Do gun laws save lives?

Somebody pointed me at this interesting data the other day. The chart above (click to zoom) combines the “Gun Law Score Card” from the Law Center to Prevent Gun Violence in the US with homicide rate data from Wikipedia and voting results from the last US election. Do gun laws reduce the chance of being murdered?

Obviously, “Blue” states tend to have stricter gun laws than “Red” states (an average of B− vs D−). “Blue” states also have lower homicide rates than “Red” states (4.5 vs 5.9), and this is statistically significant (p = 0.012). There is a weak (R2 = 6%) correlation between gun laws and homicide rates, but this relationship is not statistically significant.

Whatever it is that makes you less likely to be murdered in some states than others, it does not primarily seem to be the gun laws. Poverty may be one of the relevant factors, however – median household income explains 22% of the variance in homicide rates, and when this is taken into account, any effects due to gun laws or election results disappear. “Red” states are, on the whole, simply poorer (and, conversely, poor states are more likely to vote Republican and have weak gun laws). Other demographic factors, such as the number of people with college degrees, also seem to have explanatory value as far as the murder rate is concerned. However, the phenomenon of murder does not seem to be understood as well as it could be.


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The Three-Body Problem trilogy: a book review


The Three-Body Problem trilogy by Liu Cixin

I recently read (in translation, of course) the popular The Three-Body Problem science fiction trilogy by Liu Cixin. These books explore the idea of first contact, and touch on several topics that I have posted about before (such as the Fermi paradox and the 3-body problem itself). I enjoyed reading them (the first two books more than the third). It was fascinating to read a Chinese view on some of the issues explored.

The novels are somewhat darker than classic Western science fiction, largely due to the shadow cast by the Cultural Revolution. But given the possibility of aliens like the Borg, the Daleks, and the Vang, perhaps interstellar optimism is just naive. And apparently, most contemporary Chinese science fiction is even more pessimistic than that of Liu (one of the characters in the first novel comments on this).

It seemed a little strange that Liu accepts the speed-of-light limit on space travel, but allows faster-than-light communication (which other authors have called an ansible). After all, both relativity and quantum mechanics forbid such a technology. Still, any depiction of truly advanced technology is going to read like fantasy, and the plot did require an ansible (although partway through the trilogy, the speed-of-light limit seemed to vanish even for ordinary communication).

These books (at least the first two) are well worth a read. Wired magazine also posted a review last year, and Nature had an interview with the author.


The Three-Body Problem trilogy by Liu Cixin: 3.5 stars


Logic in a box!

Having recently spent some time teaching a short course on logic and critical thinking, here is the core of the course reduced down to a box of 54 cards. These include:

  • 15 logic cards (summarising basic syllogistic and propositional logic rules),
  • 19 cards illustrating logical fallacies,
  • 5 cards for testing your ability to check validity, and
  • 15 logic-puzzle cards.

If you’re interested, more details can be downloaded from the game page (see the links in the “Downloads” section). The picture below shows some of the cards:


The moons of Saturn

In honour of the Cassini probe, the diagram above shows (to scale) the larger moons of Saturn (those over 100 km in diameter). The moons are shown in order of distance from Saturn, with Janus and Epimetheus being the closest. Titan comes between Rhea and Hyperion.

Janus, Epimetheus, Mimas, Rhea, and Phoebe are shown in black-and-white. Enceladus, Tethys, and Dione are shown in enhanced colour (combining infrared, visible, and ultraviolet). Titan is shown in infrared, which penetrates the atmospheric haze. Hyperion is in true colour, and Iapetus in false colour. Click on the image to zoom.


American Solar Challenge: 8 months away

The American Solar Challenge will be held next July, and I have put together an annotated teams list for that event. Following qualification at Motorsport Park Hastings, Nebraska, the race will run through the mountains from Omaha, Nebraska to Bend, Oregon. The map above shows the approximate route on an elevation map of the northwest US. It will be interesting to see how the solar cars cope with the uphill climb


Origins of the alphabet

This chart shows the origins of the Phoenician, Hebrew, Greek, and Latin alphabets. The Phoenician alphabet is adapted from Egyptian hieroglyphs, but the exact pictorial origins are rather uncertain. The specific Phoenician alphabet used is from here. The chart was produced using R.