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

Sensitivity to market fluctuations: a disadvantage to overly progressive taxes?
2009-02-25 Wednesday 20:31:21
There's a theorem in control theory that sets limits on how quickly the gain of a feedback system can change with frequency without driving oscillations. This is the logic behind using the integral and/or the derivative of the feedback signal in mechanized control systems. One factor in the current financial disaster is tension between short-term and long-term risk, a problem that also appears in smaller-scale "markets." Suppose this tension were reduced by, say, paying fund managers with investments less liquid than cash, in some quantifiable way. Are cash commissions guaranteed to have boom and bust oscillations? Do oscillation-free commission schemes exist?
2008-12-31 Wednesday 10:03:07
A stopped clock is exactly right twice a day. With some error-weighted averages, a stopped clock is more accurate on average than a clock running, say, ten minutes fast. What averages do and don't have this property?
2008-11-19 Wednesday 23:40:45
New "open" signs at restaurants, with bright red and blue LEDs, bring out some chromatic aberration in my glasses: viewed peripherally, the different-colored parts don't line up. Quantify? Why have I only just started to notice this?
2008-11-11 Tuesday 09:44:38
Passing traffic makes Doppler-shifted noises ("wheeee-oooom"). Useful trick: map between musical interval of the shift and the speed of the traffic? (maybe)
2008-11-11 Tuesday 09:38:19
Suppose I replace an incandescent light bulb with a more expensive, more energy-efficient, longer-lived light — a CFL, an LED, whatever — based on the expectation that it'll cost less over its life. How old does my incandescent bulb have to be before I actually save anything?
2008-10-28 Tuesday 21:42:08
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
How strong is the correlation between income tax witholding / refunding and tolerance for government spending?
2008-10-14 Tuesday 23:05:05
If Hawking's connection between black holes and thermodynamics is right, astrophysical black holes --- for which general relativity predicts everything bizarre happens well inside the horizon, and for which there are observational evidence --- are at the zero-temperature limit. What's the "warmest" black hole for which there is observational evidence? What's the transition "temperature" where quantum gravity starts to matter?
2008-10-06 Monday 19:45:48
An observation by Consumer Reports, that breakfast cereals marketed to children aren't terribly nutritious, has gotten some evening-news press. The main contribution of the Consumer Reports release seems to be that they bought a bunch of cereal and read the nutrition labels. What's new here? Has the composition of existing products been tweaked? Have some sweeter brands been introduced to replace healthier ones? How do these sorts of news blobs correlate with sales, or with marketing spending?
2008-10-06 Monday 12:29:26