Saturday, January 22, 2005
I would further note here, a fact which seems to get little play in most popular accounts of the Summers remarks, that Harvard offers tenure to approximately 25 people a year: even if we assume that the genetic differences between the quantitative ability of men and women are well understood, empirical research suggests that they are IN NO WAY large enough to explain the distribution of women and men among the Harvard faculty.
Thursday, January 20, 2005
Friday, October 22, 2004
Friday, October 08, 2004
It turns out that although complicated in the realm of popular culture, there's an old chestnut which makes the rounds something to the effect that physics can't describe a curveball, the mechanics of the breaking pitch has been well understood for at least 200 years. At it's heart is something called the Magnus effect (see here for some neat pictures and more on this topic): a description of what happens to a spinning entity as it travels through a fluid.
The basic idea is this. Because a baseball is relatively large relative to air molecules it is imperfectly aerodynamic: air tends to separate on the upstream side of the ball and recombine on the downstream. This means that, for a nonspinning ball moving forward through the air, a high pressure zone is created on the upstream and a low pressure one on the downstream. This pressure difference acts to slow the ball's forward progress and to make it fall to earth much more rapidly than it otherwise might.
The trick to throwing a breaking pitch is to throw the ball and set it spinning at the same time. When that happens the boundary layer of air around the ball is disturbed. No longer does air separate at the front of the ball and the currents recombine exactly at the back. Instead the location where the air recombines is shifted (if the ball has back spin the location is shifted down, if top spin it's shifted up). A incomplete but still possibly useful explanation of why this might be important has routinely been used to explain how an airplane flies. The idea is, basically, that the in the case of, for example, backspin the recombination point is shifted down. This means that air that travels over the top of the ball will travel relatively faster (think of it as getting the 'kick' from the spinning ball) than air that travels below, in the process becoming slightly less dense (think of it getting stretched) and hence giving the ball a small amount of lift. To make the ball sink or move sideways is a analogous.
If you think about it this way it seems like it might be tough to make a ball curve, but it turns out that big league pitchers and serious pitching machines can make a ball move something like 18 inches off the path it might otherwise take as it travels from the mound homeward.
Wednesday, October 06, 2004
UPDATE - There's been a sizable amount written at many other political sites about the line that was undoubtedly expected to be one of the Republican slogans as we come down the home stretch. After asserting that, in his capacity as president of the Senate he was on the hill most Tuesdays, Cheny remarked, "The first time I ever met you was when you walked on the stage tonight", suggesting, of course, Edwards hadn't been showing up.
This is a lie on two levels.
1. Cheney had met Edwards on more than one prior occasion and the pictures exist to prove it (follow this link to Tim Noah at Slate or this to Kevin Drums entry on the topic).
2. Over the last several years at the Senate Cheney has presided over only 2 of a possible 129 Tuesdays. This, as it happens, is as many days as Edwards has presided.
Tuesday, October 05, 2004
For those who might not remember, BCCI was a highflyer in international finance for about a decade starting in the early 80's. Founded by a Pakastani businessman, they invested extensively in (among other things) american politicians, creating a strong network of ties on both the right and the left. In the late 80's, though, BCCI started cropping up in all sorts of law enforcement operations: they laundered money from a dictator here, from a drug lord there. In work which was potentially damaging to his own political propects (it was over the objections of many democratic insiders) Kerry led Senate hearings, found a venue for persectution in New York with the sympathetic DA Robert Morgenthau and played a critical role in breaking up the bank both at home and abroad.
In retrospect BCCI was sort of a financial super store for things criminal. At significant potential risk to his own political future, and years before the general public seemed to care really strongly about terrorist financing, John Kerry played the most important role in breaking it up.