screams in ultraviolet

picked up the Bandit from the shop today. the work included welding a rattling exhaust header, etching/sealing the fuel tank, and replacing the inline fuel filter. there was a strong odor of gasoline when they started it up. i figured it was just a rich mixture from the carbs being sticky from sitting around a long time.

i rode it to campus, with an intermittent strong odor of gasoline, even after the engine warmed up. i probably should have pulled over to do a detailed second inspection sooner. in the parking lot on campus, i let it idle while inspecting the fuel line. i saw a steady trickle leaking from the brand new inline fuel filter, dripping onto the ignition wires and the hot valve cover.

keep calm and shut it the fuck down.

i'm very grateful that it did not catch on fire. when i called the shop back, they asked me if i could ride it back there. i barely suppressed yelling something like "are you fucking kidding me?!?" at them. to their credit, they diverted one of their tow trucks to pick up the bike in less than half an hour.

i am still very disappointed by this.

the Monster got its front end literally run over by a tow truck Sunday morning. hopefully it doesn't end up totaled -- there is extensive front end damage: right handlebar bent to vertical, etc. still calling various insurance companies. unfortunate that a motorcycle parked on the street can easily sustain over $1000 in damage from a careless car driver.

have not even read LJ in a few weeks. still catching up...

have also made the amusing discovery that some recreational embedded systems programming turns out to be relevant to my day job.

i apparently climbed a 5.10c last night. WTF.

also, we felt an earthquake that happened near Mineral, Virginia. unsurprisingly, we don't often feel earthquakes in Boston, but apparently the age and continuity of the bedrock on the eastern coast of the U.S. means it transmits earthquake energy quite far.

there was some trench-digging kind of construction work going on outside my office building. when the shaking started, i thought it was the construction: i looked out the window to see the arm of the backhoe shaking from side to side. after brief bewilderment at what sort of earth moving operation would need that kind of odd motion (and why they needed to do it with enough force to shake the building) i went back to work, only to hear a few minutes later that yes, there was indeed an earthquake. the arm of the backhoe was probably not shaking from side to side under the control of its operator, but due to a quite different sort of earth moving.

one of those wonderful winter days where the sky is a swirling otherworldly grey, shading seamlessly from low clouds to fog and mist to falling snow. (i may like the accumulated snowfall much less, later, but this sort of sky still amazes me and remains nigh-impossible to photograph.)

have experimentally confirmed that RealD 3D (TM) viewing glasses use circular polarizers, without using any specialized apparatus. method is an exercise for the reader. (i might provide hints on request.) i'm not sure i'm a fan of the projection technique, though.

a week or so ago, i finally got the Bandit repaired after it had been sitting parked and broken for months. total repair cost was more than 90% of the insurance valuation. damage summary: astoundingly bent handlebars from multiple people parking badly and knocking the bike over (the shop said that everyone was amazed that the handlebars hadn't broken given how badly kinked they were), dead battery, badly varnished carburetors, seized front brake...

today, i found out the hard way where the fuel tank reserve level is, by stalling on Fresh Pond Parkway. it took a while to diagnose, because there are so many other things that habitually go wrong with this bike that simply running out of fuel was not near the top of the list. there's no fuel gauge or warning light either.

( gory details )

(no, i have not drunk enough rum to drown a dozen men...)

there is something very satisfying about literally feeling Newtonian dynamics -- particularly angular momentum -- in action in a simple physical system. i've been experimenting with meteor hammers (Chinese martial arts weapon that consists of a rope with a spherical weight at each end) on and off for a while. after having seen video of an acrobatics troupe performing some spectacular tricks with meteor hammers, i tried to replicate some of the simpler motions. one of these was revolving the weights overhead in a horizontal circle with the rope tensioned straight, somewhat like a helicopter rotor.

starting out by grasping the rope with its midpoint in one hand and swinging the weights in a horizontal circle overhead typically means the rope starts twisting up, and the weights orbit directly next to each other. achieving any significant speed requires a large horizontal force to maintain the centripetal acceleration. alternating hands caused the twists to stop forming, but the weights to remain close together, maybe separated by 15 degrees or so in their orbit. eventually i learned to use one hand to speed up or slow down an individual weight (by applying force to the rope near but not at its midpoint) while using the other hand near the midpoint to keep the weights in position. when the weights opened up in their orbit so they were opposite each other in the circle, i felt a most amazing thing: the horizontal force on my hands suddenly dropped to nearly zero, and the ordinarily very flexible rope began to act like a rigid object, needing only a tiny amount of applied force to offset gravity and air drag.

if i had enough space to practice in, i think i could have launched it upward, spinning like a flying disc, and caught it as it came back down. it is probably one of the simplest systems demonstrating angular momentum: two equal masses orbiting circularly around their barycenter, held together by rope tension.

for my main practice set, each end weight is (glass marble in a knot similar to a monkey's fist knot) approx. 30 grams, distance between centers of mass is approx. 72cm. i made a set with 75 gram end weights, but at any usable speed, being accidentally struck with it was very painful.

coffeekitty: C lets you DO that??

me: Remember when the pointer was sliding past the array bounds and I said "Goodbye!", and you were like "NO WAY!", and then I was all "We pretended we were going to segfault you." That was great.

interesting phrase of the week: "epistemic community". i think it's not a terribly new concept, but the wording amuses me.