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Re: [Phys-l] Force on a charged particle from a magnetic field



On 11/28/2006 12:31 PM, Kilmer, Skip wrote:
Isn't this the sort of question Einstein was asking in 1904?

Yes.

He published the answer in 1905.
"Zur Elektrodynamik bewegter Körper"
http://www.physik.uni-augsburg.de/annalen/history/papers/1905_17_891-921.pdf
or, translated:
"On the Electrodynamics of Moving Bodies"
http://www.fourmilab.ch/etexts/einstein/specrel/www/


=====================================

There is one slight pedagogical problem here: The 1905 paper has
a formal and mathematical part, which is OK, but the paper also
contains an intepretation in terms of rulers that can't be trusted
and clocks that can't be trusted (Lorentz contraction and time
dilatation).

The intuitive and pictorial interpretation did not come along until
a year or so later. Poincaré and others were involved. This
involves invariant (proper) length and invariant (proper) time,
spacetime diagrams, and all that.

Einstein adopted the spacetime approach when it became available,
and relied on it in all his future work, including the development
of general relativity.

So the pedagogical question is, why Why WHY is it still standard
practice in introductory courses to bedevil students with rulers
that can't be trusted and clocks that can't be trusted?
http://www.av8n.com/physics/odometer.pdf

Why not just start with the spacetime approach, which is easier
to understand, easier to depict, easier to teach, easier to
learn, more consistent with things we've already covered (e.g.
vectors and trigonometry), more sophisticated, more powerful,
and more extensible?
http://www.av8n.com/physics/spacetime-trig.pdf


Just because Einstein came to relativity the hard way doesn't
mean we need to do the same.

Pedagogy need not recapitulate phylogeny.