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
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
With continuous thrust, it takes less energy to eject an object from the solar system than to crash it into the sun. This isn't the case for satellites in low-earth orbit, since they skim the atmosphere already. For geosynchronous satellites? Where is the boundary?
2009-02-13 Friday 08:41:34
A metric for cheap eating: calories per dollar?
2009-01-27 Tuesday 11:48:35
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
Gerrymandered Congressional districts tend to protect extremists at the expense of moderates. Will the House be more or less polarized after the turnover in yesterday's elections?
2008-11-05 Wednesday 12:39:29
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
Political polls of a thousand people's opinions are reported with an uncertainty of 3%, which is roughly 1/√1000. Is this mostly Poisson counting? An election is just a larger statistical sample with a different set of biases. What is the margin of error on an election?
2008-09-20 Saturday 21:38:27
NPR has reported twice in the past couple weeks that NASA managers have expressed anxiety about the upcoming mission to service the Hubble telescope. Because the Hubble orbits further above the atmosphere than the ISS, where most shuttle missions have gone recently, the chance of the shuttle colliding with some space junk is "double" that on recent missions. Doubled from what? to what?
2008-09-20 Saturday 08:28:36