October 29, 2008
#4 - Michael Faraday
One day sir, you may tax it.
- Michael Faraday, asked by the British Minister of Finance about the practical value of electricity
With Michael Faraday we begin to reach the most rarified heights of physics achievement. Faraday worked largely in the first half of the 19th…
October 28, 2008
In the United States, there are about 4 million 8-year-old children. To the extent that statistical averages hold true, around 640 of them will die this year. The largest single cause is motor vehicle accidents, killing a quarter. Cancer will kill another sixth, heart disease around fifteen…
October 28, 2008
Let's say we want to know how big the earth would be if it were compressed down so far that it became a black hole. We don't really know much about black holes, but we do know something about escape velocity. Stand on the surface of the earth (which had radius r) and fire a projectile upward, and…
October 27, 2008
Hey, sorry for having no Sunday Function yesterday. Life and travel conspired in such a way as to prevent it. Well, there's always next week! But hey, at we have a post for today.
In physics, as in all mathematical disciplines, we have a lot of need for equations. Those equations contain…
October 25, 2008
This weekend finds me on the road again, and driving a few hundred miles across rural Texas and Louisiana puts one in the mind to contemplate the expanse above. You're only about an hour's drive from space right now, if you can find a car that will go straight up. But for now we have to settle…
October 24, 2008
A space shuttle launch is pretty expensive. Exactly how expensive depends on who you ask, but if you divide the yearly cost of the program by the number of launches you get something in the neighborhood of half a billion dollars. That's actually pretty trivial by federal budget standards, but it'…
October 23, 2008
#5 - Richard Feynman
I'm probably going to take some flack for this one. Feynman was and is so popular as a scientific writer, raconteur, and honest-to-goodness celebrity that his staggering scientific accomplishments are sometimes lost in the shadow of his own popular legend. But if we want to…
October 22, 2008
You know what irritates me? NCIS. Not the Navy's law enforcement agency, the TV show about that organization. I'm generally a fan of Law and Order style police procedurals, but that one just rubs me the wrong way. Why? The fetishize law breaking. Not the law breaking of the criminals they…
October 21, 2008
From the always good Ph.D. comics, we have this comic, which I saw pointed out at Pure Pedantry.
I'll defend this, a little. Football coaches are in large part responsible for the success or failure of a football team. In the grand scheme of things the position of a pigskin on a field is not…
October 21, 2008
Last Saturday I penned a snarky comment about the philosophy of science, and within a week I read something that's particularly interesting from that very perspective. Well, might as well use it when it has its uses. Some preliminary:
It is certainly either true or false that Julius Caesar's…
October 20, 2008
There's famously dozens of ways to measure the height of a building with a barometer. If you're sufficiently clever, you can think of many, many more ways to measure temperature with just about anything.
One of the most visually impressive ways to measure temperature is the Galilean thermometer,…
October 19, 2008
Time for a vacation! Grab a globe of the earth and pick a random number between 0 and 180 degrees for your latitude and between 0 and 360 for your longitude and set off on your vacation. It's exciting! You're bound for anywhere on earth, and every obscure location has the same probability of…
October 18, 2008
The standard Saturday random observations:
Via Adventures in Ethics and Science, a quote from Revere of Effect Measure:
A wag once commented (and I have quoted here often) that to expect a scientist to understand the philosophy of science is like expecting a fish to understand hydrodynamics.
I…
October 17, 2008
Let's say you have a thousand of your friends in a large field, and every one of them has exactly two coins - one penny and one dime - in his pocket. Or her pocket, as the case may be. No exceptions, they all have those and only those two coins. Now imagine nearly the same situation with a…
October 16, 2008
I follow cheerfully; and, did I not,
Wicked and wretched, I must follow still
Whoever yields properly to Fate, is deemed
Wise among men, and knows the laws of heaven.
- Euripides
Wise advice as quoted in the Enchiridion of Epictetus. With that in mind, let those of us to the right of center…
October 15, 2008
This week I'm teaching rotational motion to my students. Here's an easy problem from their textbook, which comes from the idea of using a flywheel to store energy. I'm modifying it from problem 9.41 in Young and Geller:
Suppose we want to built a flywheel in the shape of a solid cylinder or…
October 14, 2008
Mark C. Chu-Carroll at Good Math, Bad Math has an excellent post in which he mercilessly dispatches the misbegotten idea that infinity is a number. It's not.
How do we know? He explains it very well, but the fundamental thing to remember is that number is a word, and like all words it has a…
October 13, 2008
The Feynman Lectures are the bible of physics.
Because it's the definitive and authoritative sacred text? Nope. Because everyone has it but not many people have actually read it. This is too bad. The lectures are a fantastic way to learn about physics.
Richard Feynman was a brilliant…
October 12, 2008
Quick! Add up all the numbers between 1 and one trillion, inclusive!
The story goes that the great Carl Friedrich Gauss in his days as a little kid in late-18th-century German primary school was told with the rest of his class to add up the numbers from one to one hundred. The teacher was…
October 11, 2008
This post is skimpy, that is. No scantily-clad women, though I bet it would drive up traffic!
The post is skimpy because yesterday I spend several hours grading exams and six more driving to Louisiana. No time to write a good post and do the usual Saturday random observations and links. But…
October 10, 2008
I see that bailout is working wonderfully. Of course if it hadn't passed and the stock market had behaved identically, we be hearing that we were fools not to pass the bailout. And they would be wrong. Yes, I know God Emperor Paulson hasn't actually used any of his trillion dollar blank check…
October 9, 2008
#6 - Ernest Rutherford
The New Zealand physicist Ernest Rutherford was an incubator of genius, and a genius himself. His position on this list is probably a little unorthodox as he wasn't a very flashy scientist and he wasn't a theoretical wizard. He just happened to be a surpassingly great…
October 8, 2008
Physicists like to name things after their discoverers. Sometimes if there's a unit of measurement that doesn't have someone's name attached to it, they'll grab the name of somebody who worked in that field and use it. Let's take a look at some units, first a few examples not named after people:…
October 7, 2008
How'd the test go? Eh, ok I think. In particular I vapor-locked on a pretty easy question involving transforming E & B fields to another reference frame. There was another question where you had to prove that the energy-momentum tensor was Lorentz invariant, and I didn't get that one either…
October 6, 2008
Today is Judgment Day number 1 of 3. "Why today, and why are there three of them?" you ask.
Well ok, I exaggerated. It's just the first of three exams in my electromagnetic theory class. Let's see what's on the test... "special relativity, Lorentz covariance of Maxwell's equations, scalar and…
October 5, 2008
As we get closer to Halloween, let's take a look at one of the few functions that might cause a stir in Salem. I give you the Witch of Agnesi, for several values of its free parameter a:
The Witch is a geometric construction involving triangles that's easier to show than describe:
(Both images…
October 4, 2008
This is of course from the 1939 World's Fair. It represents the era of perhaps the most optimistic vision of science held by the public, from back when Progress was spelled with a P. The war put things on hold for a few years, and then we had a decade or so of glorious Streamline Moderne before…
October 3, 2008
Thursdays I'm not a fan of, because I teach two classes back to back. Since both classes are associated with a lab, that's six continuous hours in front of a chalkboard. Teaching I like, but six hours without a stopping leaves me pretty beat.
That's probably why in high school and below the…
October 2, 2008
A quick aside: via professor Bernstein at Volokh Conspiracy comes this delightful quote, regarding the reason for the specific $700,000,000,000 figure in the bailout bill:
"It's not based on any particular data point," a Treasury spokeswoman told Forbes.com Tuesday. "We just wanted to choose a…
October 1, 2008
We talk about the earth rotating on its axis. We say the same thing about tops, and spinning basketballs, and gyroscopes, and car tires, and pretty much everything else that spins. Rotations happen around an axis.
Well, except that they actually don't.
No, I'm serious. Rotations happen in a…
