July 16, 2009
Yesterday I taught the basics of geometric optics to my Physics 202 students. We did plane mirrors, spherical mirrors, and thin lenses. All told it's a fairly straightforward chapter that's all theme and variations on one equation. The sign rules for object and image distances have to be…
July 15, 2009
Or: Deconstructing Dumbledore.
(Major and serious spoilers for Half-Blood Prince and Deathly Hallows follow. In fact if you haven't read them this will make very little sense.)
There's a lot of villains in the Harry Potter series. They are young and old, male and female, human and otherwise,…
July 14, 2009
A few days ago we briefly mentioned the chemtrail conspiracy theory in the context of water vapor in the atmosphere. Chemtrails are one of those conspiracy theories where belief is pretty much diagnostic of actual your-brain-is-defective crazy. Belief that NASA faked the moon landings is sadly…
July 12, 2009
Last week we did the sinc function. Let's do it again!
The function, to refresh our collective memory, is this:
Now I was thinking about jumping right into some contour integration, but on actually doing it again I see that it's a little hardcore for one post so eventually when we do it we'll…
July 11, 2009
To me this is interesting. To people like my parents, whose retirement depends significantly on their investments during their maximum earning years (ie, now), "interesting" might not be the word they'd pick. Here's a graph I pulled off of Vanguard, representing a $10,000 investment exactly 10…
July 10, 2009
From the front door of the physics building to my apartment is about two miles. That's not all that far, so lately I've taken to just walking instead of riding the bus. In theory it's a relaxing time to think and look at the interesting things that you miss from a vehicle, aside from being…
July 8, 2009
There's a continuum of crazy in the world of conspiracy theories. On one end are the at least somewhat plausible ideas like that Oswald didn't act alone in the JFK assassination. On the other end are the downright schizophrenically crazed theories, say that the world is actually run by evil…
July 7, 2009
Today was my first day teaching recitation for the summer session Physics 202, the algebra-based second half of intro physics. Physics 202 focuses mostly on electricity and magnetism, where the first course (Physics 201) was mostly classical mechanics.
The summer semester is split into halves for…
July 6, 2009
You're all familiar with Dr. Isis, also of ScienceBlogs? She likes cute things. She likes science. Despite the fact that I'm a so-square-I'm-practically-cubic reactionary, I like both of those things too. But when physicists try to make their physics cute it's a cringe-worthy disaster waiting…
July 5, 2009
I first met this function sometime in the year 2001 in the manual for a graphing calculator. The manual said that the function had no "closed-form analytic antiderivative" but nonetheless the calculator could integrate it numerically. At the time I had no idea what any of that meant, but upon…
July 4, 2009
Today you should grill some good food, shoot some fireworks, spend time with your family and friends, and take a few minutes to remember awesome magnitude of what our forefathers did on that July in 1776:
We hold these truths to be self-evident, that all men are created equal, that they are endowed…
July 3, 2009
Last night I saw a classic conservation of momentum problem in person. It was about midnight, and I was on a service road beside west Houston's Beltway 8 (avoiding the tolls) when I slowed down to stop at a red light. In my rear view mirror I saw the red and blue flash of emergency lights…
June 29, 2009
The National Weather Service does a very useful thing for people who live in an area expexted to experience severe weather danger. I have a little Firefox app in my browser that links to the NWS and advises me of the current conditions and forecast for the next few days, and as part of its…
June 28, 2009
I've been away from campus visiting family during the first part of the summer, in one of those rare confluences of events where research, classes, and teaching all find themselves on temporary hiatus. While it's pretty rare, I'm glad to take it. It is giving me Mathematica withdrawals though,…
June 27, 2009
There's a lot not to like about the Waxman-Markey cap-and-trade bill that passed the House this last week. You'd expect the right not to like it, but this bill has many people of all political opinions unhappy.
From the left: The bill is a huge 1300ish page monstrosity developed behind closed…
June 26, 2009
Alas for Michael Jackson. Talented musician, deeply broken human being. Most of my knowledge of him was through cultural osmosis rather than his actual music, and I'm young enough so that I can't really remember the time before he was a punchline about changing skin color, disastrous plastic…
June 24, 2009
Chad Orzel's got a great post up about the physics of Lord of the Rings. It's about Legolas the elf and his excellent eyesight. His eyes are so good that in fact they're probably operating well beyond the physical diffraction limits of any optical device with a human-sized pupil. Some…
June 23, 2009
Yesterday we dumped a bucket of electrons on the Statue of Liberty and watched what happened. The most important thing we saw is that all the charge immediately distributes itself over the outside surface of the statue in such a way so that the electric field within the statue is zero. We also…
June 22, 2009
Today we need an example of something weirdly-shaped and electrically conductive. There's no shortage of such things, so we might as well go with the iconic. This is the Statue of Liberty:
It's made out of copper, which over the years has taken on a decidedly not-copper color due to chemical…
June 21, 2009
If you want to kill some time, try to think of all the different definitions of the word "set". You have chess sets, sets in tennis, sets of dishes, sets musicians play, sets as abstract mathematical entities, television sets. You can set a table, set a clock, set someone straight, set a price,…
June 20, 2009
It's Saturday, and it's' sort of tradition to set the topic to something not necessarily connected to science. At this point I think there's not a whole lot in the world that's of more immediate interest than what's going on in Iran.
The summary, which you already know: Iran is a theocratic state…
June 19, 2009
I have a friend who is also in the science business on the outreach/educational side of things. Last night he and some other friends and I were out on the town (is that what the kids call it these days?), and he mentioned that he liked this site as it's been while I'm on break from school. Less…
June 18, 2009
Tom at Swans on Tea (You do read Swans on Tea, right? You're missing out if you don't.) points out one of the more impressive physics demos out there. It's quarter shrinking, in slow motion.
You take a $0.25 coin, stick it in the middle of a coil of wire, and dump an tremendous amount of current…
June 17, 2009
A reader in the thread on Snow Crash came up with an interesting exercise. In the book, Hiro Protagonist has a pretty awesome car. He'd better - he uses it for time-critical deliveries for the Mafia.
The Deliverator's car has enough potential energy packed into its batteries to fire a pound of…
June 16, 2009
I was doing some swimming today, and when I got out of the pool and dried off the first thing I did was to get some ice water to cool down a bit. Good stuff, there's not much that's as satisfying as cold water to a thirsty person on a hot day.
Ice water is at or about 0 degrees Celsius, and my…
June 15, 2009
Over at The Volokh Conspiracy, Jonathan Adler notes that the NAS is starting to look into the possibility of geoengineering to roll back human changes in the climate. For those of you who haven't heard, geoengineering is the process of deliberately changing the climate to compensate for the…
June 14, 2009
Saw "Up" yesterday. How Pixar manages to be so consistent in their astonishing quality is entirely beyond me. In a bit of a tribute, this Sunday Function is not about any dramatically important special function, but instead it's about filling a balloon. Air or water, as your preference.
You'll…
June 13, 2009
There's a list of books a cultured person is supposed to have read. Its size and composition vary depending on who you ask, but roughly speaking there exists a Western canon containing works by authors with names like Shakespeare and Dostoevsky and Milton and Sophocles. There's something of a…
June 12, 2009
You might remember an older xkcd comic ranking various sceinces in terms of their purity. Psychology is just applied biology, biology is just applied, chemistry, chemistry is just applied physics... etc. Math is at the top. (Philosophers would like to think they're the top level, one rank above…
June 10, 2009
There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.
-Richard Feynman
Not so long ago I wrote a snarky post about economics…
