The weather usually doesn't cooperate

but the aurora page is nice to monitor -- just in case. The other day it reported a storm. A Kp of 7 meant it would be visible down into Illinois. There are a couple of places outside of town that have decent viewing possibilities.

Of course this was at 2 in the afternoon, so I decided not to drop everything and drive.

If you have clear nights, have a look at the page -- maybe there'll be a show. The first time I saw the aurora I was flying across the Atlantic, and the show was great, but distant. The second time they seemed to be almost straight up above us (about 43 degrees north). I haven't gotten bored yet.

Subjective and Objective

Long ago I came to the conclusion that all women were beautiful if you looked at them in the individual way God made each to be looked at—not demanding "identi-kit beauty." True, there are some with such deep infelicity of feature or character that I've never been able to apply that rule to them. But as a general rule it has seemed to work.

Some 15 springs ago I was waiting for a bus in front of the student union, where three young women were improving the vista with their presence. After a while I noticed that my eyes lingered longer on one of the three, and wondered why. All seemed equally cheerful, and the other two had more classical figures. One of the other two was displaying a good deal of herself, which is a sure-fire attention-getter. Still, I thought the first more attractive.

After a few minutes I realized why. The first woman resembled my wife.

Epicycles

Lubos Motl approved of and linked to this video about particle physics, s-matrix scattering, and a mention of string theory. You may have to back up and re-watch a few bits.

One of the bits describes the use of Feynman diagrams: Adding up all the various sub-processes that contribute to an overall interaction of some kind. A and B interact somehow to produce C and D, and all sorts of things can happen in the middle.

Yep, those are only a few. (See the video)

Each one of the diagrams represents a contribution that requires a messy integral to solve. With luck, the coupling at each connection is small, and the more and more complicated diagrams contribute less and less, so that you can reach "good enough" without too much pain. Without luck--and QCD doesn't have it--they can get bigger.

This formalism works beautifully for quantum electrodynamics.

The situation reminds me very strongly of epicycles. They work. "There is no bilaterally-symmetrical, nor eccentrically-periodic curve used in any branch of astrophysics or observational astronomy which could not be smoothly plotted as the resultant motion of a point turning within a constellation of epicycles, finite in number, revolving around a fixed deferent."

For Ptolemy's work he only needed to work with a few terms. But the epicycles don't show what's going on nearly as well as ellipses around the Sun. Of course the planetary interactions make our orbital calculations more complex than anything Ptolemy ever attempted, but to land probes we need way better precision than anything he ever attempted.

Lubos and O'Dowd think string theory is the tool we need to wrap up an infinite series of diagrams into a simple form: epicycles turn into universal gravitation and ellipses. I hope so, but I'm not sanguine about progress, given the lack of it so far, and the way supersymmetry is bound up with it. Supersymmetry itself seems rather epicyclic too: it lets you cancel out some divergences when trying to sum terms in perturbation theory. There's that business of adding up lots of finer and finer terms again.