Re: [Phys-l] Teaching Special Relativity

["Bob Sciamanda" <treborsci@verizon.net>]

Just as the physics of a moving photon clock explains (below) the mechanism 
which gives it a longer period, it is the assertion of the relativity 
principle that there will be a corresponding physical mechanism behind the 
slowing of any well constructed moving clock.

It is further asserted that the same principle applies to all "relativistic 
effects" in the behavior of moving objects.  This is the very essence of the 
relativity principle.  After all, Einstein's 1905 relativity paper was 
entitled "The electrodynamics of moving bodies".

Even before 1905 - Lorentz, Fitzgerald, et al argued that a real shortening 
of a moving rigid rod follows from Maxwellian electrodynamics. Their 
argument centered around the real weakening of the E field of a moving 
charge in the direction of its motion (its spherically symmetric field 
becomes "squashed" in its forward direction).  This is a real effect of 
Maxwellian electrodynamics, with real consequences - it is not merely a 
projection or merely an appearance .

For Lorentz this effect depended on the absolute velocity of the observed 
object - ie, relative to the aether.  Einstein's leap was the bold assertion 
that the velocity of an observed charge in Maxwell's equations is relative 
to the observer - ANY inertial observer.

PS:
J.S. Bell (yes, THAT Bell) outlines the Lorentz approach in "How to Teach 
Relativity", Progress in Scientific Culture, Vol 1, summer 1976.  This paper 
is included in the paperback collection by Bell: "Speakable and Unspeakable 
in Quantum Mechanics", Cambridge, 1987.

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
treborsci@verizon.net
http://mysite.verizon.net/res12merh/

--------------------------------------------------
From: "Bob Sciamanda" <treborsci@verizon.net>
Sent: Saturday, July 04, 2009 8:35 AM
To: <phys-l@carnot.physics.buffalo.edu>
Subject: Re: [Phys-l] Teaching Special Relativity

> The driving essence of the principle of (special) relativity is that 
> physics is the same in all (inertial) reference frames.  This means that 
> measured quantities are related by the same quantitative equations.  This 
> is achieved by (Lorentz) transforming the measurables in the invariant 
> equations.
>
> For example in the case of the simple bouncing photon clock, the physics 
> is simply that time of travel = distance traveled, divided by the frame 
> invariant speed "c".
>
> Both the "proper observer"(traveling with the clock) and the "stationary 
> observer" use this same physics to describe the observed reality.  But 
> when you compare the calculations of the two observers, it will be 
> apparent that the stationary observer calculates the time of travel as a 
> larger distance divided by the same speed "c".
>
> The measurable quantities appearing in the physics equation are the 
> physicists "reality"; and these realities change numerical values (through 
> Lorentz transformations) when measured in different reference frames, the 
> physics (equation) remaining the same.
>
> This is the same relativity which describes the E and B components of an 
> electromagnetic field when viewed in different frames.  There is no 
> universal "proper" frame in which E and B are measured as their "real" 
> values. (Is it that we want to resurrect the "aether frame"?)
>
> Bob Sciamanda
> Physics, Edinboro Univ of PA (Em)
> treborsci@verizon.net
> http://mysite.verizon.net/res12merh/