# Built on Facts

# Archives for **August, 2009**

There’s an interesting book I’m working on called The Fall of Rome: And the End of Civilization, by historian Brian Ward-Perkins. He argues (against a prominent modern school of thought) that Rome did indeed fall rather than merely change, and that European civilization really was wrecked pretty hard with a recovery that by many fairly…

Today I bought a sandwich at Subway. 12″ ham on “Italian herbs and cheese” bread, American cheese, lettuce, tomatoes, bell peppers, sweet onion sauce. After tax, the cost was $5.41. I handed a $10 bill to the young guy behind the register. By young I’m guessing 18ish. As such I was going to get $4.59…

And God said, Let there be light: and there was light. – Genesis 1:3 This post is going to need the standard math disclaimer. Though there’s math that looks horrible, you don’t actually have to know any math to follow the ideas. Give it a try! Over this week we’ve looked at the four Maxwell…

Fundamentally Maxwell’s equations describe the origins of electric and magnetic fields. Given a set of conditions on the right hand side of the equations, you’ll have fields described by the left hand side. Between the four equations the fields are uniquely specified, and there is nothing more to include. Thus far we’ve seen electric fields…

So far we’ve seen that electric charges create electric fields. We’ve also seen that magnetic charges would create magnetic fields if there were any such things, but there aren’t. If you’re in the business of creating electric fields, as the entire electric power industry is, one way of doing so is to pile up a…

In our examination of the first of Maxwell’s four equations, we saw that magnetic charge doesn’t exist as far as we can tell. On the other hand, electric charge permeates every aspect of our existence. The motion of charged electrons is one of the central pillars of modern civilization. The way that electric charge creates…

All this week we’re going to be briefly looking at James Clerk Maxwell’s greatest contribution to physics – his theory of electromagnetism. The consequences and applications of the theory fill many volumes, but the conceptual and mathematical foundations of the theory can be expressed as four short and relatively simple equations. These are Maxwell’s equations,…

All right ladies and gentlemen, take out your calculators. Punch in the number 4. Whack the square root button. What do you get? Unless I am badly mistaken, you’re going to get the number 2. As you probably remember, the square of a number is just that number multiplied by itself: 3 squared gives 9,…

The excellent readers of this blog have left numerous astute comments about the Nuke the Moon post, assessing the difficulty of knocking aside asteroids via nuclear explosions. The two most common themes are orbital mechanics and using the lunar mass itself in a sort of mass-driver configuration. Both are excellent points. The orbital mechanics are…

Graduate school is like the previous 16 years of school in that you learn things and take classes, at least for the first couple of years. On the other hand it’s also much more like a regular job than the previous schooling. You do work that’s unrelated to class, and you get paid. Maybe not…