Understanding Einstein's simple derivation of the LorentzTransformation

On Jul 25, 8:45*pm, Tom Roberts wrote:
Tom Adams wrote:
I was wrong about one thing. *Lorentz got the math right by 1904.

Only partly. He got the coordinate transform correct, but not the transform of
Maxwell's equations, specifically of charge density. Poincaré corrected his
mistake in 1905.

But you have to do some algebra to see that Lamor's 1900 equation is
the same as Einstein's 1905 equation.
So, the math was there in 1900. *Einstein just rejected the theory
that gave rise to this math and substituted another theory.

He did not "reject" it, he probably did not know of it.

He probably did not know it in 1905. But he offered a different
basis. I am sure he rejected it when he learned about it. The search
for evidence of aether continued for 30 years or so.

Also, he gave good reasons for rejecting an absolute reference frame
in the 1905 paper, the coil vs magnet issue. (I assume its a good
reason, I don't fully understand the issue he raised.)

Mainly he took a consistent view of the basis for relativity from
1905. He was the first to take this view. That is one of the reasons
he tends to get (almost) all the credit.

And it was not yet a
full-blown theory, it was just several mathematicians exploring the equations of
electrodynamics.

Poincare anticipated the consequences of a full blown theory. And,
Einstein's "assume the speed of light is c in all reference frames"
was arguably less of a full blown theory. Poincare thought that for
decades, since Lorentz's theory predicted the relativity of c and gave
light waves a medium to boot.

But in any case, Einstein's approach is equivalent, which is a
rather strange relationship for you to apply the term "rejected".

The math is equivalent, not the conceptual basis.

Say, rather,
that Einstein published a better approach to this issue, which displayed certain
symmetries of the world in general, and electrodynamics in particular; the
physics community has agreed with this assessment.

Hardly at first. And they had about 50 years to hand him a Nobel for
either special or E=mc**2, and over 30 years to hand him a Nobel for
GR. The physics community declined. It's kind of amazing that he
lived so long and never got a Nobel for describing the general
architecture of the universe.

I am not attacking the theory itself. But it was not that popular
with the physics establishment.

I think we tend to go back and create a community of only Einstein
believers and call that "the physics community" in retrospect. There
probably were not a lot of understanders, much less believers.


Note: when I say "theory", I mean the usual modern meaning: a set of equations
with a description of the meanings of the symbols therein, plus a description of
how to relate at least some of them to measurements in the real world.

Tom Roberts

On Jul 26, 8:35*am, Tom Adams wrote:
On Jul 25, 8:45*pm, Tom Roberts wrote:

Tom Adams wrote:
I was wrong about one thing. *Lorentz got the math right by 1904.

Only partly. He got the coordinate transform correct, but not the transform of
Maxwell's equations, specifically of charge density. Poincaré corrected his
mistake in 1905.

But you have to do some algebra to see that Lamor's 1900 equation is
the same as Einstein's 1905 equation.
So, the math was there in 1900. *Einstein just rejected the theory
that gave rise to this math and substituted another theory.

He did not "reject" it, he probably did not know of it.

He probably did not know it in 1905. *But he offered a different
basis. *I am sure he rejected it when he learned about it. *The search
for evidence of aether continued for 30 years or so.

Also, he gave good reasons for rejecting an absolute reference frame
in the 1905 paper, the coil vs magnet issue. *(I assume its a good
reason, I don't fully understand the issue he raised.)

Not really, for he discussed "the observable phenomenon". Those
suggest that the PoR should be valid for EM as it is for mechanics,
just as it was in Newton's theory - which happened to be based on the
postulate of an absolute reference frame. It appears that Einstein was
not aware of that fact at that time.

Mainly he took a consistent view of the basis for relativity from
1905. *He was the first to take this view. *That is one of the
reasons he tends to get (almost) all the credit.

And it was not yet a
full-blown theory, it was just several mathematicians exploring
the equations of electrodynamics.

Poincare anticipated the consequences of a full blown theory. *And,
Einstein's "assume the speed of light is c in all reference frames"
was arguably less of a full blown theory.

I'm afraid that you missed my comment on that: Einstein's purpose was
to *simplify* the necessary input elements for finding the correct
transformations as much as possible.

*Poincare thought that for
decades, since Lorentz's theory predicted the relativity of c and gave
light waves a medium to boot.

But in any case, Einstein's approach is equivalent, which is a
rather strange relationship for you to apply the term "rejected".

The math is equivalent, not the conceptual basis.

[..]

His conceptual basis was mathematics based on the phenomena itself. As
his predecessors matched a physical model to those same constraints,
there was little room to disagree about the necessary conclusion. :-)

Harald

Just look at Einstein's own words right off the bat:

"Examples of this sort, together with the unsuccessful attempts to
discover any motion of the earth relatively to the “light medium,”
suggest that the phenomena of electrodynamics as well as of mechanics
possess no properties corresponding to the idea of absolute rest."

By rejecting aether, he rejected all theories that follow from it,
including the one's he does not know about like Lorentz's theory.

He did not find a logical contradiction in the aether hypothesis.
Instead, he gave it the status of the theory that there is a invisible
unicorn in the room. But that is rejection.

On Mon, 25 Jul 2011 14:20:43 -0700, K_h wrote:

"Marvin the Martian" wrote in message
...
On Sun, 24 Jul 2011 23:07:33 -0700, K_h wrote:

"Marvin the Martian" wrote in message
...
On Sun, 24 Jul 2011 20:44:53 -0500, Sam Wormley wrote:

On 7/24/11 4:19 PM, Marvin the Martian wrote:
Damn it!!

Einstein did NOT derive the Lorentz transformation.

Wanna bet, Marvin!

The Lorentz transformation was originally the result of attempts by
Lorentz and others to explain how the speed of light was observed to
be independent of the reference frame, and to understand the
symmetries of the laws of electromagnetism. Albert Einstein later
re-derived the transformation from his postulates of special
relativity. The Lorentz transformation supersedes the Galilean
transformation of Newtonian physics, which assumes an absolute space
and time (see Galilean relativity). See:
http://www.fourmilab.ch/etexts/einstein/specrel/www/

He didn't "re-derive" ****.

Einstein derived the equations (called the Lorentz transformations)
from the two postulates of special relativity. Historically, though,
he was not the first to write down those transformations.


He showed how his "postulates" are consistent with the Lorentz
transformation. The Lorentz transformation predates SR - Einstein's
paper

Einstein showed that the Lorentz transformations are a consequence of
the two postulates. All physical laws are the same in all reference
frames and that includes Maxwell's laws.

No. The two "postulates" are a direct result of Maxwell's equations
(which are NOT laws, btw) and the Lorentz transformation. Einstein was
confused.


Wrong. Einstein was not confused. Einstein realized that physical laws
are the same in all frames of reference.

The idea that physical laws are the same in all frames of reference goes
back to Galileo and Newton. Newton's laws are invariant under a Galilean
transformation.

Einstein didn't invent it. If Einstein had bothered, and he should have
checked to see that the Lorentz transformation is the transform under
which Maxwell's equations are invariant. (it is an exercise in upper
division undergrad E&M).

Since Maxwell's equations are invariant, both of his 'postulates' can be
concluded from the transform and Maxwell's equations and they're not
postulates at all.

Too bad if you can't see that.

snip irrelevant stuff

You're impressed that a transformation that was designed to keep
Maxwell's equations invariant... keeps Maxwell's equations invariant.
That, I find amusing.

It is not just Maxwell's laws but all physical laws. Why do you think
that I am "impressed" by anything? I never posted anything about being
"impressed".

You're impressed by it because you keep making the same reference to the
greatness of Einstein's postulates even though both postulates are a
direct result of Maxwell's equations and the Lorentz transform. Someone
who argues against reason is "impressed".


snip irrelevancies

THAT come from? Einstein didn't even believe or understand QM, he had
an irrational belief and a stupid preconceived bias AGAINST Quantum
mechanics (and a few other things, like Lemaitre's Big Bang Theory).


Einstein did understand quantum theory but his only objection was
philosophical. He felt that nature should be deterministic at its core
and it was that part of quantum theory that he did not like.

Besides having a bias against Quantum mechanics and his preconceived
notion of a deterministic universe - which IS a preconceived bias and not
'philosophical', that's just a silly excuse for having a bias -
creationist can claim a 'philosphical' objection to evolution and be just
as (in)valid and just as justified as Einstein's objections to QM.

Einstein also irrationally believed that QM was an 'incomplete theory'
and tried to form a complete theory using "hidden variable'. The attempt
was an exercise in non-science. He clearly didn't have a very good grasp
of the what was scientific and what wasn't when he went down the path of
Voo-Doo-fizicks.

transform has been verified by experiment and thus isn't a postulate
at all, it is a theory.

Correct, the theory of relativity has been experimentally proven
beyond a reasonable doubt. The term "postulate" is just a linguistic
remnant; a way of speaking now and no longer a reference to a
speculative idea.

Actually, length contraction has never been shown experimentally. Don't
overstate the case. The consistency of the speed of light and time
dilation has been shown experimentally.

http://en.wikipedia.org/wiki/
Length_contraction#Experimental_verifications

Your wikipedia article supports my statement that length contraction has
never been demonstrated experimentally.

They reference the Trouton-Rankine experiment, which was an attempt to do
so, but the results were negative.



The second postulate about the speed of light being constant is also
a direct result of Maxwell's equations.

It is a trivial result of relativity but not a direct result of
Maxwell's equations.

The hell it isn't.

It is not a direct result of solving Maxwell's equations. Maxwell's
equations predict speed c for electromagnetic radiation for the frame of
reference in which those equations are valid. It takes the relativity
principle to say that those equations, of Maxwell, are valid in all
frames of reference.

I'm sorry you're ignorant of physics and don't know were velocity appears
in the wave equation. :-D

Once you solve Maxwell's equations for the wave equation, the speed of
the wave, c, falls right out.

Yes, but only in the coordinate system where the equations are solved.

No, under all coordinate systems. Why are you on about transforming a set
of equations with a Galilean transformation when you know damned well
they are not invariant under that transform?! It's the WRONG transform.


snip baseless claims

I'm sorry but I've already made the case, and all you're doing is saying
'not so' and explaining it in still simpler terms for you is boring me.

Try and understand what I said first and then reply something sensible,
please.

On Jul 26, 2:27*pm, Tom Adams wrote:
Just look at Einstein's own words right off the bat:

"Examples of this sort, together with the unsuccessful attempts to
discover any motion of the earth relatively to the “light medium,”
suggest that the phenomena of electrodynamics as well as of mechanics
possess no properties corresponding to the idea of absolute rest."

By rejecting aether, he rejected all theories that follow from it,
including the one's he does not know about like Lorentz's theory.

He did not find a logical contradiction in the aether hypothesis.
Instead, he gave it the status of the theory that there is a
invisible unicorn in the room. *But that is rejection.

It's positivism. And insofar as that suggested a rejection, he
regarded that as a mistake years later. Looking back at the state of
affairs around 1905, he said in 1920 in a discourse* on that topic:

"The next position which it was possible to take up in face of this
state of things appeared to be the following. The ether does not exist
at all. The electromagnetic fields are not states of a medium, and are
not bound down to any bearer, but they are independent realities which
are not reducible to anything else, exactly like the atoms of
ponderable matter. This conception suggests itself the more readily
as, according to Lorentz's theory, electromagnetic radiation, like
ponderable matter, brings impulse and energy with it, and as,
according to the special theory of relativity, both matter and
radiation are but special forms of distributed energy, ponderable mass
losing its isolation and appearing as a special form of energy.

More careful reflection teaches us, however, that the special theory
of relativity does not compel us to deny ether.
[..]
in such space [without an ether] there [..] would be no propagation of
light"

* http://en.wikisource.org/wiki/Ether_..._of_Relativity

Harald

On Mon, 25 Jul 2011 19:23:30 -0500, Tom Roberts wrote:

Tom Adams wrote:
Maxwell never answered the question "constant with respect to what?".

He never had to -- his theory was based on a unique aether frame,

Really? Where does this aether frame appear in Maxwell's equations?

And if they do appear, why do we still use Maxwell's equations since
we're so smart now and know that there is no aether?

"Marvin the Martian" wrote in message
...
| On Mon, 25 Jul 2011 19:23:30 -0500, Tom Roberts wrote:
|
| Tom Adams wrote:
| Maxwell never answered the question "constant with respect to what?".
|
| He never had to -- his theory was based on a unique aether frame,
|
| Really?

Yes, really, you ****ing moron.

On 7/26/11 7/26/11 - 9:50 AM, Marvin the Martian wrote:
On Mon, 25 Jul 2011 19:23:30 -0500, Tom Roberts wrote:
Tom Adams wrote:
Maxwell never answered the question "constant with respect to what?".
He never had to -- his theory was based on a unique aether frame,

Really? Where does this aether frame appear in Maxwell's equations?

Really. The equations known today as "Maxwell's equations" are ostensibly
similar to a SUBSET of the equations of his 1865 theory, but the meanings of the
symbols that appear in them are DIFFERENT. Those equations ARE NOT MAXWELL'S
THEORY. As I have said so often in this thread, electrodynamics has been
re-conceptualized since 1905, and the modern synthesis, called Classical
Electrodynamics, includes SR, Maxwell's equations, and additional ideas and
material (composition of velocities, constitutive equations, etc.).

You are unable to distinguish between the modern meaning of "Maxwell's
equations" and his original theory. in particular, Einstein's 1905 paper was
instrumental in showing that such a re-conceptualization was necessary. Until
you learn the difference you will remain mystified about these details.


And if they do appear, why do we still use Maxwell's equations since
we're so smart now and know that there is no aether?

Maxwell "lucked out" in that a subset of his equations have survived to this
day, in a COMPLETELY different context, while most of his theory did not. Of
course this all happened long after his death.


Tom Roberts

On Jul 24, 5:19*pm, Marvin the Martian wrote:
Damn it!!

Einstein did NOT derive the Lorentz transformation.

Lorentz derived the Lorentz transformation.

And both Lorentz and Einstein were patently wrong! Yours truly has
disproved SR up down and sideways! There is no maximum velocity of
light; there is no space-time variance near massive objects; twins
don't age differently no matter how far one of them travels; and the
mechanism of gravity is flowing ether, replenished by the 'hobo' ether
transported back into space by the photon trains being exchanged
between attracting bodies—not space-time variance. Any questions,
dunce? — NoEinstein —

On Jul 26, 3:46*pm, NoEinstein wrote:
On Jul 24, 5:19*pm, Marvin the Martian wrote:

Damn it!!

Einstein did NOT derive the Lorentz transformation.

Lorentz derived the Lorentz transformation.

And both Lorentz and Einstein were patently wrong! *Yours truly has
disproved SR up down and sideways! *There is no maximum velocity of
light; there is no space-time variance near massive objects; twins
don't age differently no matter how far one of them travels; and the
mechanism of gravity is flowing ether, replenished by the 'hobo' ether
transported back into space by the photon trains being exchanged
between attracting bodies—not space-time variance. *Any questions,
dunce? *— NoEinstein —

Distance doesn't transform in the whole universe.
If the train contracted from what end would it start?
The distance contraction is supposed to be local for the train and
global for what is around the frame. The whole universe is around the
local frame global.

But the contracting atom clearly doesn't make sense.
Relativity must be an appearence alone as you cannot shape the
universe by your own motion.