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Re: [Phys-L] Spins First

I expect I have mentioned making a proton spin precession magnetometer many years ago which, given a fairly uniform undisturbed geomagnetic field, demonstrated the evanescent audio frequency e-m signal around 2 kilohertz which indicates the relaxation of the water sample in a small plastic bottle when the E-W magnetic solenoid field in it was removed. One of the few absolute measures of the geomagnetic field, as it happens. The idea of a spinning top precessing however over-simplified, was not in any way mysterious to my youthful mind.

Brian Whatcott Altus OK Indian Territory.

On 6/9/2014 2:24 PM, David Craig wrote:
I’m interested in people’s attitudes toward and experience with the “spins first” approach to teaching the junior-senior level quantum mechanics course, which seems to be gaining in popularity in some intriguing new textbooks (e.g. Mark Beck’s).

I get it: teach the distinctive features of quantum mechanics and attendant mathematics in the mathematically simple setting of a finite dimensional Hilbert space.

However, and here I reveal my opening bias, I am suspicious whether this is doing the good it purports to for the following reason: spin is typically initially perceived by students as mysterious and arbitrary. It’s “spin”, but there’s nothing spinning? And you can’t change it? Therefore, if it behaves in supposedly mysterious ways (i.e. quantum mechanically), so what? It’s weird and arbitrary anyway.

Comments? Experiences?

David Craig


PS. Full disclosure: I am once again contemplating my choice of textbook for quantum mechanics in the Fall. The last new one I tried was a disaster. Griffiths is well written in many ways and is about the right level for our students, but makes not the slightest bit of contact with experiment, is too slow to get properly into Hilbert space, and the solutions to all its problems are widely available. Hence, students tend to like it :-)




<http://web.lemoyne.edu/~craigda>