Androcles wrote:

"Jesse Mazer" wrote in message
...


Androcles wrote:



"Jesse Mazer" wrote in message
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Androcles wrote:




"Jesse Mazer" wrote in message
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Androcles wrote:





"Jesse Mazer" wrote in message
...






Of course, before Einstein physicists didn't think Maxwell's laws
would be correct in every observer's reference frame--they
thought they would only hold exactly in the rest frame of the
aether. They would have believed that to state the laws of
electromagnetism in a way that would hold in all frames, you'd
have to replace every x in Maxwell's laws with (x - v*t), where v
represents the observer's velocity relative to the rest frame of
the aether...any derivatives of x would have to be replaced in
the same way, like replacing dx/dt with (dx/dt - v). This would
give a new set of electromagnetic laws which would be
Galilei-invariant, and which would reduce to Maxwell's laws in
the case where v=0.

But a prediction of this Galilei-invariant analogue of Maxwell's
laws would be that for an observer in motion relative to the
aether, light will be observed to move at different speeds in
different directions, relative to himself. Unfortunately this was
not supported by the Michelson-Morley experiment.





The speed of light in diamond, water, air, any transparent medium
is
constant with respect to the medium. MMX fails to support aether.
In MMX, the medium is air. It is as simple as that.





What do you mean "the medium is air"?




I mean that air was used as a medium for light,
by Michelson, in his interferometer, of course.
He did not perform the experiment in an evacuated chamber, on the
surface
of the moon, or aboard the ISS.







My point was that when waves are considered as a vibration in a
medium, like sound waves, the speed of any wave will be constant
with respect to the rest frame of the medium.




Your points are invariance, x-vt, Maxwell's laws, derivatives,
aether and
anything else you can mention hoping to cover the issue, but you
omitted
to say anything about the physical medium used and asked me what I
meant by it, so clearly it was NOT your point, it is MY point.

Recall that Einstein's second postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body".




Maxwell's laws also say that light's velocity is independent of the
state of motion of the emitting body,



For light in a medium. Maxwell believed in aether.



Who cares what Maxwell believed? Maxwell's laws are just a set of
equations telling you how charged objects interact with the
electromagnetic field, and how the electromagnetic field in turn
affects the movements of charged objects. You don't have to believe in
aether



I do not, but Maxwell did. OK? So whatever Maxwell's "laws" may be,
they are premised on aether. There is no aether, so Maxwell has no law.
If you wish to discuss Maxwell's equations, we can do that. I refuse
to discuss Maxwell's "laws".
[snip]


No, you're wrong. Maxwell's equations are premised on empirical
observations. Physicists don't believe in aether anymore, but they still
use Maxwell's equations to make predictions about electromagnetic
fields, because the predictions of these equations STILL AGREE WITH
EXPERIMENTS. Are you disagreeing with this?






This is a pure mathematical consequence of the equations of Maxwell's
laws.


[snip]



For reference, Maxwell's equations themselves can be found he

http://hyperphysics.phy-astr.gsu.edu...ric/maxeq.html



I see Gauss, Faraday and Ampere.


Yes, many of the set of equations known as "Maxwell's laws" had already
been discovered before Maxwell. But Maxwell was the first to write down
the complete set of equations for the electromagnetic field, hence this
collection of equations is known as "Maxwell's laws". If you don't like
this terminology, feel free to come up with some other name for this set
of six equations, and we can use that name for the rest of our
discussion; the equations will be the same either way.

Here's another site which also refers to these equations as "Maxwell's
equations", so you can verify that I'm using the standard terminology:

http://en.wikipedia.org/wiki/Maxwell's_equations





You can see that "the speed of light is c" is not a
tacked-on-assumption,



Ampere uses it. It IS a tacked on assumption.


Ampere's law does not say anything about the speed of light. The fact
that "the speed of electromagnetic waves = c" was something *derived*
from Maxwell's laws, not something assumed, is verified by the wikipedia
page I just posted:

Furthermore, Maxwell showed that the four equations, with his
correction, predict waves of oscillating electric

of oscillating electric and magnetic fields that travel through empty
space at a speed that could be predicted from simple electrical
experimentsusing the data available at the time, Maxwell obtained a
velocity of 310,740,000 m/s. Maxwell (1865) wrote:

This velocity is so nearly that of light, that it seems we have
strong reason to conclude that light itself (including radiant
heat, and other radiations if any) is an electromagnetic
disturbance in the form of waves propagated through the
electromagnetic field according to electromagnetic laws.

Maxwell was correct in this conjecture, though he did not live to see
its vindication by Heinrich Hertz in 1888. Maxwell's quantitative
explanation of light as an electromagnetic wave is considered one of
the great triumphs of 19th-century physics.


What's interesting here is that Maxwell seems to not have even realized
that light might be just a form of electromagnetic wave until *after* he
calculated the velocity of waves in the electromagnetic field, based on
the values of the permittivity and permeability of free space, factors
which are determined by experiments that on the surface have nothing to
do with light. Only when he saw that the calculated value for the speed
of electromagnetic waves was very close to the empirically-observed
velocity of light did he conjecture that they were one and the same.

If you don't believe that light is an electromagnetic wave, then you are
going to have to explain this apparent "coincidence" that experiments to
determine the factors mu0 and epsilon0 also happen to tell you the
velocity of light when you calculate 1/squareroot(mu0*epsilon0).


I also see mu0 and epsilon0, properties of aether.
That is the tacked on assumption.


Again, modern physicists still use Maxwell's equations, but they don't
assume these are properties of aether, they are just arbitrary constants
needed to translate between the D and H fields and the E and B fields.
Their value is determined by experiment, not by any theory of aether.

Again, the reason Maxwell's equations are still around is just that they
are very successful at making predictions. If you don't agree with this,
then you need to do more reading about electromagnetism, because it's an
unarguable fact.






regardless of whether you have the relativistic understanding of
these laws (that they hold in all reference frames)



Michelson was intending to use doppler shift to measure the
the speed of light in the aether as the Earth flew through it. He was
certainly NOT claiming the speed of light was invariant. Neither was
Maxwell. Both believed time and distance are invariant, as indeed
they are.



Yes, they believed that Maxwell's laws only worked in a single
preferred reference frame. But in relativity, which neither Michelson
nor Maxwell believed in (because it hadn't been invented yet), if
Maxwell's laws are true in one reference frame they must be true in
all of them (because they have the mathematical property of
Lorentz-invariance).



Mathematical properties of aether. There is no aether. yawn


Physicists don't believe in aether today, but they still use Maxwell's
equations to calculate the behavior of the electromagnetic field. Why?
BECAUSE THEY GIVE CORRECT PREDICTIONS. This is the only reason
physicists use *any* set of equations. The equations are just
mathematical relationships between different variables, just because
Maxwell believed in aether doesn't mean the equations themselves have
anything to do with aether.

The equations were mostly *not* derived from any assumptions about
aether, even though physicists happened to believe in aether. Maxwell's
addition to the laws was the prediction of the "displacement current",
and according to the page at
http://maxwell.byu.edu/~spencerr/websumm122/node72.html he did make use
of the concept of aether in making this prediction, but the prediction
has been *verified by experiment* and thus must be accepted regardless
of whether you believe in aether or not (and again, none of the
physicists who use Maxwell's equations today believe in aether).






But this does not fit with the predictions of classical
electromagnetism,



Of course it doesn't! Classical electrodynamics uses aether. THERE
IS NO AETHER.


When I use the term "classical electromagnetism" I am just referring to
the EQUATIONS of Maxwell's laws. You can use these equations without
believing in aether--THE EQUATIONS THEMSELVES SAY NOTHING ABOUT AETHER.




and you don't have an alternate theory that can replicate all of the
successful predictions of classical electromagnetism.



I've told you. I do not have a theory at all. All theories are the work
of others. What I have is a discovery. I'm telling you about the
discovery.
The speed of light, in a vacuum, is source dependent, just like a
bullet from a gun. YOU figure out the theory.


You don't have a "discovery" that has been confirmed by experiments
showing that the speed of light is measured to be a different depending
on the velocity of the source. All you have is a belief. So if
physicists have a neat set of equations that make agree with all the
thousands of experiments that have been done in electromagnetism, and
which predict that the velocity of electromagnetic waves is independent
of the velocity of the source, they are not going to give them up unless
there is strong experimental evidence that they give the wrong
predictions, *or* unless someone can come up with another set of
equations that *also* agree with all these thousands of experiments but
which predict the velocity of light is source-dependent.






All speeds are relative to something.
When requesting a drink on a plane, my speed relative to the flight
attendant is also zero, even though travelling at 500 mph ground
speed
and 250 mph by the air speed indicator.
The speed of light inside a plane, as with the speed of sound, is
relative.




That's because the plane carries its own little pocket of air with
it,



So does MMX, so we can put that one to bed. MMX has nothing
whatever to do with Einstein's relativity. Have it struck from the
FAQ's, which are a biased and prejudiced sham, a disgrace to science.



Should the theory of electromagnetism (the non-quantum version, ie
Maxwell's equations) also be struck from the FAQ's? It seems that it
conflicts just as badly with your ideas.



Your problem. I detect bugs other people's work, and Einstein's
paper has a bug in it. His '½' in
½[tau(0,0,0,t)+tau(0,0,0,t+x'/(c-v)+x'/(c+v))] = tau(x',0,0,t+x'/(c-v))
is a wild guess and totally absurd.


I'd have to look up the meaning of that equation, but I can assure you
that the only assumptions Einstein made were that light would be
measured to travel the same speed in all frames, and that the laws of
physics work the same way in all frames. All the equations of special
relativity, presumably including that one, follow directly from these
assumptions. If you like I can show you how.

Jesse

Androcles wrote:

"Jesse Mazer" wrote in message
...


Androcles wrote:



You saying it doesn't make it so, and since I know you of old as
another
big-headed know-it-all, more interested in trolling than recognizing
simple
solutions, I saw fit to simply deny your assertions.

I will now give the proof.
I place two identical evacuated tubes at right angles, with mirrors
and with
sources and detectors of light.
When the light reaches a detector, it turns off the source.
When NO light reaches the detector, it turns the source on.
The path length can be any reasonable one.
I connect the outputs of the detectors to an up/down counter, one for
up
and the other for down. I calibrate the tube lengths until there is no
count.
I now have MMX, electronic version and air free.
I rotate the apparatus 90 degrees and what happens? NO count happens.
Acording to SR, and there being velocity as the Earth moves and
rotates
x' = (x-vt)/ sqrt(1-v^2/c^2)
y' = y.
So, x' does not equal y'.
The speed of flight in both tubes is c (invariant),
and the tubes are of different lengths.
Therefore a count will occur, the x (up) count exceeding the count of
the
(y) down counter.



Are you saying SR predicts the time light takes to travel down each
tube will depend on how the tubes are oriented, or on the velocity of
the tubes in your reference frame?


No.


OK, then I'm having trouble following your description of the
experiment--could you please tell me what the variables x, y, x' and y'
in your equations above represent physically?

Jesse

Androcles wrote:

In a reference frame in which the apparatus is stationary, x and y
don't
change as the apparatus is rotated (assuming x and y are the
arm-lengths).



Exactly. So you prove nothing. However, Einstein's postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body"
Reference :
http://www.fourmilab.ch/etexts/einstein/specrel/www/

The Earth is moving in the empty space, which is the reference frame.
Are you trying to deliberately obfuscate the problem?


Empty space doesn't have a particular reference frame in Einstein's
theory. One observer moving inertially in empty space may see the earth
moving at 0.8c, another may see it moving at 0.1c, another may see it at
rest (at least, for short amounts of time when the earth's path is not
visibly curved). Since there is no "Absolute Space" in relativity,
Einstein's statement would apply to any one of these reference frames.





No frequency shifts, since there is no relative motion, no
wavelengths shifts, so no change after rotation.

Do you dispute this?



Yes. Michelson and Maxwell thought there was aether and that
was indeed the rest frame. It is also Einstein's rest frame, he is
saying so by his second postulate and modifying the PoR so that
c = (c+v)/(1-v/c)

First, you wrote that equation incorrectly, it should be (c + v)/(1 + v/c)

Second, you continue to use that equation as if it was a "theory" of
Einstein's, when in fact it can be proved true by simple algebra:

(1 + v/c) = (1/c)*(c + v), by multiplying out the 1/c

so by substitution, (c + v)/(1 + v/c) = (c + v)/(1/c)*(c+v)

The (c+v) in the numerator and the denominator cancel out, leaving
1/(1/c), which of course is equal to c.

I would guess that the postulate you are thinking of is the formula for
addition of velocities, w = (u + v)/(1 + uv/c^2), explained on
http://math.ucr.edu/home/baez/physic.../velocity.html ...if
you plug in u=c, then this equation becomes (c + v)/(1 + v/c), and since
the algebra above shows that this is equal to c regardless of the value
of v, this shows that anything that's moving at c in one reference frame
will be moving at c in any other reference frame.

You challenged me in previous posts to derive the Lorentz equations from
(c + v)/(1 + v/c), but when I asked for clarification you didn't
respond...were you asking if the Lorentz equations can be derived from
the relativistic velocity addition formula, w = (u + v)/(1 + uv/c^2)?

You want to obfuscate the problem by declaring v = 0, satisfying
c+v = c+0 = c. If you declare that, then the problem is solved and
SR is irrelevant. The speed of Michelson's light is source dependent.
Without a |v| 0, SR vanishes without a trace.


SR will make exactly the same predictions about the result of the
experiment regardless of the value of v.






The speed of flight in both tubes is c (invariant),
and the tubes are of different lengths.
Therefore a count will occur, the x (up) count exceeding the count of
the
(y) down counter.


In a reference frame in which the MMX apparatus is moving, yes,
according
to SR, there is a length contraction. The length contraction applies
equally to the wavelength in the contracted arm, so the length as
measured
in wavelengths along the arm remains exactly the same.



That has nothing to do with the *speed* of light. Speed is defined as
distance/time. The distance along the contracted arm is less that
the distance along the transverse arm. How much you contract the
wavelength of the light to cram in the same count of wavelenghts along
the contracted arm is completely irrelevant. Time is the same in both
arms.


No, if one arm is contracted in my reference frame, then the time will
also be less, so light will travel at the same speed down both arms.



In the moving frame,



MOVING WITH RESPECT TO WHAT?
You can't have a moving frame unless you define what the rest frame is.



Presumably he meant moving with respect to the rest frame of the
interferometer in the MMX.




the arm along the motion is contracted
by 1/gamma, so we have x' = y'/gamma. The mirror moves at v, so the
light,
moving at c in the moving frame, moves at c-v towards the mirror, as
measured in the moving frame, and takes y'/(gamma (c-v)) to get there.
The
return journey is at c+v relative to the detector, as measured in the
moving frame, so the return journey takes y'/(gamma (c+v)). Therefore
the
total time along that arm for the round trip is

y'/gamma * (2c/(c^2 - v^2)).



There ya go.
You've just contradicted the invariance of the speed of light.
I'm done.
Androcles.


His math seems to be incorrect--it's better to analyze this problem
using the full Lorentz transformations. Suppose the two tubes have
length L. In the rest frame of the tubes, let tube A lie along the
x-axis and tube B lie along the y-axis. So if the two tubes intersect at
the origin, the coordinates of the end of tube A are x=L, y=0 and the
coordinates of the end of tube B are x=0, y=L. In the tube's rest frame,
if we send light pulses from the origin along both tubes at time t=0,
then it will hit the end of tube A at coordinates x=L, y=0 and t = L/c;
the other pulse will hit the end of tube B at coordinates x=0, y=L, t=L/c.

Now consider the perspective of an observer who is moving along the
x-axis at velocity v, and who defines his x' and y' axes to be parallel
to the x and y axis of the tube's frame, with the origin of his x'-y'
coordinate system coinciding with the origin of the x-y coordinate
system at time t=0 in the tube's frame and time t'=0 in his frame. We
can use the Lorentz transformations to find the space/time coordinates
of the light pulses hitting the ends of the tubes in his frame. For the
event of the pulse hitting the end of tube B, the Lorentz
transformations tell us:

x' = gamma*(x - vt), so plugging in x=0, t=L/c we get x' = gamma*(-vL/c)
y' = y, so y' = L
t' = gamma*(t - vx/c^2), so t' = gamma*(L/c)

If the pulse moved gamma*(-vL/c) along the x'-axis and L along the
y'-axis, then using the pythagorean theorem, the light travelled a total
distance of squareroot(gamma^2*(-vL/c)^2 + L^2) =
squareroot(v^2*L^2/c^2*(1 - v^2/c^2) + L^2) = squareroot(v^2*L^2/(c^2 -
v^2) + L^2*(c^2 - v^2)/(c^2 - v^2)) = squareroot(c^2*L^2/(c^2 - v^2)) =
squareroot(c^2*L^2/(c^2)*(1 - v^2/c^2)) = squareroot(L^2/(1 - v^2/c^2))
= L/squareroot(1 - v^2/c^2) = gamma*L

So it travelled a distance of gamma*L in a time of gamma*(L/c), meaning
the speed to travel down tube B was c in this frame.

For the event of the pulse hitting the end of tube A, we have:

x' = gamma*(x - vt), so plugging in x=L, t=L/c we get x' = gamma*(L -
vL/c) = gamma*(Lc/c - vL/c) = gamma*(1/c)*(Lc - Lv)
y' = y, so y' = 0
t' = gamma*(t - vx/c^2), so t' = gamma*(L/c - vL/c^2) = gamma*(Lc/c^2 -
vL/c^2) = gamma*(1/c^2)*(Lc - Lv)

So if you take distance/time to find the speed, the factors of gamma and
(Lc - Lv) cancel out, leaving you with (1/c)/(1/c^2), which is equal to
c. So, the speed to travel down tube A was c in this frame.

Jesse

"Jesse Mazer" wrote in message
...


Androcles wrote:

"Jesse Mazer" wrote in message
...

Androcles wrote:


"Jesse Mazer" wrote in message
...


Androcles wrote:



"Jesse Mazer" wrote in message
...



Androcles wrote:




"Jesse Mazer" wrote in message
.. .





Of course, before Einstein physicists didn't think Maxwell's
laws would be correct in every observer's reference frame--they
thought they would only hold exactly in the rest frame of the
aether. They would have believed that to state the laws of
electromagnetism in a way that would hold in all frames, you'd
have to replace every x in Maxwell's laws with (x - v*t), where
v represents the observer's velocity relative to the rest frame
of the aether...any derivatives of x would have to be replaced
in the same way, like replacing dx/dt with (dx/dt - v). This
would give a new set of electromagnetic laws which would be
Galilei-invariant, and which would reduce to Maxwell's laws in
the case where v=0.

But a prediction of this Galilei-invariant analogue of
Maxwell's laws would be that for an observer in motion relative
to the aether, light will be observed to move at different
speeds in different directions, relative to himself.
Unfortunately this was not supported by the Michelson-Morley
experiment.




The speed of light in diamond, water, air, any transparent
medium is
constant with respect to the medium. MMX fails to support
aether.
In MMX, the medium is air. It is as simple as that.




What do you mean "the medium is air"?



I mean that air was used as a medium for light,
by Michelson, in his interferometer, of course.
He did not perform the experiment in an evacuated chamber, on the
surface
of the moon, or aboard the ISS.






My point was that when waves are considered as a vibration in a
medium, like sound waves, the speed of any wave will be constant
with respect to the rest frame of the medium.



Your points are invariance, x-vt, Maxwell's laws, derivatives,
aether and
anything else you can mention hoping to cover the issue, but you
omitted
to say anything about the physical medium used and asked me what I
meant by it, so clearly it was NOT your point, it is MY point.

Recall that Einstein's second postulate is
"light is always propagated in empty space with a definite
velocity c which is independent of the state of motion of the
emitting body".



Maxwell's laws also say that light's velocity is independent of the
state of motion of the emitting body,


For light in a medium. Maxwell believed in aether.


Who cares what Maxwell believed? Maxwell's laws are just a set of
equations telling you how charged objects interact with the
electromagnetic field, and how the electromagnetic field in turn
affects the movements of charged objects. You don't have to believe
in aether


I do not, but Maxwell did. OK? So whatever Maxwell's "laws" may be,
they are premised on aether. There is no aether, so Maxwell has no
law.
If you wish to discuss Maxwell's equations, we can do that. I refuse
to discuss Maxwell's "laws".
[snip]


No, you're wrong. Maxwell's equations are premised on empirical
observations.

(Sigh).
Here's an empirical observation.
http://www.androc1es.pwp.blueyonder....r/00918-ck.gif
Maxwell's "laws" are NOT based on that empirical observation, and
there are many more like it than Maxwell (or YOU) have never looked at.
http://www.britastro.org/vss/gifc/00107-de.gif
http://www.britastro.org/vss/gifc/00135-di.gif
http://www.britastro.org/vss/gifc/00164-dg.gif
http://www.britastro.org/vss/gifc/00470-dg.gif
http://www.britastro.org/vss/gifc/00526-di.gif
http://www.britastro.org/vss/gifc/00359-de.gif
http://www.britastro.org/vss/gifc/00588-db.gif
http://www.britastro.org/vss/gifl/00029.gif
http://www.britastro.org/vss/gifl/00054.gif
http://www.britastro.org/vss/gifl/00054.gif



I really don't care if you use air as a medium for light's speed,
because
I agree that the speed of light is medium dependent. I'm sure of it.
Maxwell can base his "laws" on observations made in a medium
until the cows come home, he will never explain that curve, and neither
will you.
I am NOT wrong. YOU are.


Physicists don't believe in aether anymore, but they still use
Maxwell's equations to make predictions about electromagnetic fields,
because the predictions of these equations STILL AGREE WITH
EXPERIMENTS. Are you disagreeing with this?

I'm predicting V1493 Aql will provide another outburst in about 200
years.
Are you disagreeing with me?
Your "physicists" have made every little progress toward controlled
fusion,
they allow relativity to screw them up.





This is a pure mathematical consequence of the equations of Maxwell's
laws.

[snip]


For reference, Maxwell's equations themselves can be found he

http://hyperphysics.phy-astr.gsu.edu...ric/maxeq.html


I see Gauss, Faraday and Ampere.


Yes, many of the set of equations known as "Maxwell's laws" had
already been discovered before Maxwell. But Maxwell was the first to
write down the complete set of equations for the electromagnetic
field, hence this collection of equations is known as "Maxwell's
laws". If you don't like this terminology, feel free to come up with
some other name for this set of six equations, and we can use that
name for the rest of our discussion; the equations will be the same
either way.

Here's another site which also refers to these equations as "Maxwell's
equations", so you can verify that I'm using the standard terminology:

http://en.wikipedia.org/wiki/Maxwell's_equations

Understand this: Mathematics can only DESCRIBE physics. It cannot
BE physics. If Einstein wants to play games pretending that time is
not invariant by claiming the time for light to get to a distant point
is 1/2 the time it takes to make the round trip, just because he can't
figure it out any other way, he's
1) wrong.
2) dead wrong.
3) an idiot savant.





You can see that "the speed of light is c" is not a
tacked-on-assumption,


Ampere uses it. It IS a tacked on assumption.


Ampere's law does not say anything about the speed of light.

I give up.
There is quite clearly a c^2 in the middle box on the page
you referred to. You are wasting my time. I'll accept Gauss,
I will accept Faraday. Ampere has a speed in it. I dnt care
how many times "physicists" have proven Gauss and Faraday,
I'm not clumping it all together and calling it "Maxwell" proven.

Androcles.

"Jesse Mazer" wrote in message
...


Androcles wrote:

In a reference frame in which the apparatus is stationary, x and y
don't
change as the apparatus is rotated (assuming x and y are the
arm-lengths).


Exactly. So you prove nothing. However, Einstein's postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body"
Reference :
http://www.fourmilab.ch/etexts/einstein/specrel/www/

The Earth is moving in the empty space, which is the reference frame.
Are you trying to deliberately obfuscate the problem?


Empty space doesn't have a particular reference frame in Einstein's
theory.
Then light will be source dependent.
Androcles.

Androcles wrote:


Then light will be source dependent.

There you go again. Adding velocities.

Bob Kolker

Androcles wrote:

"Jesse Mazer" wrote in message
...


Androcles wrote:



In a reference frame in which the apparatus is stationary, x and y
don't
change as the apparatus is rotated (assuming x and y are the
arm-lengths).



Exactly. So you prove nothing. However, Einstein's postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body"
Reference :
http://www.fourmilab.ch/etexts/einstein/specrel/www/

The Earth is moving in the empty space, which is the reference frame.
Are you trying to deliberately obfuscate the problem?



Empty space doesn't have a particular reference frame in Einstein's
theory.


Then light will be source dependent.
Androcles.





Nope, not according to the laws of electromagnetism.

Jesse

"Jesse Mazer" wrote in message
...


Androcles wrote:

"Jesse Mazer" wrote in message
...

Androcles wrote:


In a reference frame in which the apparatus is stationary, x and y
don't
change as the apparatus is rotated (assuming x and y are the
arm-lengths).


Exactly. So you prove nothing. However, Einstein's postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body"
Reference :
http://www.fourmilab.ch/etexts/einstein/specrel/www/

The Earth is moving in the empty space, which is the reference
frame.
Are you trying to deliberately obfuscate the problem?


Empty space doesn't have a particular reference frame in Einstein's
theory.

Then light will be source dependent.
Androcles.




Nope, not according to the laws of electromagnetism.

Which one? Gauss, Faraday or Ampere?
Androcles.




Jesse

Androcles wrote:

"Jesse Mazer" wrote in message
...


Androcles wrote:



"Jesse Mazer" wrote in message
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Androcles wrote:




"Jesse Mazer" wrote in message
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Androcles wrote:





"Jesse Mazer" wrote in message
...





Androcles wrote:






"Jesse Mazer" wrote in message
. ..







Of course, before Einstein physicists didn't think Maxwell's
laws would be correct in every observer's reference frame--they
thought they would only hold exactly in the rest frame of the
aether. They would have believed that to state the laws of
electromagnetism in a way that would hold in all frames, you'd
have to replace every x in Maxwell's laws with (x - v*t), where
v represents the observer's velocity relative to the rest frame
of the aether...any derivatives of x would have to be replaced
in the same way, like replacing dx/dt with (dx/dt - v). This
would give a new set of electromagnetic laws which would be
Galilei-invariant, and which would reduce to Maxwell's laws in
the case where v=0.

But a prediction of this Galilei-invariant analogue of
Maxwell's laws would be that for an observer in motion relative
to the aether, light will be observed to move at different
speeds in different directions, relative to himself.
Unfortunately this was not supported by the Michelson-Morley
experiment.






The speed of light in diamond, water, air, any transparent
medium is
constant with respect to the medium. MMX fails to support
aether.
In MMX, the medium is air. It is as simple as that.






What do you mean "the medium is air"?





I mean that air was used as a medium for light,
by Michelson, in his interferometer, of course.
He did not perform the experiment in an evacuated chamber, on the
surface
of the moon, or aboard the ISS.








My point was that when waves are considered as a vibration in a
medium, like sound waves, the speed of any wave will be constant
with respect to the rest frame of the medium.





Your points are invariance, x-vt, Maxwell's laws, derivatives,
aether and
anything else you can mention hoping to cover the issue, but you
omitted
to say anything about the physical medium used and asked me what I
meant by it, so clearly it was NOT your point, it is MY point.

Recall that Einstein's second postulate is
"light is always propagated in empty space with a definite
velocity c which is independent of the state of motion of the
emitting body".





Maxwell's laws also say that light's velocity is independent of the
state of motion of the emitting body,




For light in a medium. Maxwell believed in aether.




Who cares what Maxwell believed? Maxwell's laws are just a set of
equations telling you how charged objects interact with the
electromagnetic field, and how the electromagnetic field in turn
affects the movements of charged objects. You don't have to believe
in aether



I do not, but Maxwell did. OK? So whatever Maxwell's "laws" may be,
they are premised on aether. There is no aether, so Maxwell has no
law.
If you wish to discuss Maxwell's equations, we can do that. I refuse
to discuss Maxwell's "laws".
[snip]



No, you're wrong. Maxwell's equations are premised on empirical
observations.



(Sigh).
Here's an empirical observation.
http://www.androc1es.pwp.blueyonder....r/00918-ck.gif
Maxwell's "laws" are NOT based on that empirical observation


I don't know what that graph represents. Anyway, no, Maxwell's laws are
not based on *that* empirical observation, they are based on *other*
empirical observations involving electricity and magnets. Unless you
disagree with that, then you must agree that Maxwell's laws are based on
empirical observations, not on theories about "aether".





I really don't care if you use air as a medium for light's speed


I don't, because the idea is meaningless. When we say that air is the
medium for the propogation of soundwaves, we mean that soundwaves are
nothing more than *moving variations in the density of the air*--the
"peaks" of the wave are regions where the air is denser, the "valleys"
are where it's less dense. See the illustration of "Longitudinal waves"
on this page:

http://www.gmi.edu/~drussell/Demos/w...avemotion.html

The fact that soundwaves are variations in the density of the medium is
the basis for the idea that soundwaves travel at a constant speed in the
medium's rest frame. Even when light travels through a medium like air,
the peaks and valleys are still assumed to be variations in the
electromagnetic field, not in the density of the air. So there is no
reason whatsoever that *anyone* would think the rest frame of the air
has anything whatsoever to do with the speed of light--this is based
only on your own misunderstanding of what people mean when they say "X
is the medium for a certain type of wave" (they don't just mean that the
wave is travelling through that medium--even when electromagnetic waves
travel through air, air is not the medium for the propogation of these
electromagnetic waves).

because
I agree that the speed of light is medium dependent. I'm sure of it.
Maxwell can base his "laws" on observations made in a medium
until the cows come home


Nonsense, for a couple of reasons. First of all, Maxwell's laws do *not*
predict that the the speed of light has anything to do with the rest
frame of the air. Second of all, all the experiments that form the basis
for Maxwell's laws can easily be done in a vacuum. For example,
Faraday's law is one of the Maxwell equations, and it concerns the fact
that if a conductor (like a copper wire) is placed in a varying magnetic
field, a current will be induced in the conductor. This law can easily
be tested in a vacuum-sealed chamber, for example. The other experiments
which form the basis for Maxwell's laws are equally easy to perform in a
vacuum.




Physicists don't believe in aether anymore, but they still use
Maxwell's equations to make predictions about electromagnetic fields,
because the predictions of these equations STILL AGREE WITH
EXPERIMENTS. Are you disagreeing with this?



I'm predicting V1493 Aql will provide another outburst in about 200
years.
Are you disagreeing with me?


I have no idea what that claim is based on, or what V1493 Aql even is,
since you haven't explained it. But please answer my question--do you
agree or disagree that Maxwell's equations lead to correct predictions
for the thousands of experiments involving electricity and magnetism and
electromagnetic fields that have been done to date?

Yes, many of the set of equations known as "Maxwell's laws" had
already been discovered before Maxwell. But Maxwell was the first to
write down the complete set of equations for the electromagnetic
field, hence this collection of equations is known as "Maxwell's
laws". If you don't like this terminology, feel free to come up with
some other name for this set of six equations, and we can use that
name for the rest of our discussion; the equations will be the same
either way.

Here's another site which also refers to these equations as "Maxwell's
equations", so you can verify that I'm using the standard terminology:

http://en.wikipedia.org/wiki/Maxwell's_equations



Understand this: Mathematics can only DESCRIBE physics. It cannot
BE physics.


All modern physicists would disagree with you. In any case, if you have
a set of equations that have been extremely successful at making
predictions, then even if you say this is only a "description" of
physics, isn't it reasonable to think that any prediction which is in
contradiction with what the equations predict is more likely than not
incorrect?


If Einstein wants to play games pretending that time is
not invariant by claiming the time for light to get to a distant point
is 1/2 the time it takes to make the round trip, just because he can't
figure it out any other way, he's
1) wrong.
2) dead wrong.
3) an idiot savant.


I thought we were talking about electromagnetism, and the prediction
that the speed of light doesn't depend on the velocity of the source.

Anyway, it's not that Einstein couldn't figure it out any other way,
it's that he realized if different observers choose to synchronize
clocks by *assuming* light travels the same speed in both directions,
and if their rulers shrink and their clocks slow down in the manner
suggested by Lorentz, then if Maxwell's laws hold in one observer's
coordinate system they will hold in all observer's coordinate systems.
This is because Maxwell's laws have that mathematical property of
"Lorentz-invariance" which I mentioned earlier. And if all the
fundamental laws of physics are Lorentz-invariant, you can use this to
prove that rulers *must* shrink and clocks *must* slow down in just this
manner. And all the most fundamental laws that have been discovered so
far are, in fact, Lorentz-invariant; time dilation has also been
observed directly in a large number of experiments.







You can see that "the speed of light is c" is not a
tacked-on-assumption,



Ampere uses it. It IS a tacked on assumption.



Ampere's law does not say anything about the speed of light.



I give up.
There is quite clearly a c^2 in the middle box on the page
you referred to.


That's just the modern form, since now we know that light is an
electromagnetic wave. When the laws were formulated, though, that term
would have been expressed in terms of the permittivity and permeability
of free space, which are experimentally determined in ways that have
nothing to do with the speed of light. Of course, now that we know light
is an electromagnetic wave, we can say c = 1/squareroot(epsilon_0*mu_0).
But this was only discovered *after* Maxwell had discovered the complete
set of equations, as I mentioned in a previous post. What is your
explanation for this amazing "coincidence", if you don't believe that
the derivation of the speed of light from Maxwell's laws is correct?

Also, note that Maxwell's laws are usually written in the "differential
form" given on the bottom of that page, and that in that form c does not
appear in Ampere's law.

I'll accept Gauss,
I will accept Faraday. Ampere has a speed in it. I dnt care
how many times "physicists" have proven Gauss and Faraday,
I'm not clumping it all together and calling it "Maxwell" proven.


Ampere's law says that moving currents produce a magnetic field, are you
disagreeing with this? It can easily be demonstrated by placing two
wires next to each other and seeing that when a current is run through
both, they either attract or repel each other, depending on whether the
current is flowing in the same or the opposite direction. Maxwell made
one addition to Ampere's equation, predicting something called the
"displacement current", but this is also not too hard to verify
experimentally using a capacitor--see this page:

http://www.ee.byu.edu/ee/em/displace.htm

So there is just as much experimental justification for accepting
Ampere's law as there is for the others. And there is no getting around
the fact that when you put the equations together, they imply that
electromagnetic waves travel at velocity 1/squareroot(epsilon_0*mu_0)
regardless of the velocity of the source (Maxwell was the first to
discover this--the fact that he was the first to see the consequences of
putting all the laws together is why they are called "Maxwell's laws"
even though the individual equations were mostly discovered by others).

Jesse

Androcles wrote:

"Jesse Mazer" wrote in message
...


Androcles wrote:



"Jesse Mazer" wrote in message
...



Androcles wrote:




In a reference frame in which the apparatus is stationary, x and y
don't
change as the apparatus is rotated (assuming x and y are the
arm-lengths).




Exactly. So you prove nothing. However, Einstein's postulate is
"light is always propagated in empty space with a definite velocity
c which is independent of the state of motion of the emitting body"
Reference :
http://www.fourmilab.ch/etexts/einstein/specrel/www/

The Earth is moving in the empty space, which is the reference
frame.
Are you trying to deliberately obfuscate the problem?




Empty space doesn't have a particular reference frame in Einstein's
theory.



Then light will be source dependent.
Androcles.





Nope, not according to the laws of electromagnetism.



Which one? Gauss, Faraday or Ampere?
Androcles.


The fact that the speed of light is independent of the source can only
be derived using all of Maxwell's laws. But see my comments about
Ampere's law at the end of my latest post--there, I pointed out that in
Maxwell's time the law would not have had a c in it, only the
permittivity and permeability of free space terms (epsilon_0 and mu_0)
whose values had been found by experiments having nothing to do with
light. Maxwell then showed that taken together, the laws imply that
electromagnetic waves always travel at velocity
1/squareroot(epsilon_0*mu_0), and it was only *after* it was noticed
that this number was very close to the measured speed of light that
physicist realized light was just a form of electromagnetic wave.

Jesse