mspringer | June 20, 2009It'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 run with absolute control centered on an Assembly of Experts headed by a Supreme Leader, the Ayatollah Khamenei. They're unelected and above any system of checks and balances. But on the other hand, they're not really a governing body as such either. The actual daily government is an elected…
mspringer | June 19, 2009I 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 math. Which kind of surprised me, I didn't realize I had been doing it. Maybe I do tend to be less rigorous when I'm not actively doing work. In either case it's about to come to an end, as in about a week I'll be back at school teaching and getting some research done. There will be math. (But it…
mspringer | June 18, 2009Tom 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 through the wire all at once. The following sequence of events then happens in a tiny fraction of a second: the current very rapidly generates a magnetic field, in accordance with Ampere's law. This rapidly increasing magnetic field generates an electric field, in accordance with Faraday's law.…
mspringer | June 17, 2009A 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 bacon into the Asteroid Belt.
A metaphor, like the decibel thing we discussed earlier? Maybe, maybe not. Let's work it out and see.
The first thing to notice is that there's several levels of complication involved depending on how much detail we want. Roughly speaking there's two sources of gravity…
mspringer | June 16, 2009I 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 insides have to hold themselves quite closely to the classical Fahrenheit value of 98.6, which is 37 Celsius. If my body were a perfectly insulated system with no way to generate heat internally, my body would warm the water up and the water would cool my body down until they reaches a equilibrium…
mspringer | June 15, 2009Over 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 effects of greenhouse gases.
There's no shortage of reasons it might not work. The most obvious is that climate is not fully understood as it is, and so massive alterations may have unintended consequences and make things worse. Especially if the methods of geoengineering result in permanent changes,…
mspringer | June 14, 2009Saw "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 have noticed that when you start to fill a balloon, its radius expands very rapidly at first before slowing dramatically. A water balloon will go from 1 to 2 inches much faster than it will go from 6 to 7 inches. Why? Because if you fill the balloon at a constant rate, you're increasing the…
mspringer | June 13, 2009There'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 Nerd Canon too. The names of the authors of its works are more like Asimov and Feynman. It's a list that's certainly not all science and science fiction, though those are much more strongly represented than in most general lists. To me knowledge no one has ever written such a list up, but it exists…
mspringer | June 12, 2009You 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 mathematicians.)
It's all in good fun, and it happens within disciplines as well. There's occasional good-natured sniping between experimental and theoretical physicists, and between the various sub-disciplines at different energy scales like particle physics and solid-state physics.
The story more…
mspringer | June 10, 2009There 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 wherein I joined the chorus of voices deriding the ludicrously horrible track record of predicting the impact of the stimulus. Well, another month another data point, overlaid on the otherwise unmodified Obama stimulus prediction:
Not only is it much worse than what the stimulus was supposed to…
mspringer | June 9, 2009Ethan at Starts With a Bang busts two Galileo myths.
1) That Galileo actually dropped weights off the Leaning Tower of Pisa. He almost certainly didn't. Like the story of George Washington and the cherry tree, it's an instructive parable not at variance with the character of the man - but not an event that actually happened.
2) That the experiment would have worked even if Galileo had done it. It wouldn't have. Air resistance would mean that otherwise identical objects of the same mass wouldn't have hit the ground at the same time.
Those are the two points that Ethan makes. They're both…
mspringer | June 8, 2009Just 24 light-hours away it's still Sunday, right? Oh well. On to the math!
If you ask a mathematician to define a circle, you'll probably hear something along the lines of "A circle is the set of points in a plane equidistant from a given center point. The name of the distance from the center is the radius." A mathematician will state it more precisely, but that's the gist. As a technical matter - and mathematicians love technical matters - this is actually somewhat different from what kids learn about circles in school. Kids would probably say a frisbee is a circle, but really it's…
mspringer | June 6, 2009Our landings have failed and I have withdrawn the troops. My decision to attack at this time and place was based on the best information available. The troops, the air and the Navy did all that bravery could do. If any blame or fault attaches to the attempt it is mine alone.
- Gen. Dwight Eisenhower, undelivered statement in the event of the failure of Operation Overlord
On this day sixty-five years ago the armed forces of the United States, the United Kingdom, Canada, free France, Poland, and Norway invaded Nazi-held territory at the beaches of Normandy. Despite the unfathomable preparation…
mspringer | June 5, 2009I don't know if you've been reading Photo Synthesis, but if you haven't you're missing a real treat. Currently there's some incredible photography and video of amateur rocketry at fairly large scales. Amazing stuff. A hundred years ago the idea that an amateur of comparatively middle-class means (well, after a lot of saving anyway) could send rockets to the edge of space would have been laughable.
But we've got a long way to go as well. Not long ago Gene Expression commented on a Seed Magazine piece on planetary astronomy (do you subscribe?) and noted that the problem of interstellar…
mspringer | June 4, 2009Reader Abby Normal(!) writes in with an excellent question:
Something in your post about Physics in Star Trek, May 18, 2009, has been bouncing around my brain. You stated that a black hole has the same mass, and therefore gravitational pull, as it's parent body. That makes perfect sense. But as I understand it a typical black hole is formed by a collapsing star. (Ignoring supermassive black holes, which I know form differently.) So why then does a star emit light prior to it's collapse but afterward, assuming it becomes a black hole, can light no longer escape? Does it have to do with the…
mspringer | June 3, 2009There's many, many sports out in the world that involve sharply hitting a ball with something. Baseball, tennis, golf, cricket, polo, you name it. After being hit, a ball describes a trajectory determined by the gravity of the earth and the interaction of the ball with the atmosphere. This can be exploited in many sports, since different trajectories can be useful in different situations. Golf and baseball especially are built on tweaking air flow around the ball in order to make it do precisely what the athlete wants. Tennis too, which has been drawing a lot of interest with the…
mspringer | June 2, 2009All right ladies and gentlemen, today we're performing an experiment! More of a demonstration, really, but one that's very easy and will impress your friends. You will need:
1) One remote control.
2) One camera phone.
The vast majority of remote controls operate via an infrared light-emitting diode situated at the front of the device. You press a button, and the diode lights up in a particular pattern of pulses corresponding to the button you pressed. A little sensor at the front of the TV detects these pulses and converts them into the electric signals that tell the TV to switch from…
mspringer | June 1, 2009This is the conclusion of the Ritz variation discussion we've been doing. Tomorrow we'll get back to less arcane and more entertaining physics, I promise! We're capping things off today by demonstrating the actual technique in detail for an example where we already know the answer. What we're doing is finding the ground state of the 1-d square well.
Before we even start, we can look up the actual answer and use it to give us an idea of how accurate our Ritz approximation ends up being. The ground state energy of a particle in a 1-d box is:
Now that we know what the answer is, we can go…
mspringer | May 31, 2009Nobody ever asks the interesting questions at presidential press conferences. But if somehow I could choose a question, it would be this:
"Mr. President, has the NSA solved the integer factorization problem?"
Of course it's unlikely he'd know off the top of his head, and even if he did he certainly wouldn't give me an answer. That's the kind of codebreaking knowledge that quickly becomes useless if everyone knows you know. Large chunks of modern cryptography are based on the fact that it's easy to multiply numbers like 17863 * 8161 = 145779943. But given a number like 223233911, it's a…
mspringer | May 30, 2009There's a lot of important things going on in the world. Kim Jong Il is exploding nukes and launching missiles over Japan. A Supreme Court justice has been nominated. The treasury bond market experienced its steepest yield curve ever.
Whatever. Today we talk about Jon & Kate Plus 8.
Jon and Kate, should you have happened to miss all the Sturm und Drang, had twins before they were famous. They wanted one more and were biologically predisposed to difficulty, so they used fertility treatments and ended up with sextuplets. Correctly sensing an interesting drama, TLC offered them a show…