Thursday, April 19, 2012

Just Skip Precession

Precession is an effect angular momentum has on a rotating object. It's pretty neat stuff because its consequences seem so strange. It's why tops appear to wobble and boomerangs come back.

A lot of people bring up precession when discussing seasons. This is because the earth is rotating, so it too experiences precession. However, this is not the cause for seasons but a consequence of the cause--tilt. Because the earth is tilted, the length of the day changes as the earth goes around the sun. The length of the day changes the amount of light the earth gets; the amount of light the earth gets affects temperature, an effect we call seasons.

The connection between light absorption and temperature is really important but doesn't get much emphasis. To understand global warming, you first have to grasp this concept. Yet for some reason, precession, an obscure fact related to angular momentum, gets thrown in while explaining seasons. Sure, it's a consequence of tilt, which is the cause for seasons, but it just confuses someone who is trying to grasp the concept that the earth is sideways.

Then, on top of it, people try to use tops as a metaphor to explain precession. Tops precess at about 1 Hz, unlike Earth, which precesses at 8.11012998 × 10^-11 Hz. So then people get confused because you just told them the earth is sideways and then tossed in counter-intuitive facts about angular momentum with a confusing metaphor to explain them. Just skip precession. You can cover it when you discuss momentum. If you're not discussing angular momentum, it's not important.

Sunday, April 15, 2012

Classical Music Riots

A couple months ago, I listened to a Radiolab episode on "Musical Language." One of the things they talked about was how music affects the brain--in particular, Igor Stravinky's Rite of Spring. Apparently, novel sound patterns can trigger the release of dopamine in the brain. In small doses, dopamine is pleasing. However, a large enough disruption can cause hallucinations and psychosis. This has happened before, many times, because of classical music. Here are a few:

La muette de Portici

I'm not sure whether this is the exact portion that triggered a riot or not. This is the oldest one on the list. In 1830, a portion of the piece involving patriotic and revolutionary themes started a riot that led to the Belgian Revolution, ceding Belgium from The Netherlands.

Benvenuto Cellini

At its premiere, it started a riot and was deemed impossible to perform by the musicians who took part.


Strauss based Salome on a play written by Oscar Wilde. For years, it couldn't be performed in London. Most notorious is the final portion of The Dance of the Seven Veils, where Salome kisses the severed head of John the Baptist.

The Rite of Spring

This was the first of these that sounded familiar to me. It begins deceptively peacefully, but by 3:35, it takes a turn for the awesome. A name like "Rite of Spring" sounds so happy--Vivaldian, if you will. The premise of the play, however, is a young woman dancing herself to death, and the choreography and music reflect this.

During the premiere, the audience was split between loving the piece and hating it. Fist-fights started in the aisles, followed by a full on riot.

Musica Futurista

Futurism was a movement in Italy that glorified ideas of the future, like speed and technology. In particular, futurist musicians like Pratella rejected tradition and emphasized experimental sounds.

Four Organs

People actually screamed for this to stop. "One woman walked down the aisle and repeatedly banged her head on the front of the stage, wailing 'Stop, stop, I confess.'" It's pretty damn cool, honestly.