Re: Comments on my FAQ page (was: What become...)

Koobee Wublee wrote:
I have comments on this paper, "What is the experimental basis of
Special Relativity?" written by Dr. Roberts and Mr. Schleif.
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#one-way%20tests

In section 3.5, Tests of the Principle of Relativity and Lorentz
Invariance, Dr. Roberts wrote the following.
"Einstein's first postulate, the principle of Relativity (PoR),
essentially states that the laws of physics do not vary for different
inertial frames."

A better way to state the principle of Relativity is that the laws of
physics do not vary for any moving observers.

That is not at all a "better way", because your "moving observers" is woefully undefined. Moreover, it is the projection onto an inertial frame that is an important aspect of this. Einstein's first postulate is quite explicit in referring to _coordinates_ (here "frame").


This principle is just a
subset of another more powerful principle, if proven valid, that all
observers obey the same laws of physics.

SR's first postulate limits its basic statements to inertial frames (which can be extended via mathematics to any system in flat spacetime). One needs a more general approach, like that of GR, to handle _ALL_ observers, because real observers live in the real world which cannot be accurately modeled as flat.


In another words, all
observers obey the same transformation.

No, that is not "other words", that is a completely different statement than "all observers obey the same laws of physics". Indeed, the same laws of physics do appear to apply to all observers, but there are MANY different transformations relating different observers' coordinates. Note it is not at all clear what observers "obeying" a transformation means -- transformations relate coordinate systems, and do not impose restrictions on observers that they must obey.


In section 5, Tests of the "Twin Paradox", Dr. Roberts pointed out
Haefele-Keating Experiment verifies SR time dilation. This is wrong.
SR predicts both parties would see the same time dilation depending on
the relative speed between them. Since this experiment indicates a
different observed time dilation, this experiment actually disproves
SR.

You really need to actually READ the page. For H&K it mentions _GR_, not SR. Yes, SR does not really apply to their experiment; that is, this experiment is outside the domain of applicability for SR. <shrug>

And SR "predicts both parties would see the same time dilation" _ONLY_ when both parties are at rest in inertial frames; for H&K that is manifestly not true.


In section 6, Tests of Kinematics Dynamics, Dr. Roberts wrote the
following.
"The two basic predictions of SR in this regard are that massive
objects will have a limiting velocity of c (the speed of light), and
that their "relativistic mass" will increase with velocity."
Please show how SR predicts this relativistic mass. If the equation (E
= m c^2) is invoked, please prove the equation is valid through math.

This is explained in any elementary book on SR, such as Taylor and Wheeler, _Spacetime_Physics_. The "relativistic mass" of an object relative to a given inertial frame is defined as:
RelMass = M/sqrt(1-v^2/c^2)
where M is the object's mass (aka invariant mass, aka rest mass), and v is its speed relative to the inertial frame in question.


In section 7, Other Experiments, Dr. Roberts wrote the following.
"SR predicts no ether but does predict that the speed of light in a
moving medium differs from the speed in the medium at rest, by an
amount consistent (to within experimental resolutions) with these
experiments and with the Fresnel drag coefficient."

Please show how SR predicts the speed of light in a moving medium
differs from the speed of light in the medium at rest.

This is really a combination of SR plus basic optics. The speed of light in an optical medium is c/n, where n is the index of refraction of the medium and this speed is measured in the rest frame of the medium. SR predicts one should use the Lorentz composition of velocities formula to obtain the speed of light in a moving medium.


Tom Roberts
.

Relevant Pages

  • Re: Proof that space is not really empty = eather
    ... Light traveling in space is not traveling in an empty medium, ... then light's velocity would be infinte but instead light's velocity is ... inertial frame we call the Eather. ... which comes from the Principle of Relativity: ...
    (sci.physics.relativity)
  • Re: Is the speed of light really constant ?
    ... That would be the usual interpretation, yes, that the moving source is ... >> observers seeing the first result, and others seeing the second ... ... >> the principle of relativity. ... Suppose that the two observers A and B synchronise their clocks by ...
    (sci.physics.relativity)
  • Re: Einsteins logic
    ... Maxwell's equations do not imply the existence of a medium. ... that imply an inertial frame. ... I suggest you acquaint yourself with a good treatment of Classical Mechanics ... of the laws of classical mechanics or relativity or perhaps even QM. ...
    (sci.physics.relativity)
  • Re: Why is the Speed Of Light Constant?
    ... Interestingly, the postulate Einstein used ... "Einstein's theory of special relativity results from two ... no matter what their relative speeds." ... "The speed of light is the same for all observers in uniform motion" ...
    (sci.physics.relativity)
  • Re: Why is the Speed Of Light Constant?
    ... "Einstein's theory of special relativity results from two statements -- ... no matter what their relative speeds." ... "The speed of light is the same for all observers in uniform motion" ... Einstein "derives" what everyone thought was a postulate, ...
    (sci.physics.relativity)