Natural Science Forum / Physics / Relativity / July 2009

Troll.

 I have been reading messages in this group for some time now, hoping to
 learn about relativity.

 ===================================
 With a name like that you should be successful.

With a name like that you should be successful.
There are clearly more sound arguments against Lorentz's contraction
theory than there are for it. It seems little different from Einstein's
expansion
theory.

This is a TERRIBLE place to learn anything, except perhaps that there
are a lot of people out there with delusions of grandeur and rather
serious mental deficiencies.

To learn much of anything requires a good textbook, and sufficient
dedication on your part. For SR, I suggest:

    Taylor and Wheeler, _Spacetime_Physics_.

Not at all! SR is one of the cornerstones of modern physics, and among
real scientists there is no controversy at all. It's just that most of
the contributors around here don't understand much of anything,
certainly not modern physics. This is one of the reasons that this is a
TERRIBLE place to learn anything.

You OBVIOUSLY have not actually read much of the scientific literature,
or any good textbooks on the subject. Your claim here is completely wrong.

Tom Roberts

Most would suggest Space-time physics by Wheeler and Taylor.  Great book but
the one I suggest is a text on classical mechanics that includes relativity
as well:
http://www.amazon.com/Introduction-Classical-Mechanics-Problems-Solutions/dp/052
1876222

Not at all.  It is a mainstay of modern physics.

Most cranks don't.  Most non cranks do think it is correct.

If you believe that you obviously have not read or understood the posts by
the non cranks eg see
http://arxiv.org/abs/physics/0110076,
and an ancient, but I still think excellent post by Tom Roberts
http://groups.google.com/groups?hl=en&lr=&c2coff=1&selm=54jfst%24glp%40ssbunews.
ih.lucent.com

That is incorrect.

LET, while very similar mathematically is based on entirely different
physical assumptions.  Those physical assumptions are at odds with other
theories such as QED.

Maybe there is not as well.  Unless one is unambiguously detected no one can
say.  But like the tooth fairy most would suggest the fact it has neverbeen
found strongly supports it does nt exist.  It does not prove it of course -
science can never prove negative statements like that just as no one can
prove the tooth faity does not exist.

Thanks
Bill

Here are some links with basic info in them.

Study these (or if you already know all about it) try to
help them find a solution to the false lack of simultaneuety
as their minds have burned out to such a degree that they
can't think for themselves....

http://www.btinternet.com/~j.doyle/SR/sr7/sr7.htm

http://quantumrelativity.calsci.com/Relativity/Chapter2.html

http://www.thedatasphere.com/Relati~1.htm

http://www.upscale.utoronto.ca/GeneralInterest/Harrison/SpecRel/SpecRel.html

Spirit of Truth

Einstein's silly theory is nothing but a variation of LET. Einstein was a
hoaxer and a good salesman. There is absolutely NO evidence that light speed is
always c. In fact, variable star curves PROVE that light travels across space
at a wide range of speeds relative to our planet. It may end up at c when it
enters the Earth's 'EM sphere of influence' or its atmosphere.
Light is particulate and ballistic. The particles themselves oscillate
intrinsically. Light loses speed as it travels...hence the cosmic redshift.

Big Bang Big Bull!

And by the way, the principle of relativity was around long before
Einstein....so was E = mc^2........so don't even try to learn Einstein's
version of relativity. It's a load of crap from start to finish.

Henry Wilson...www.users.bigpond.com/hewn/index.htm

........putting Physics back into Phairyland...

Do not worry. You are in the same position with:

Dork van der Brothel (the biggest idiot you will never come accross)
Uncle Ben (an old man who thinks age brings knowledge)
PD (A Ph. D without the h. as you can see)
Bill Hobba (a shares trader who is a relativist when shares do not
move)
Eric Gissa (a college school dropout I was told)

Only Tom Roberts knows relativity hare but he keeps many things for
himeslef and never gets to the bottom. A few other know a little. I
know a little.

Both SR and LET are incomplete theories. A new theory of relativity
called Improved Relativity Theoory (IRT) is a complete theory of
relativity. IRT includes SRT and LET as subsets. However, unlike SRT
and LET the equations of IRT are valid in all environments, including
grvaity. A full description of IRT is available in the following link:
http://www.geocities.com/kn_seto/2008irt.dtg.pdf

Ken Seto

Although this group is an extremely very bad example of politeness,
the jokes are mostly concerning those who are beyond hope of ever
learning (from watching them for many years).

Technically there never was a "Lorentz's ether theory", and Lorentz's
theory is simply that of Einstein plus an ether concept - there is NO
difference in practice. Similarly, Minkowski's Spacetime theory never
really existed either.

It was just a model (not a prediction) and the essence of Maxwell's
theory was conserved in SRT:

"We will raise this conjecture (the purport of which will hereafter be
called the ``Principle of Relativity'') to the status of a postulate,
and also introduce another postulate, which is only apparently
irreconcilable with the former, namely, that light is always
propagated in empty space with a definite velocity c which is
independent of the state of motion of the emitting body. These two
postulates suffice for the attainment of a simple and consistent
theory of the electrodynamics of moving bodies based on Maxwell's
theory for stationary bodies."
- http://www.fourmilab.ch/etexts/einstein/specrel/www/

Harald

Cart before the horse.

You are worried about the assumptions being plausible and arguable
PRIOR to comparison with experiment.

This is backwards.

In science, the assumptions are not evaluated on their own. They are
developed into measurable consequences that fall uniquely from those
assumptions, and in particular consequences that are different than
what would be obtained from other assumptions.

Then those measurable consequences are measured in experiment. This
unambiguous comparison is the ONLY THING in science that serves as the
validation (or invalidation) of the assumptions.

Not arguments.
Not plausibility.
Not connection with familiar reality.

PD

2+2=5 wrote on Fri, 03 Jul 2009 23:34:15 +0000:

I doubt.

Most of non-scientists think so.

This is sad.

Einstein's theory? Do you mean SR? Then there is no serious argument
against SR.

Lorentz himself praised both Poincaré and Einstein by improving him when
developed SR.

But science is about that can be emasured/proved, not about one can
imagine.

This the USENET, not the real world; the same type of venue as the
Jerry Springer show or a trailer park. So, you shouldn't expect much
more than the equivalent of creationists or flat-Earthers hanging
around.

In fact, there is little convtroversy at all. The main reason is that
-- unlike what you may gather here (or, for that matter in many
mainstream accounts) the differences between the relativistic and non-
relativistic treatments of electromagnetism are both (a) small, but
(b) stark and clear-cut where they actually differ.

Here's the scoop. The relavitivity principle of "non-relatividtic"
physics is that based on Galileo's principle of relativity. In it, the
only absolute speed is infinite. A round-about way of saying the same
is that "simultaneity" is absolute (simultaneity is the quality of
being simultaneous). In relativistic physics, the absolute speed is
finite (which makes the name of the paradigm ironic). Infinite speed
is relative, as is simultaneity.

This comes back to haunt Maxwell. In the beginning (1861;
http://federation.g3z.com/Physics/index.htm#Maxwell1861) Maxwell posed
field theory as that based on a background medium. This medium in his
1861 and 1864 treatments he regarded as isotropic. The reason he was
forced to this assumption is that electromagnetism supports waves
travelling at a fixed speed. His only out was to equate "fixed speed"
with "fixed speed with respect to some medium" -- precisely because
Galilean relativity has no finite absolute speed.

It was also for this reason he expressed skeptism of any such thing as
a bona fide vacuum.

The Poincare form of relativity has a finite absolute speed.

So, let's define a few things and take a serious point of departure
from Maxwell and Faraday and their contempraries. Their point of view
was to say "there's a medium, it is made out of more basic stuff."
This is begging the question. Our point of view is this: "there is
stuff, it is made out of media. Media is the fundamental undefined
term, not 'corpuscles' or 'atoms'. Everything else has to be described
in terms of the behavior of these elementary systems under the action
of Galilean (or Poincare) relativity".

Our tact is this: a medium is anything described by the constitutive
relations of a Lagrangian field theory. If the Lagrangian respects
rotational symmetry, then the medium is ISOTROPIC. If it also respects
symmetry under Galilean transformations, then it is a (Galilean)
vacuum. If, on the other hand, it respects symmetry under Poincare
relativity (which meaans it remains invariant under the Lorentz
transformation), then it is a relativistic vacuum.

The punchline is this: there is a single unified treatment of
isotropic media for the electromagnetic field that spans the gap
between relativistic and non-relativistic theory. It is here that (a)
the commonality and (b) the differences show up the most clearly.

The electromagnetic field is a Lagrangian field theory. Its
configuration is described by the vector potential A, the scalar
potential phi; and a certain set of combinations of gradients taken of
these potentials: E = -grad phi - @A/@t (where @ denotes partial
derivative operator) and B = curl A.

The dynamics are governed by a Lagrangian L. From it, the conjugate
fields can be defined: D = @L/@E, H = -@L/@B, J = 2L/@A and rho = -@L/@
(phi).

This is a common form of a wide range of field laws. These partial
differential relations are the most general form of the constitutive
law for any Lagrangian formulation of electrodynamics. Specific models
are then governed by the symmetry principles governing the different
types of media.

An isotropic medium is one respecting rotational symmetry. This means
the Lagrangian is a function only of those combinations of field
components invariant under rotation. We also assume here, and below,
that there is no explicit dependence of L on the potentials (this
feature is called "gauge invariants" and was first described in
Maxwell's 1861 treatment).

Of the remaining fields, B and E, the only rotation-invariant
combinations are I1 = B^2/2, I2 = B.E, I3 = E^2/2. The Lagrangian is
then a function L = L(I1,I2,I3).

This places a severe restriction on the possible forms for an
isotropic medium. Out of this, one can DEFINE the constitutive
coefficients (Maxwell introduced them ad hoc, by contrast):
  permittivity?: epsilon = @L/@I3
  permeability: mu = -1/(@L/@I3)
and a third coefficient, which Maxwell mixxed:
  theta = @L/@I2.

As a result, after substitution, one finds the following constitutive
laws:
  D = epsilon E + theta B, H = B/mu - theta E.
This is the most general form of a constitutive law for an isotropic
medium. The coefficients must satisfy the relations
  @(epsilon)/@I2 = @(theta)/@I1, @(epsilon)/@I3 = (1/mu)^2 @(mu)/@I1,
@(theta)/@I3 = (1/mu)^2 @(mu)/@I2
and may themselves be functions of I1, I2 and I3.

This formulation covers BOTH the relativistic and non-relativistic
media. It's here where the two forms become distinct.

First, in BOTH the relativistic and non-relativistic versions of the
constitutive law, the property of "isotropy" generally only holds in a
fixed frame of reference.

Maxwell recognized this early on and so he introduced a velocity
vector G (which today is nearly forgotten) to express the velocity of
this distringuished frame of reference relative to the observer. The
constitutive relations above then only hold in the distinguished frame
of reference.

When going over to a moving frame of reference, one has to apply the
transformations for velocity change. Both the relativistic and non-
relativistic forms are captured by the following transformations:
  Dn -> Dn, En -> En, Bn -> Bn, Hn -> Hn where n is the component
parallel to the velocity change
  Ep -> (Ep + v x Bp)/R, Dp -> (Dp + alpha v x Hp)/R
  Bp -> (Bp - alpha v x Ep)/R, Hp -> (Hp - v x Dp)/R
where p denotes the component perpendicular to the velocoty change and
v is the velocity change, with R = root(1 - alpha v^2).

For relativistic theory alpha = (1/c)^2. For non-relativistic theory
alpha = 0.

When substituting into the constitutive laws to transform from the
"medium-fixed" frame to the "moving frame" the result is the following
set of constitutive laws:
  D + alpha G x H = epsilon (E + G x B)
  H - G x B = mu (B - alpha G x E).
Here, I'm setting theta = 0 and ignoring its effect for the sake of
simplicity. Theta would be included by replacing D by D - theta B and
H by H + theta E.

Now, Maxwell could not get away from having a G vector because in non-
relativistic theory (alpha = 0), for any non-zero G, the constitutive
laws are NOT the same as in the fixed frame of references.

HOWEVER ... in relativistic theory, since there is a finite absolute
velocity (c), then the constitutive laws reduce back to the fixed-
frame precisely when
  alpha = mu epsilon.

The condition alpha = mu epsilon then defines the "vacuum" (keeping in
mind that we DEFINED a vacuum as any medium that is both rotationally
and velocity invariant).

The general solution for (D,H) in terms of (B,E) is something along
the lines (and I'm doing this off the top of my head, so I might have
a few sign errors):
  D = epsilon E + epsilon (V^2 - c^2)/(G^2 - c^2) G x (B - alpha G x
E)
  B = mu H + epsilon (V^2 - c^2)/(G^2 - c^2) G x (E + G x B)
where V denotes the wave speed of the medium V = 1/root(mu epsilon).

The relativistic vacuum is precisely where the wave speed V matches
the invariant speed: V -> c. As you can see, when you take the limit
(as long as |G| is not equal to V), then terms with G drop out and the
"velocity G becomes superfluous".

Thus:
(a) non-relativistic electromagnetism has no "vacuum", but only a non-
relative isotropic medium
(b) relativstic electromagnetism has BOTH a "vacuum" and a non-
relative isotropic medium. The former is a special case of the latter
when alpha = mu epsilon.
(c) nothing in the real world is actually a vacuum (not even outer
space), so the distinction is somewhat vacuous.

If you set alpha = mu epsilon (or V = c) and solve the above equations
for (D,H) you will get D = epsilon E; B = mu H for ALL values of G.

These 2 equations are called the Lorentz relations.

However ... this is an interesting point that has been missed by
everyone: this does NOT actually always occur. If the medium is moving
at a speed |G| given by mu epsilon G^2 = 1, then taking the limit
alpha -> mu epsilon will NOT yield the Lorentz relations.