Weekend Reading: Robert Allen on Japan

Special Relativity is literally baked in the cake of Maxwell's Equations: John Stewart Bell: How to Teach Special Relativity, Speakable and Unspeakable in Quantum Mechanics https://books.google.com/books?isbn=0521523389: "We have followed here very much the approach of H. A. Lorentz. Assuming physical laws in terms of certain variables (t, x, y, z), an investigation is made of how things look to observers who, with their equipment, in terms of these variables, move...

...It is found that if physical laws are Lorentz invariant, such moving observers will be unable to detect their motion. As a result it is not possible experimentally to determine which, if either, of two uniformly moving systems, is really at rest, and which moving. All this for uniform motion: accelerated observers are not considered in the ‘special’ theory.

The approach of Einstein differs from that of Lorentz in two major ways. There is a difference of philosophy, and a difference of style. The difference of philosophy is this: Since it is experimentally impossible to say which of two uniformly moving systems is really at rest, Einstein declares the notions ‘really resting’ and ‘really moving’ as meaningless. For him only the relative motion of two or more uniformly moving objects is real. Lorentz, on the other hand, preferred the view that there is indeed a state of real rest, defined by the ‘aether’, even though the laws of physics conspire to prevent us identifying it experimentally. The facts of physics do not oblige us to accept one philosophy rather than the other.

And we need not accept Lorentz’s philosophy to accept a Lorentzian pedagogy. Its special merit is to drive home the lesson that the laws of physics in any one reference frame account for all physical phenomena, including the observations of moving observers. And it is often simpler to work in a single frame, rather than to hurry after each moving object in turn.

The difference of style is that instead of inferring the experience of moving observers from known and conjectured laws of physics, Einstein starts from the hypothesis that the laws will look the same to all observers in uniform motion. This permits a very concise and elegant formulation of the theory, as often happens when one big assumption can be made to cover several less big ones.

There is no intention here to make any reservation whatever about the power and precision of Einstein’s approach. But in my opinion there is also something to be said for taking students along the road made by Fitzgerald, Larmor, Lorentz and Poincaré. The longer road sometimes gives more familiarity with the country...