Dear Mr. Keynon and sirs!

In order to construct the Special theory of relativity (SR), Einstein
advanced two axiom assumption which be called SR's two postulates in
which the second one is "the speed of light c in vacuum is invariant
in all of the inertial reference frames." This axiom assumption can
also be expressed by a simply function that dx/dt=dx'/dt'=dx"/dt"=…=c
or other form x=ct, x'=ct' which we often see in the Lorentz
transformation. If only use this postulate, SRians still can not give
any reasonable explanation for the above questions. However, from the
second axiom assumption SR inherit Lorentz transformation in order to
infer the velocity addition which be in form
v'=(v+vo)/(1+v*vo/c^2) . Getting v=c, yield v'=(c+vo)/(1+vo/c)=c. It
is here! SRians used this equation to interpret on for Einstein that:
the c+v or c-v additions are meaningless, then they understood and
interpreted the idea of the SR's second postulate that "the speed of
light in vacuum is invariant wrt its sources and observers". Thus,
SRians will answer Mr. Keynon's above questions only by SR's velocity
addition equation.
As for me, I can claim that: since accepted the SR's second
postulate, there is still another transformation called the
non-Lorentz transformation in which SR's v'=(v+vo)/(1+v*vo/c^2)
velocity addition equation must be collapsed!
More detail that: if the co-ordinate relationship between two K, K'
inertial frame which travelling at velocity vo wrt each other is
expressed in form
t' = A*t + B*x
x' = D*t + E*x
where A,B,D,E are the functions of vo, the Einstein-Lorentz
transformation yielded the velocity addition equation in form
v'=(v+vo)/(1+v*vo/c^2); but if it is expressed in form
t' = A*t
x' = D*t + E*x
i.e getting B = 0 and where A,D,E are the function of vo, the
Einstein-Lorentz transformation will yield the velocity addition
equation in form v' = v*sqrt(1-vo^2/c^2) + vo, i.e c+uc and c-uc.
This will disclaim the "invariant of c wrt its observers" idea in the
SR's second postulate! In this case, SRians will only able to keep an
unique idea for SR's second postulate that the speed of light is
invariant wrt its sources but not be its observers.
As above, I proved that the velocity addition equation in form
v'=(v+vo)/(1+v*vo/c^2) is only consequence inferring from the form of
function having factor B different with zero. Thus, SRians can not say
that "the invariant of the light speed c wrt its observers is one
foundation idea in SR's second postulate", because of it only is a
consequence inferring from the velocity addition equation being in
form v'=(v+vo)/(1+v*vo/c^2) while still exist another form that
disclaim it!
Otherwise, we knew that the velocity addition equation in form
v'=(v+vo)/(1+v*vo/c^2) is very important in SR&GR. It permit SRians
state that nothing can travel at speed exceed c. It can also defend
the infinity situation in all of SR's equations. And it also is one of
derivations for presenting GR.
The factor B different with zero in above function is the third axiom
assumption which not be mentioned in SR, isn't it? And .. Can SRians
prove that factor B equal zero be wrong and different zero be unique
right?
I am a non-SRian, and this is my challenge to SRians!

Please you, SRians!
Sincerely,
ThanhMinh.

"greywolf42" wrote in message . ..
"Martin Hogbin" wrote in message

Better to say that it has never been measured to have
any value other than c (in a vacuum and an inertial frame
of course).

LOL! If one measures the speed of light, then one is (by definition)
measuring 'c'. But the values are never measured to be 'constant.' What
explicit value are you using?

The value of c is well known. Can you name any experiment in
which light is measured to travel at any speed other than c _in a
vacuum and an inertial frame_.



Light speed varies when moving from one medium to another. (Huygens,
Fresnell)

This is not in a vacuum.


Light speed varies when the media its in is accelerated (Fizeau)


This is not in a vacuum.

Light speed varies in vacuum when moving around a rotating table (Sagnac.)

Not when measured in an inertial frame.


Light speed varies in vacuum on Earth when moving around a *stationary*
table (Michelson-Gale.)


The measurement does not take place in an inertial frame because
the Earth is rotating.



Light speed varies when moving around the Earth (Allan, Weiss, and Ashby).

The measurement does not take place in an inertial frame.


Light is actually faster west than east (Sagnac) and faster down than up
(Einstein.)

This is not an inertial frame.


Light speed varies in vacuum when it passes by anything gravitational
(Shapiro time delay).

The measurement does not take place in an inertial frame.


Martin Hogbin

"Craig Markwardt" wrote in message
news

"greywolf42" writes:
...

The only problem is that the speed of light is never measured to be
constant. It is simply assumed to be so -- by theoretical fiat.

... a statement which is of course unsubstantiated.

Although my statement was not substantiated in the specific post, it has
been substantiated many times on this newsgroup. See my reply to
Martin, (yesterday) for example.

http://www.google.com/groups?selm=gp...lashnews grou
ps.com

http://www.google.com/groups?selm=20...79%40mb-cg.aol.
com
http://www.google.com/groups?selm=20...17%40mb-fj.aol.
com
http://www.google.com/groups?selm=10....supernews.com

Anyone who is aware of the fairly recent redefinition of the meter to be the
'speed of light' multiplied by a certain number of seconds is aware of the
disingeneousness of your statement.

There are many
experiments to measure the constancy of the speed of light. Examples:

Schaefer, B. 1999, PRL, 82, 4964 (constancy of c with frequency)

But this does not show constancy of the speed of light. It says that the
frequency of the light does not change it's speed. Which is trivial for any
non-shock wave in most media.

Will, C. 2001, Living Rev. Rel. 4, 4 (LLI tests in sec 2.1)
http://www.livingreviews.org/lrr-2001-4

This does not address the constancy of the speed of light at all. It is a
paen to GR.

Wolf, P. & Gerrard, P. 1997, PRA, 56, 4405 (isotropicity of c)

Nor does this paper address the issue of constancy of c. In addition, it
uses the GPS system ... which is actively steered. Which makes the entire
paper worthless. It is also worthless because the paper uses Einstein
synchrony. Which artificially puts in a 'constant c' to any measurement by
prerun corrections.

All three simply assume that 'c' is constant. Do you have any experimental
support for your claim?

--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}

"Martin Hogbin" wrote in message
...

"greywolf42" wrote in message
. ..
"Martin Hogbin" wrote in message

Better to say that it has never been measured to have
any value other than c (in a vacuum and an inertial frame
of course).

LOL! If one measures the speed of light, then one is (by definition)
measuring 'c'. But the values are never measured to be 'constant.'
What explicit value are you using?

The value of c is well known.

Excellent! Then you should have no trouble identifying it! What value are
you using?

Can you name any experiment in
which light is measured to travel at any speed other than c _in a
vacuum and an inertial frame_.

As soon as you find me a specific value that you claim is the 'correct'
answer, I will point out at least one experiment that contradicts that
value.

Light speed varies when moving from one medium to another. (Huygens,
Fresnell)

This is not in a vacuum.

Light speed varies when the media its in is accelerated (Fizeau)

This is not in a vacuum.

Light speed varies in vacuum when moving around a rotating table
(Sagnac.)

Not when measured in an inertial frame.

Light speed varies in vacuum on Earth when moving around a *stationary*
table (Michelson-Gale.)

The measurement does not take place in an inertial frame because
the Earth is rotating.

Light speed varies when moving around the Earth (Allan, Weiss, and
Ashby).

The measurement does not take place in an inertial frame.

Light is actually faster west than east (Sagnac) and faster down than up
(Einstein.)

This is not an inertial frame.

Light speed varies in vacuum when it passes by anything gravitational
(Shapiro time delay).

The measurement does not take place in an inertial frame.

OK, I accept all your notes. However, there aren't any measurements that
have been made in pure vacuum or in inertial frames. So where is your
evidence?

Quite simply, you have made a bald statement-by-assertion: "Light speed is
constant for all observers in an inertial frame in a pure vacuum." Hence, it
is up to you to support this claim. As far as I know, all you have going
for you is Einstein's postulate.

--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}

greywolf42 wrote:

"Martin Hogbin" wrote in message
...

"greywolf42" wrote in message

. ..

"Martin Hogbin" wrote in message

Better to say that it has never been measured to have
any value other than c (in a vacuum and an inertial frame
of course).

LOL! If one measures the speed of light, then one is (by definition)
measuring 'c'. But the values are never measured to be 'constant.'
What explicit value are you using?

The value of c is well known.


Excellent! Then you should have no trouble identifying it! What value are
you using?


Can you name any experiment in
which light is measured to travel at any speed other than c _in a
vacuum and an inertial frame_.


As soon as you find me a specific value that you claim is the 'correct'
answer, I will point out at least one experiment that contradicts that
value.


Light speed varies when moving from one medium to another. (Huygens,
Fresnell)

This is not in a vacuum.


Light speed varies when the media its in is accelerated (Fizeau)

This is not in a vacuum.


Light speed varies in vacuum when moving around a rotating table
(Sagnac.)

Not when measured in an inertial frame.


Light speed varies in vacuum on Earth when moving around a *stationary*
table (Michelson-Gale.)

The measurement does not take place in an inertial frame because
the Earth is rotating.


Light speed varies when moving around the Earth (Allan, Weiss, and
Ashby).

The measurement does not take place in an inertial frame.


Light is actually faster west than east (Sagnac) and faster down than up
(Einstein.)

This is not an inertial frame.


Light speed varies in vacuum when it passes by anything gravitational
(Shapiro time delay).

The measurement does not take place in an inertial frame.


OK, I accept all your notes. However, there aren't any measurements that
have been made in pure vacuum or in inertial frames. So where is your
evidence?

Quite simply, you have made a bald statement-by-assertion: "Light speed is
constant for all observers in an inertial frame in a pure vacuum." Hence, it
is up to you to support this claim. As far as I know, all you have going
for you is Einstein's postulate.

Perhaps many models describe an idealized and abstract set of
circumstances to one degree or another. I'm somewhat astounded how
idealized (non-extistent vaccuum) and how abstract (inertial frames)
this one happens to be.

This makes assumptions required for relativity very powerful (indeed,
non-falsifiable by empirical/experimental evidence), since conditions
sufficient to disprove this assumption are either non-existent or arbitrary.



--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}

wrote in message
om...
(Bilge) wrote in message
...
:
Dear Mr. Keynon and sirs!

In order to construct the Special theory of relativity (SR), Einstein
advanced two axiom assumption which be called SR's two postulates in
which the second one is "the speed of light c in vacuum is invariant
in all of the inertial reference frames."

The second postulate is unnecessary. It's sufficient to assume the
first and determine `c' from experiment.

No, actually no!

Please see the following ancient post by Tom Roberts:

http://groups.google.com/groups?q=ph...ent.com&rnum=4

And note from the introduction:

'Many criticisms of Special Relativity center on the "assumption" that
the speed of light is constant in all reference frames. The derivation
given here does not make that assumption; the existence of a universal
speed (c) is a natural consequence of the Postulates forming the basis
of the derivation. General symmetry properties of space-time are
sufficient to determine the equations of the Lorentz Transformation
[to within a topological choice - see below]. The bottom line is that
it is IMPOSSIBLE to formulate an alternative to Special Relativity,
while obeying the observed symmetries of space-time and agreeing with
the experimental evidence [see below about the limitations of the
symmetry postulates used in this derivation].'

Thanks
Bill

The SR's second axiom assumption can be simply
expressed in the math form that x=ct, x'=ct'. It's this permitting
Einstein inherit the Lorentz transformation to infer the
dtau=dt*sqrt(1-v^2/c^2) function representing the "time dilation"
concept in SR. Next, to base on the first axiom assumption that the
functions describing the natural laws have the same form in all of the
inertial frames, SR continue to inherit Newton's motion functions in
which substitute dt by dtau in order to defined all of the foundation
concepts in SR as follow: the relativistic momentum, the relativistic
motion energy, the relativistic mass ... So, to confirm my above
arguments you can reconsider in the text-books.
Thank,
ThanhMinh.

"Robert B. Winn" wrote in message
om...
wrote in message
. com...
(Bilge) wrote in message
...
:
Dear Mr. Keynon and sirs!

In order to construct the Special theory of relativity (SR),
Einstein
advanced two axiom assumption which be called SR's two postulates in
which the second one is "the speed of light c in vacuum is invariant
in all of the inertial reference frames."

The second postulate is unnecessary. It's sufficient to assume the
first and determine `c' from experiment.

No, actually no! The SR's second axiom assumption can be simply
expressed in the math form that x=ct, x'=ct'. It's this permitting
Einstein inherit the Lorentz transformation to infer the
dtau=dt*sqrt(1-v^2/c^2) function representing the "time dilation"
concept in SR. Next, to base on the first axiom assumption that the
functions describing the natural laws have the same form in all of the
inertial frames, SR continue to inherit Newton's motion functions in
which substitute dt by dtau in order to defined all of the foundation
concepts in SR as follow: the relativistic momentum, the relativistic
motion energy, the relativistic mass ... So, to confirm my above
arguments you can reconsider in the text-books.
Thank,
ThanhMinh.

Can you tell me what they are talking about with this?

x'=Ax-Bvt
t'=Dt-Evx

How do they come up with A, B, D, and E?

Homogeneity implies the trandofrmations must be linear - simple argument
from the calculus will show this - a correct but more complex derivation can
be found here http://arxiv.org/abs/physics/0110076.

Bill

Robert B. winn

"Bill Hobba" wrote in message
...

wrote in message
om...
(Bilge) wrote in message
...
:
Dear Mr. Keynon and sirs!

In order to construct the Special theory of relativity (SR),
Einstein
advanced two axiom assumption which be called SR's two postulates in
which the second one is "the speed of light c in vacuum is invariant
in all of the inertial reference frames."

The second postulate is unnecessary. It's sufficient to assume the
first and determine `c' from experiment.

No, actually no!

Please see the following ancient post by Tom Roberts:

http://groups.google.com/groups?q=ph...ty&hl=en&lr =
&group=sci.physics.relativity&selm=54jfst%24glp%40 ssbunews.ih.lucent.com&rnu
m=4

And note from the introduction:

'Many criticisms of Special Relativity center on the "assumption" that
the speed of light is constant in all reference frames. The derivation
given here does not make that assumption; the existence of a universal
speed (c) is a natural consequence of the Postulates forming the basis
of the derivation. General symmetry properties of space-time are
sufficient to determine the equations of the Lorentz Transformation
[to within a topological choice - see below]. The bottom line is that
it is IMPOSSIBLE to formulate an alternative to Special Relativity,
while obeying the observed symmetries of space-time and agreeing with
the experimental evidence [see below about the limitations of the
symmetry postulates used in this derivation].'

Unfortunately, that ancient post has been shown to be defective in several
respects. In this old derivation, Tom refers to 'coordinate systems.'
However, since that time, Tom has had to modify his viewpoint to require
'inertial frames.' Once Tom requires the Lorentz Transform (which is the
historical basis for the 'general symmetry properties of space-time'),
there's nothing left to do. Tom simply reversed the historical basis of
spacetime. Which is trivial, and meaningless.


--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}

"Paul Bramscher" wrote in message
...
greywolf42 wrote:

"Martin Hogbin" wrote in message
...

{snip higher and uncommented levels}

OK, I accept all your notes. However, there aren't any measurements
that have been made in pure vacuum or in inertial frames. So where is
your evidence?

Quite simply, you have made a bald statement-by-assertion: "Light speed
is constant for all observers in an inertial frame in a pure vacuum."
Hence, it is up to you to support this claim. As far as I know, all you
have going for you is Einstein's postulate.

Perhaps many models describe an idealized and abstract set of
circumstances to one degree or another. I'm somewhat astounded how
idealized (non-extistent vaccuum) and how abstract (inertial frames)
this one happens to be.

This makes assumptions required for relativity very powerful (indeed,
non-falsifiable by empirical/experimental evidence), since conditions
sufficient to disprove this assumption are either non-existent or
arbitrary.

I wouldn't consider that 'powerful'. Tautologies may be fun philosophy, but
they have no place in the scientific method.

--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}

"greywolf42" wrote in message ...
"Martin Hogbin" wrote in message
...


OK, I accept all your notes. However, there aren't any measurements that
have been made in pure vacuum or in inertial frames.


Of course not, because there is no such think as a perfect
vacuum or inertial frame just like there is no such thing as
a point mass, a frictionless surface or a massless inextensible
string. This is how physics works; we start with
idealisations and then add in the complications one by one.

So where is your evidence?

I am sure you must be familiar with the evidence that supports
Einstein's postulate by now. Your complaint seems to be that
none of the tests were performed in a perfect vacuum or an
inertial frame. This is true but, of course, the experimenters
(and later physicists) were aware of this. In some cases this
throws doubt on the validity of the results but it is possible to
calculate (independently of relativity) the effects for example
of a medium on the speed of an electromagnetic wave and
in some cases this can be shown to be negligible.

This is no different to the evidence that supports Newtonian
physics. It is never possible to do a perfect experiment;
we do the best we can and then try to estimate the causes of
error.


Quite simply, you have made a bald statement-by-assertion: "Light speed is
constant for all observers in an inertial frame in a pure vacuum." Hence, it
is up to you to support this claim.


You have, no doubt, seen the FAQ on this.

Martin Hogbin