tired of the radiometer yet? last post. promise. some guy named reynolds finally explained the thing satisfactorily. reynolds as in reynolds number. there's a temperature gradient along the very edge of the vanes between the black side and the shiny side. when the gas hits this edge it gets a tiny extra kick towards the hotter black side. the vanes receive an equal kick in the opposite direction. qed. whew.
apparently the original radiometer vanes were made of a porous material. the gas gets dissolved in the vane and ejected on the hotter black side of the vane. this effect is real. but if you cool the radiometer it doesn't behave the way this theory predicts. and the killer is the thing still spins even if you use non-porous materials.
the radiometer needs to be in a partial vacuum in order to spin. if the gas is too dense then the tiny forces at play here cannot overcome air's viscosity. if it's in a perfect vacuum then again it stops spinning. apparently the rarefied gas plays an important role. the black side of the vane heats the gas which expands and pushes the vane. sounds good eh? this is the encyclopedia britannica explanation. it's wrong. the gas quickly reaches an equilibrium state with a temperature gradient and uniform pressure. no pressure difference - no spin.
the original explanation for how crookes' radiometer works was presented surprisingly enough by a guy named crookes who built the original device. he theorized the brand new theory of radiation pressure was the explanation. to get his paper published he had to get it past some guy named maxwell. as in maxwell's equations. incidentally it was maxwell's theory of radiation pressure. so maybe he didn't check the work as thoroughly as he should have. basically you have photons smashing into and imparting all of their energy and momentum to the dark side of the vanes. ergo we see sunlight push the black panes. right? wrong. photons bouncing off the shiny side of the vane deliver twice as much momentum. ergo the solar engine spins the wrong way.
also called a light mill or a solar engine. mine has four black and green(!) panes balanced on a needle in a glass bulb. it's a kinda neat toy. especially to physicists. what makes it spin? there are more valid seeming explanations than for why an airplane flies. but when you work out the details... some therories don't spin the vanes at all. and some spin them the wrong way.
i got my review for my job this week. it's only my second review ever. the first one was last year's review. apparently, i am a man of few words. and even fewer capital letters.
locking gauntlet: 8 gp. paladin's +3 holy demon bane cold iron silvered lance: 100,000+ gp. watching a pit fiend drop it into hell: priceless.
so i was preflighting my airplane the other day. another guy was nearby doing the same. a flight of four f-18s left moffet and circled overhead. we both stood there with our beaks pointed at the sky like penguins do. he said something inane like, pretty huh? i said, my wife won't let me have one.
some people noticed something unusual in this
post. no i don't have 20 toes. i could write up an explanation. but it would be way more intimate than i'm willing to be on a blog. ain't sayin' nuthin' more.
so i took my flat tire to the local tire shop. i was pretty sure i'd be buying a new tire given the size of the object that had violated it. but the nice man just said, i figgit. i said, you figgit? he said, yes yes i figgit. okay, figgit!. i left him to figgit. i came back later and sure enough. he figgit. ten bucks.
is a satellite image of our house. it's the orange roof in the middle. the image is a little old. the neighbors removed the holly trees. you can see some of the larger rose bushes. pretty neat huh?
one morning garrett wanted to play. he didn't want to go to the doctor's. he wasn't being bad. he was effectively avoiding everything he was supposed to do. by playing. nicely. he was playing in the car in his pj's when mom stepped into the garage with an armload of clothes. she pauses, gives him a look. somewhere the music from good the bad and the ugly starts to play. doo ee oo ee ah.
religion in school
bennett's homework one week was to learn about the major religions in the world. all of them. i thought it was strange at first. religion was taboo in my public high school. and i grew up pretty ignorant. now i think teaching no religion in public schools is a colossal error. the world would be a much better place if everyone had at least minimal exposure to religions other than the local dominator. replace exclusion with curiosity.
bennett lost one of his front teeth eating waffles on march 31st. and now boy does he look silly. the tooth fairy left him a wooden nickel. april fool's! hahahahahahahah!
the presidential fitness test is coming up later this month. a first grader has to run a quarter mile in 1:53. is it just me or does that sound ridiculously fast? anyway, bennett ran to the bleachers with me. it took a bit of encouragement (yelling). actually, he did great. but he got me back anyway once we were on the bleachers. he counted the laps: 1, 2, 3, 3, 3, ... 7, 8, 4, 5, ... and tossed in some encouragement (yelling). is that all the faster you can run? etc. he's quite the trash talker. just ask mom if you don't believe me. to echo joe, i swear i have no idea where he gets it.
hide and seek
my sister threw a birthday party for her youngest daughters. it was great fun. the older kids were off playing games and generally being good. nature called. on the way out of the only bathroom i noticed a kid hiding in the shower. moments later there were teenagers rolling on the floor laughing so hard their sides hurt.
casey & andy
is one of my favorite casey and andy web comic strips. i was reminded of it this weekend at david bruce winery. nature called and apparently i was sitting still for too long. the lights went out and i couldn't get them to come back on.
good joe blog
when you go for quantity, sometimes you come up with quality in your blog. example
referring to president bush.
i stayed up all night trying to get delta tao's web server back up and running. the next day i took a nap with the boys. there was a power outage while i was asleep. i woke up and looked at the blinking clock: 1:00. i thought i had jostled the power cord when i put the boy's book down to sleep and reset the clock. therefore i'd been sleeping for one hour. but really it was 5:40 and going on time for dinner. i had actually slept for a much needed 3 hours.
alisa swiftie 2
remember when some airlines would bring you a hot towel to wipe the skunge of travel off your face. i was reminiscing about my first experience with one and how i didn't know what to do with it. alisa swiftie called me an unwashed heathen.
i love my wife. sometimes she says the funniest things without realizing it. we call those alisa swifties. one night at the gaming table one of the players pulled an alisa swiftie and i had to explain. the gm says, make dc 16 reflex saves vs fireball. the rogue said i take no damage, evasion. the ranger chimes in with the alisa swiftie, you're cool. get it?
i like magic tricks. one of my favorite is bending a fork at the dinner table. one time i "bent" one of my grandmother's spoons. she was screaming at me to stop. it was awesome. then i swapped her undamaged spoon for my "bent" one and suddenly there were no bent spoons on the table. the second gotcha. good trick.
now that admin is on a bigger computer i copied my music collection to it and connected it to the stereo instead of my desktop computer. now we can listen to music without requiring my desktop computer be on. wee.
i drink way too much diet coke. it's a rather powerful diuretic. and i found out recently in terms of sperm motility it's way more effective than the old unprotected sex gold standard vinegar and water douche. i wonder if the two are related. maybe diet coke is incompatible with living organisms and kills bacteria in your gut causing mild diarrhea as easily as it kills sperm well you know where.
i love my boys. i don't want to wish time away. but if i did, here are some of the things i'd wish for: i want to be responsible for, washing one head of hair, cleaning two ears, brushing 28 teeth, clipping 10 fingernails, 20 toenails, wiping one nose, and one bottom.
i learned to sign the alphabet when i was a cub scout. it was just one of those things kids did. one year coaching wrestling there was this deaf kid. he could read lips pretty well but sometimes names were impossible for him. so i finger spelled them. if you've never experienced it, it's a pretty strange feeling to have blood flow into parts of your brain where 25 year old memories are stored.
i stopped buying textbooks in college when i noticed that i opened one for the first time and cracked the spine just before the final test.
bennett's a little messy when he brushes his teeth. he has bright blue toothpaste. so messes he's responsible for are pretty obvious. one day i discovered toothpaste under the sink counter lip. how(!) did he get toothpaste there. so i made him clean it up. he did. when i went back there were soap dribbles splattered all over the mirror. i think i failed to make my point. sigh. some year.
the old admin computer is now in pieces on the floor in the library. it collected dust for years. a /lot/ of dust. disassembling it made me wax nostalgic. apple was experimenting with designs that were easy to open and tinker with. this was an early and largely unsuccessful attempt. it has many little plastic latches and hinges. the whole thing unfolds like some sort of bizarre kid's puzzle box. the next generation was vastly superior. pull a trap door style latch and everything falls out. i remember joe opening a new one at macworld while an apple guy was giving a demo with it. i wonder if the computer recycling place would like me to re-assemble the puzzle box before dropping it off.
screen saver 1 : admin 0
it's 5 am. been up all night. finally get the new admin set up just the way i want it. yay! the boys wake me up at 7:45 am. boot the desktop computer and admin's missing. forgot to turn of the energy saver settings. admin went to sleep. pah. well at least one of us could. am i really done now? we'll see.