## September 24, 2009

### At least it's not figgy

1. Okay - frustrated people are requesting an explanation.

Heisenberg Uncertainty Principle - position & momentum can't both be determined at the same time to within a certain degree of precision.

Thomson - came up with the "plum pudding" model of the atom before they knew about nuclei. Electrons embedded in a cloud of positive charge.

Schrodinger's equation - wave equation for energy states of an electron, among other things. The first problem usually solved in a QM class is the problem of an electron trapped in a potential well.

Schrodinger's cat - an analogy for the quantum superposition of states - cat in the box may or may not be dead, not known until observed. In my opinion, the dumbest physics analogy ever, but I haven't come up with another one.

Einstein: some measurements depend on perspective (relativity)

Pauli Exclusion Principle - no two identical fermions (e.g. electrons and protons) can occupy the same state at the same time.

Bohr: among his many contributions, defined operators that commute or don't. Commute means that they can be applied in any order and the result is the same. For example, adding 2 to something, then adding 4, is the same as doing it the reverse order. However, adding 2 then dividing by 2 doesn't commute.

Hope this helps??

E.P.

p.s. I went to grad school with a woman from Hamilton, Ohio and we were always asking her for a ride to school. If you get the joke, you shouldn't be reading this - you should be finishing your thesis. You can't mooch off your adviser forever, though many have tried.

2. p.p.s. Thanks, Joe!