Every year since 1990, I have made a holiday card sending it to friends and family (a list of ~ 50). They have always been nerdy. I try and feature something about the physics I figured out in the year. This one is less upbeat than those in the past, but there is a reason for that ;-)


Doug

No math, no snarky puzzle.

Next Monday/Tuesday, Dec 26, a vacation week.
Monday/Tuesday, Jan. 2/3: Spinning the Interaction Story: Attracting and Repelling.

The spin 2 story unfolds much like that for spin 1. The stories are so similar, I want to take a step back and take a big picture view.

<Higgs digression>
QED works so darn well because Maxwell's theory works so well. In Maxwell's EM, action happens at a distance. Working instantaneously is a great approximation. It is only when people make refined measurements that something goes amiss. It is QED that provides the corrections. This can be done because the coupling constant for EM is small. A Feynman diagram is a visual way of keeping track of the corrections that need to be made to classical theory. Later on today, much will be said about the following three Feynman diagrams:

Oct 25, Gravity is a Mystery (in words, no equations)
Snarky puzzle: 

Is there a handedness to getting older? Is there a handedness to communication? If there is a handedness to either, how would that effect the arrow of spacetime?

The Back Story:
Clocks tick on. The universal march of time has no handedness. Put me in an isolation chamber and I will get older at the same rate as having Thanksgiving with the family. [clarification: as noted in the comments, there is no such thing as a complete isolation chamber, it is one of those unreachable ideals.]

Newtonian gravity binds us to this rock, while EM presents us with the messages from the heavens. The math of the EM is heavenly compared to Newtonian gravity. Let's review some of the flaws in that old but still useful approach to gravity.

A list of eleven steps to analyzing an action will be presented. I could have added one more, but then people might think I was giving up on my physics addiction. The method will be applied to Newton's theory of gravity in this blog. The Maxwell action will be up next. Only if something acceptable comes through the set of tools I construct will I do the third blog that would make the Newtonian action more like Maxwell.

Once an action is written down, the rest is calculation. To provide structure to the discussion, I have compiled eleven steps to look at. One could add more or use less. There is nothing sacrosanct about this eleven step implementation for analysis of actions. With these caveats in mind, these are the eleven steps.