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:
o
o
o
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

[none]

Older questions

The representation of an integer in base b has some digits dn,⋯,d0. For example the number 42 = 4×101 + 2×100 has d1=4, d0=2 in base b=10. It's sometimes convenient to switch to a different base, frequently binary (b=2) or hexadecimal (b=16). Is there ever a reason to switch to noninteger b? What pathologies would such a representation have?
2009-04-20 Monday 14:39:54
Venoms have evolved independently in several different vertebrate lineages: in snakes and lizards, and in the platypus, and in one other mammal. What are the transitional stages for venom to appear? How would the appearance go in, say, a population of people?
2009-04-01 Wednesday 17:41:46
Computers have fast storage with limited space (RAM) and slower storage with fewer overall limits. How could this set of constraints change and make computing fundamentally different? How would similes about how "your brain is like a computer" change? Is there a better model for the brain?
2009-02-23 Monday 15:23:33
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
Much of the work of digestion is done by bacteria in the gut. Could an appropriately engineered infection permit someone to extract nutrition from normally indigestible materials, like grass and wood?
2009-01-29 Thursday 19:37:59
A metric for cheap eating: calories per dollar?
2009-01-27 Tuesday 11:48:35
Children's medicines come suspended in goopy liquids. Some part of the medicine always stays behind in the measuring spoon. Do dose estimates like "3/4 teaspoon twice daily" include a correction for the left-behind part of each dose? Do different types of dosing cups make a difference? Or do other factors introduce more uncertainty?
2008-12-29 Monday 19:14:27
How strong is the correlation between income tax witholding / refunding and tolerance for government spending?
2008-10-14 Tuesday 23:05:05
If you feed a Markov chain its own output, does its behavior get more stable or less stable?
2008-09-29 Monday 17:33:56