100 years since the Tunguska Explosion

The Tunguska Explosion took place on June 30th 1908, exactly 100 years ago today. Although it is almost certain that it was the result of an small asteroid or comet exploding in the atmosphere with an estimated yield(*) equivalent to 20 million tons of TNT (i.e. over a thousand times more energy than released by the atomic bomb dropped on Hiroshima), many mysteries still remain.

Scientific American had an interesting article on Tunguska in its June 2008 edition, on the search for a crater. Space.com has another article worth a look, which has some fun at the end by mentioning some of the more outlandish hypotheses put forward over the years: an alien space ship blowing up, a mini-black hole passing through the Earth, or Tesla's experimental death ray.

(*) The explosion of 1 ton of TNT is equivalent to the release of 4.18e9 Joules of energy (see here), so roughly the Tunguska explosion was about 8.4e15 Joules, or 8.4e22 ergs. By way of comparison the luminosity of the Sun is 3.845e33 ergs per second.

[The image is of trees flattened by the explosion, taken twenty years afterwards by the Kulik expedition. Source: APOD for 2007 November 14]

A short history of nuclear-powered aircraft

Shaviv at DailyKos provides an interesting summary of the unhappy history of nuclear powered aircraft designs, featuring the Convair X-6, the XB-70 Valkyrie (very 70's looking, as you can see from the Wikimedia Commons image, but still a beautiful bit of technology), and the un-manned nuclear ramjet Project Pluto.

Is anyone currently thinking big and trying to make ambitious outside-the-box stuff like this?

More evidence for ancient impactor as sources of Mars's North/South dichotomy

A variety of media outlets are reporting on a series of new papers that strengthen the case that the peculiar differences between the northern and southern hemispheres of Mars (e.g. see this topographic map of Mars, or this web page) are due to a very large impact by a proto-planetary object of order 1000 miles in diameter.

Kenneth Chang discusses this in an article in the NYT, although he awkwardly calls the impactor a "meteor." Clara Moskowitz at Space.com also discusses the story, as does JR Minkle at SciAm news (see if you can spot the mistake in the image caption accompanying the SciAm article).

[Image shown is a color-coded map of the elevation of Mars, from the Mars Orbiter Laser Altimeter, showing the low, smooth, northern hemisphere and the higher, cratered, south. Note that even recently (1999) this data was used to argue against an external cause for the north/south dichotomy.]

The Happy Conservative?

[Warning: This post is all about politics, and reflects the personal opinions of the writer. Don't read it if politics offends you.]

According to this SciAm podcast by Christie Nicholson ("Why are conservatives happier than liberals?"), new research investigating the reasons for why previous polling shows that conservatives tend to have greater subjective well-being than liberals has found that:

conservative belief acts as a psychological buffer in a world of increasing inequality. The idea is that conservatives tend to rationalize inequality as the result of a fair process in a meritocracy, whereas liberals tend to see inequality as inherently unjust.

Hum. Skeptical would be an understatement of how I feel about this sort of thing. This is exactly the sort of thing that makes the "hard" sciences look down on the the so-called "soft" sciences like psychology (despite them doing good science at other times).

Some polling is hardly a great empirical basis on which to base a result that one then seeks to elevate to a facet of psychology worthy of explaining. Polling depends heavily on exactly what questions are asked and what responses are allowed, is subject to all sorts of annoying sampling biases, and even then we know people's responses may not be entirely honest or robust.

Now there may be some truth in the quoted result - or at least it reinforces widely-accepted liberal views of conservatism. My favorite is a quote from John Kenneth Galbraith:

The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness.

Yet while this may be true in part, the input hypothesis accepted at face value in the research quote in SciAm - that conservatives are "happier" than liberals - is fundamentally one-dimensional and overly simplistic.


Anyone who has paid attention to politics in the last few decades (or has read conservative blogs such as Free Republic, Red State or LGF) will have seen that modern conservatism is strongly energized and supported not by superior subjective well being, but by anger and fear. The conservative voting base in the Western World is worried and unhappy about (and goes to vote against) women's increasing control over their own bodies, peoples increasing wish for freedom and rights regarding their own sexuality, increasing ethnic and religious diversity, and the erosion of the old white protestant domination of social, economic and political spheres.

Yes, there are many conservatives who are purely economically motivated, the (often undeserving or deliberately unethical) over-privileged wealthy, who personify the deliberate smug self-satisfaction described in the article. These people may even control their political parties.

But rank-and-file conservatives are not the happy go lucky caricatures presented in the cute 60 second podcast. I don't think I've ever met a conservative who wasn't deeply unhappy about some imagined societal injustice or social crisis. So for now I'll just take this latest take on "happy conservatives" with a big pinch of salt.