meanfreepath

There are just some nice things about Shankar...

I recall from my class notes how, to prove that the wavefunction stays normalized once it has been normalized, despite time evolution, Griffiths had to do something rather long and nasty. But in Shankar, on p. 147, using an argument about the unitariness (? unity?) of the propagator for a Hermitian operator, this is basically a one-liner. Of course, Shankar has spent a great deal of time by Ch. 4 working out the mathematical underpinnings of QM whereas Griffiths starts out with wavefunctions right off the bat.

And then there's also the part on the same page where Shankar briefly discusses the Heisenberg and Schrodinger pictures of QM. This is just great: "Infinitely many pictures are possible, each labeled by how the basis is rotating. So if you think you were born too late to make a contribution to quantum theory fear not, for you can invent your own picture." (Shankar, p. 147)

Am thinking about propagators, and eigenstates, and spin...

I'm starting to post about physics. Am I becoming like