Built on Facts

“I returned day before yesterday,” he answered, while he leaned his arm on the keys, bringing forth a crash of discordant sound.
“Day before yesterday!” she repeated, aloud; and went on thinking to herself, “day before yesterday,” in a sort of an uncomprehending way. She had pictured him seeking her at the very first [...]

[Read more →]

A few days ago I saw the movie Rudy for the first time.  It’s a story of a young guy in the 70s who wanted to play for the Notre Dame football team.  He was a small guy, and after tremendous adversity finally managed to get on the practice team to function essentially as a [...]

[Read more →]

Famously there are these exercises called Fermi problems, which are basically questions designed to be solved only by reference to approximation and dimensional analysis.  They aren’t even necessarily physics problems - the canonical example is “How many piano tuners are there in Chicago?”.  The reason why they’re interesting to try to solve is because it [...]

[Read more →]

Earlier I was killing a little time today by reading about MOND. It’s an ad hoc attempt at a solution so the galaxy rotation problem. Essentially the outer portions of galaxies rotate a lot faster than they should given the their visible mass distribution. The obvious solution is that there’s mass which [...]

[Read more →]

Vis consili expers mole ruit sua.
- Quintus Horatius Flaccus
The words of Horace above attain a spare and austere beauty in Latin, but the meaning is carried equally well in English. Force without wisdom falls of its own weight. Two different sets of words carry his millenia-old thoughts to the present time. There [...]

[Read more →]

There’s a video circulating on the internet that purports to show popcorn being popped by the radio waves emitted from cell phones. It’s been extensively debunked by multiple sources, including Snopes and Wired. Swans on Tea has a quantitative analysis which I highly recommend. Snopes even gives good reasons why it’s probably [...]

[Read more →]

When I was a young child, my uncle Fred used to try to convince me of some pretty outlandish things. His favorites were to say that the earth was flat and that England was a hoax. I was old enough to know better and I tried to argue as best I could, though [...]

[Read more →]

Weddings all around for my family this week. I’m in my hometown with some time to kill this summer before my TA duties resume in July, which gives me the opportunity to catch up with old friends - one of whom was married this weekend. My parents went to a different wedding of [...]

[Read more →]

In a vacuum, the speed of light is a universal constant: 299,792,458 m/s exactly. For light traveling through a substance like water or glass the speed is lower. The light hasn’t actually slowed down. Instead, the interaction with each successive atom in the material takes a little bit of time and so [...]

[Read more →]

So you’re sitting in your car at a red light. It turns green and you stomp on the gas. 0 to 60 in what, 9 seconds for an average car? Probably so. But that acceleration doesn’t stay constant forever. Air resistance and engine inefficiency eventually brings you to a maximum [...]

[Read more →]