes. The serious point is a
request for you to clarify what you mean by "overlap". It
can't mean two solid objects occupying the same space at the
same time while in relative motion.

"Solid objects"? What "solid objects"? Since when are objects solid?
Not since Democritus have I heard anyone suggest molecular and atomic
matter as any kind of residual atomic monads. Matter as we conceive
the term is only nominally preemptive in spatial terms. As we define
experimental platforms of the MM type we could use almost any kind of
spatially remote points such as the earth and moon and other bodies to
conduct the experiment and other experimental platforms could be used
within and among them to conduct similar experiments.

Alternatively you might try going back to the start of the
quoted text and see if you can explain why you said "There
is a problem ...". What problem do you envisage?

If I have the correct "problem" mentioned there would be two different
contraction factors applicable to each and the uniformly null results
characteristic of MM experiments in general would not be possible.

However when the same bodies are interstitial and
overlap one another in different frames of reference different
contraction factors apply to each and that's where the contradiction
occurs.

Why, they have different values because they are measured
in different frames so there is no contradiction. If they
were supposed to have different values _without_ some other
change then I could see your point but not when there is an
obvious cause for the difference.

It really doesn't matter how they're measured. It can't happen. Let's
supposed for the sake of argument there is some other operative factor
we'll call X whether it's your rotation in spacetime or anything else.
The problem is that X has to transform Lorentz's transformations which
are anisotropic into Einstein's or anyone elses isotropic results.

Try working the example I suggested above and you
will see that works OK.

I don't see anything of the kind. You've got at least two different
contraction factors supposedly applicable to the same interstitial
bodies and regions of space.

Did you work the problem?

Each factor only applies to one observer so neither sees
a contradiction (two values for the same observer would
be contradictory of course) and they have different speeds
relative to the body being measured so the fact that the
observers get different factors isn't a contradiction
either (different factors for the same speed would be
contradictory of course).

I am still looking for you to tell me where this supposed
contradiction appears.

Well, George, Gurcharn and Jeff get it so maybe you can get a better
explanation from them.

You
have at least two different contraction factors M and N which are
applicable to a common overlapping area of space occupied by the
overlapping interstitial experimental arms.

No, M is uniformly applicable to all of one MMX while
N is uniformly applicable to all of the other. Each
applies to bodies moving at a one particular speed.

The problem is that M and N overlap one another and light for each
experiment has to pass through both.

What do you mean by "M and N overlap one another"?
These are different mathematical factors. For
example, a 4m long MMX moving at 0.6c from left to
right is measured as being 3.2m long (contraction
ratio M=0.8) while a 3m MMX moving at 0.8c from right
to left is measured being 1.8m long (contraction
ratio N=0.6).

And when they overlap there is a contradiction such as would preclude
uniformly null results for different MM experiments conducted in each
frame of reference. You seem to be saying interstitial bodies are not
possible which just isn't true.

So application of any one
contraction factor to that common space either averages out with the
other contraction factor or can't apply uniformly.

That makes no sense at all. One and only one factor
applies to each observer since the factor is dependent
on the speed of the observer relative to the body.

I'm not talking about observers.

Yes you are, you are talking of the "contraction factor"
which is how one observer's measurement differs from
that of another.

That's not a contraction factor, George, that's measurement of a
contraction. Different things entirely. Contraction is required to
explain Einstein's isotropy in the context of Lorentz's anisotropy for
the speed of light. Completely immaterial how you measure it.

I'm talking about the relative speed
of light. That's what has to transit space to produce Einstein's
isotropic effects. Lorentz transforms show the relative speed of light
to be anisotropic.

The speed of light is c for all inertial observers.

Whatever. The speed of light and measurement of the speed of light are
completely different. The Lorentz transforms show an anisotropic speed
of light relative to a platform undergoing translation through space
at constant velocity. Contraction is what is used to explain the null
results of MM in that context.

~v~~