Tertiary Source

Ice tray stalagmite

2010-02-21 20:19:22
Look! I had a stalagmite in my ice cube tray.
an ice cube tray
what is that?
it sticks out against a card

Eleventy-one thousand eleventy-one

2009-08-14 09:08:00
Here's a million-to-one photo I took yesterday:
odo: 111111, 44 mph

Remember the significance of the three circles!

2009-07-10 14:57:28
When I was a freshman I took Philosophy 110. It was a big lecture, and the professor had a habit of rambling (which I mostly found entertaining); there was the customary falloff in attendance as the term went on. During one lecture the professor was working up to making three points and put some bullets on the whiteboard:
He then promptly distracted himself with a tangent about how boring people drive Fords, and whenever you see a Ford it's being driven by a boring person. After a couple minutes of this he turned back to the board and said, "I have no idea why I made these three circles. They must mean that boring people drive Fords." This got a chuckle out of the class, and he added, "Remember that! It'll be on the final."

Vaccine fears and risk tradeoffs

2008-12-26 11:28:25
This weekend's This American Life included interviews with some of the participants in this summer's measles outbreak. I learned about the outbreak from a somewhat overblown reaction from Phil Plait. From memories of Plait's older material, I expected a little lesson in conditional probability. Not finding one, I did an analysis of my own. I reached the surprising-to-me conclusion that, even with this summer's outbreak, the risk tradeoff between measles exposure and vaccine side effects is not totally unbalanced. My writeup at the time got lost in comment noise, so I'll condense it again here.

A duck from the Economist

2008-12-08 10:32:10

Here's a nice duck from the Economist. It's interesting that coups d'etat have become less common in recent years. It's also interesting that these commandos are reaching through the grid lines to pat the data.

Coups and attempted coups worldwide

Rail fuel economy

2008-12-05 01:04:24

Dylan Foley pointed out to me that my question about CSX's advertised fuel efficiency has previously gotten attention from FactCheck.org.

Musical Doppler self-sonar

2008-11-14 18:42:18

If you stand reasonably close to a road, the sounds of passing traffic get Doppler shifted: they start off high and end up low, "wheeeee-oooooom." Professional and amateur musicians have sophisticated training in recognizing frequency ratios. (Though, explicitly mentioning the relationship between frequency/wavelength ratios and intervals is more common when players of string instruments experiment with making harmonics.) How accurately could you estimate the speed of a passing vehicle by the sound it makes?

What's the antimatter content of a banana?

2008-10-21 11:06:37

Antimatter is strange, exotic stuff, right? Only produced in dangerous physics experiments? Leads to complete annihilation with ordinary matter?

Sort of. It's a question of quantity.

Recent questions


Older questions

How many Homo halibus ever lived? What fraction have been dug up and examined? What about other species? How does the fraction of individuals preserved and studied fall off as you moved back through time?
2009-05-29 Friday 07:11:19
Many people have jaws too small to contain thirty-two teeth, and have to have their "wisdom teeth" extracted. When did this practice become widespread? And how common is it to have an unusual number of teeth?
2009-02-24 Tuesday 12:41:14
A black hole at the end of its Hawking evaporation radiates with some very large power. But the high-power period doesn't last very long, since the mass is so small. Apparently the overall luminosity is small enough that it'd be hard to see a radiating black hole outside the solar system. What limit can you set on the density of very small black holes knowing only that, say, there are none in the room right now?
2009-02-04 Wednesday 22:19:29
How does the Stephan-Boltzmann constant σ "run" at temperatures where radiation modes other than photons become accessible?
2009-01-31 Saturday 13:34:02
A metric for cheap eating: calories per dollar?
2009-01-27 Tuesday 11:48:35
A jugful of water adds some thermal inertia and makes an empty refrigerator cool more efficiently. A tubful of water ought to do the same thing for drafty old house. How big is the effect?
2008-12-08 Monday 09:59:41
If you pull two connected blobs of Silly Putty apart slowly, the thread between then stretches plastically; if you pull them apart quickly, it fractures cleanly. What sets the threshold? How sharp is it?
2008-10-20 Monday 16:16:27
What's a typical pattern of presidential pardons? How has this changed under recent administrations?
2008-10-13 Monday 17:46:13
The Economist claims that some 1200 people have died crossing from Mexico to the US since 1990, compared to about 300 killed trying to cross the Berlin Wall during the 28 years it was up. Fatalities per mile? Fatalities per legal crossing? Estimates of successful crossings?
2008-10-11 Saturday 09:54:20
What's the pressure inside an unopened soda bottle (or can)? What's the rate at which CO2 comes out of solution at ambient pressure? How much does the bubbling change the temperature of the liquid?
2008-09-23 Tuesday 19:19:09