Saturday, March 07, 2009

QM at Southampton

Down to Southampton University this morning for the first OU tutorial for SM358 Quantum Mechanics. There were eight of us plus the tutor: seven men ranging in age from mid-40s to 60+ and one woman. Amongst the men there were three Nigels - I consider this statistically significant.

The tutorial was Schrödinger equation-centric. At one point we discussed the wavelength of a neutron travelling at a certain speed (kms per second): it came down to a few nanometres. I raised as a discussion point whether the neutron wavelength has the same physical significance (as a parameter within the Ψ function) as more physically obvious wavelengths, as for example those seen in radio waves, where we commonly talk about quarter-wavelength antennas and so on.

This example mixes up quantum and classical descriptions and I suspect I am just a bit muddled. However, we have not yet got to the part of the course where the classical description of an electromagnetic wave is recast as an ensemble of photons described quantum mechanically. Indeed, this may be out of scope of a first course entirely, so my sense of being on somewhat shaky ground is perhaps justified.

Clearly at some level neutron wavelengths have quantitative observables outcomes, as in diffraction by crystal lattices. However, I think my question was more fundamental than that.