# Re: Quantum Mechanics

From: Loren Haarsma (lhaarsma@calvin.edu)
Date: Mon Apr 16 2001 - 16:09:29 EDT

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On Mon, 16 Apr 2001, John W Burgeson wrote:

> I've been asked to explain QM in 15 minutes to a seminary class Thursday
> beginning with Aspect's experiment in the early 80s as reported in NATURE
> on page 671 of an unidentified issue in about 1985 or so (the prof had a
> copy which interests him).

If you're going to talk about the spooky consequences of QM, it might be
a good idea to spend 2 or 3 minutes to motivate QM -- how it solves some
problems of classical physics.

E.g. According to classical physics, if you have an electromagnetic field
of frequency "f", you can add or absorb any amount of energy you want from
it. According to QM, energy must be added or absorbed in quanta of E=h*f.
(This is a good thing. Otherwise, under classical physics, a finite box
at a finite temperature would have an infinite amount of electromagnetic
energy inside it.)

E.g. According to classical physics, an electron oribiting a nucleus in an
atom should radiate away its energy, and thereby destroy the atom, in a
fraction of a second. According to QM, there are stable bound electron
states where the electron has angular momentum L = n*h, where n = some
integer. (Obviously, this is a good thing.)

E.g. QM explains why some electrons in electrical conductors are free to
move from atom to atom. (This is a good thing if you want to build
electric circuits.)

And it also might be worth mentioning the correspondence principle -- that
QM gives the same predictions as classical mechanics for "everyday"
objects.

```---
Have fun explaining the "spooky" stuff....  :-)
Loren Haarsma
```

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