2/13/12  As the World Turns

      How many degrees does the earth rotate in a day? How many times does the earth rotate on its axis in one year? We might be tempted to say the earth rotates a full 360 degrees per day, and rotates 365 ¼ times a year. If we did, we'd be wrong.

      Let's look at a simpler example of a rotating planet which orbits a star in four days. The same side of the planet will face the star four times per orbit. In one day the planet will travel one quarter of the way around, or 90° of orbit. If the planet travels a quarter of the orbit and rotates once around its axis, the side facing the star at point A will be facing 90 degrees away from the star at point B. (Top)

      To get the same side facing the star it must rotate an additional 90° to make up for the 90° of orbit. So in one day the planet rotates 450°. (Bottom) Which means the planet will rotate 5 times in one orbit around the star to make four days in a year.

      The same thing applies to the earth orbiting the sun. One day requires almost one extra degree, about 360.985° of rotation. In one year the earth needs one extra rotation to make up for the turn in the orbit, meaning it rotates 366 ¼ times on its axis per year.

      A 360.985° rotation to get the same side of the earth facing the sun is called a solar day. A 360° rotation is called a sidereal day. Does this make any difference? It does if you're into astronomy. It means to examine outer space you need to look in different directions depending on the time of year.

      For instance, to look at distant galaxy C at noon at point A the planet would have to look over its right shoulder, so to speak. At point B the planet would have to look over its left shoulder. But if you or the planet didn't care to look at galaxy C, I guess it doesn't much matter. Which is why this is filed under trivia.

1/18/12  Kill or Bee Killed

      Starting about five years ago stories circulated of an alarming development, bee hives were suddenly dying out. The phenonmenon was called Colony Collapse Disorder (CCD). All sorts of reasons were suggested why it was happening. The usual suspects were rounded up; pesticides, polution, genetically modified crops. We were killing off the bees. Disaster loomed.

      And now, the rest of the bee story perhaps you haven't heard. CCD is natural, nothing new, and bees are not going to disappear any time soon.

      Lawrence Harder from the department of biology at the University of Calgary and Marcelo Aizen from Buenos Aires set the record straight: There has been no worldwide collapse in honey bee populations; The bee disaster scenario relies on data which is too regional and doesn't represent global trends; Managed hives have increased by 45 percent over the last five years.

      So, the die-offs are isolated and not widespread. Bees as species are not in danger. Still, what's killing bees in those cases? Turns out the culprit is mother nature and not man; namely parasites, fungi and pathogens.

      Bees are subject to parasitic Varroa mites and tracheal mites. Pathogens include the Israeli acute paralysis virus and two other viruses that transform the shape of wings or cause a disease only affecting queen bee larvae.

      A phorid fly, Apocephalus borealis, parasitizes bees causing them to become disoriented and abandon their hives; a primary symptom of CCD. This fly lays eggs into the bee's abdomen. As the larvae grow the host bees begin to exhibit zombie-like behavior by walking around in circles with no apparent sense of direction. Bees then leave the hive at night flying blindly toward light. It eventually dies and the fly larvae emerge.

      The bottom line, parasites are the major component in CCD with fungi and disease playing a major role. Bees have been plagued by these for a very long time. Considering their ubiquity in nature, parasites, fungi and pathogens should have been the first usual suspects.

12/29/11  Brrrp... brrrrrp.... brrp... brrrp...

      There are two controls on a gas-powered lawn mower that mean "strangle". One strangles fuel, the other strangles air. These are the throttle and the choke. Appropriately enough, the choke is in the throat of the carburetor.

      The throttle and choke work as their names suggest, they constrict the passage of fuel or air. Think of the terminology we use. When we want more gas we "open the throttle." We strangle it less. You might say full throttle is when there's the least throttling going on.

      Rotary engines on early airplanes had a two-speed throttle. It was either on or off, there was no other speed. To slow the plane the pilot would cycle the engine on and off. That's why some WWI airplanes coming in to land sound like, "Brrrp... brrrrrp.... brrp... brrrp..."

      Planes don't have rotary engines now-a-days. Though they may have radial engines which look similar. Both have cylinders arranged in a circle around a central crankcase. While they look alike, there's a big difference. A radial engine is bolted in place and the crankshaft spins the propeller as you would expect. (red plane) On a rotary engine the crankshaft is fixed to the frame, the propeller is fixed to the engine and the entire engine spins. (green plane)

      The spinning engine made for some rather peculiar handling characteristics. A rotary engine was like a big gyroscope on the front of the plane. If you know about gyroscopes you know about precession. Meaning, when you pitch the plane you get a force to yaw the plane. In other words, when you dove the plane would turn at the same time.

      Pilots had to compensate for the gyroscope action when flying a rotary engine plane. In effect, the controls worked differently on a rotary engine plane than on other planes and so flying them was tricky. Not only that, with some maneuvers the spinning engine would sometimes rip itself out of the plane. Which might partly explain why more WWI pilots died in accidents than in aerial combat.

12/8/11  The Incredible Shrinking Man

      This is purely in the realm of fantasy, but what would it mean if a person shrunk down to an inch tall? In the movie "The Incredible Shrinking Man" we get an idea, only the wrong idea.

      In the film the tiny man wants to get down from a table so he rigs a rope, which is string, and climbs down. Thing is, he could have simply jumped down with no problem. Even though he's really small, the table is still only 30 inches from the floor. The acceleration over a particular distance will be the same regardless of the man's size. If a full-size man can safely jump down from a table, so can a tiny man.

      In fact, a tiny man would be able to jump down more safely than a full-size man. The tiny man has a great deal less mass and so the impact at the same speed will be less. The tiny man is so light and lands with so little force he might be able to jump off the roof safely.

      Here's a personal anecdote to back this up. One day sitting on my back stoop I saw a squirrel fall out of a tree from maybe 20 feet up. It landed with a thump, got up, and ran away back up the tree. A squirrel is so light it doesn't hit with as much impact as a man would falling 20 feet out of a tree. It also helps the squirrel has a higher strength to weight ratio, which is explained next.

      Perhaps you've heard about how incredibly strong an ant is because it can lift 10 times its own weight. That is not so incredible, its a matter of its being small. Muscles grow heavier with size at a higher rate than they grow stronger with size. Meaning the bigger and stronger an animal gets the less it can lift relative to its weight.

      The reverse is also true, the smaller it gets the more it can lift relative to its weight. The ant is not incredibly strong, its incredibly small and thus its strength to weight ratio is high. As it would be for any tiny creature, including a tiny man. A full-size man might weigh 200 pounds and it would be an effort to lift his own weight above his head. The tiny man might weigh a pound, but would have little problem lifting twice his weight above his head. Even so, he's only lifting two pounds.

      The tiny man would also move like a hectic little mouse with very quick steps. When a full-size man takes a step his foot will move about two feet. It takes time to move his foot that distance at a given acceleration. On the other hand the tiny man's step is maybe a half inch. It would take very little time to move his foot that distance at the same acceleration. It's like a long and short pendulum. In one second the long pendulum makes one stroke, the short pendulum two strokes. Yet they both cover the same distance.

      The tiny man could jump up higher relative to his height as well. A house cat can jump several times its height, maybe five or six feet high. A lion would have to jump 15 to 20 feet up to do the same. It can't. It's too big and the distance is too far. It's akin to the pendulums, a matter of acceleration of mass over distance. Distance is not relative, 20 feet is 20 feet no matter how big or small you are.

      The tiny man's voice and hearing would change, too. But I wouldn't worry about that. I wouldn't worry about any of this because it's pretty unlikely to ever happen.

11/21/11  Hell’s Other Kitchen

      Eating is a pure, primal pleasure. A pleasure we experience several times a day, every day, for our entire lives. We do it so often we don't always appreciate just how pleasurable it is. Sometimes it might be the only really enjoyable thing we do all day.

      Of course eating is important. You have to do it to stay alive. Good thing we like to do it. Besides needing food to stay alive, how important to mental health is having tasty food, food we enjoy eating? Turns out, pretty important. When eating becomes a chore, something you must do rather than something you enjoy doing... well, it's not unheard of for sick people to wither away and die because they've lost their appetite.

      Which brings us to science fiction stories. You know, ones where people eat cubes of processed food and meals in a pill. Where's the pleasure in that? Would that drive you crazy? Or if not actually batty, would such a diet be depressing? Would it put you off food?

      Now we finally come to the fun fact and trivia part.

      Having a supply of tasty food is one of the hurdles we face when contemplating long space flights. Even frozen food doesn't last indefinitely. It turns to unappetizing mush. NASA has discovered a constant diet of such mush is depressing. A depressed crew... Houston, we have a problem. Space flight is not all rocket science. Sometimes all the little details you never thought of can be a bigger problem than you ever imagined.