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. 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