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Hi folks,I'm trying to solidify my QM so I'm studying Liboff's QM text 4th Ed. On page 23 he asks to show that A = x - pt/m satisfies the equation (@ = partial sign) @A/@t = -{A,H} where {A,H} is the Poisson bracket of A and H. Here H is the Hamiltonian. I tried simple substitution using Hamilton's equations but it didn't seem to work.

But you or the book forgot to say that dA/dt = 0

For a free particle moving in one dimension, show thatA = x - pt/msatisfies the equation@A/@t = -{A, H}so that it is a constant of the motion.

+1 Lightarrow. if A is conserved dA/dt =0 - and even I can follow the rest...

Your response is not the answer because you assumed that which was to be proven....I know how to solve it now...

Quote from: Pmb on 31/03/2013 21:32:22Your response is not the answer because you assumed that which was to be proven....I know how to solve it now...It's your way of saying "thank you for the hint!" ? []

A friend of mine e-mailed me and reminded me it was a free particle and thus dp/dt =0.

Quote from: Pmb on 01/04/2013 21:57:01A friend of mine e-mailed me and reminded me it was a free particle and thus dp/dt =0. And the text of the exercise don't remind it? Weird.

It's known as a brain fart. Give me a break. I don't screw up all that often. Plus and I live with terrible constant nagging pain that distracts me which messes up my concentration big time.

Quote from: Pmb on 04/04/2013 16:18:36It's known as a brain fart. Give me a break. I don't screw up all that often. Plus and I live with terrible constant nagging pain that distracts me which messes up my concentration big time.I didn't mean to make a critic to you, was just curious.