Wikipedia articles of interest

1. Yardang.

“A yardang is a streamlined hill carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion, dust and sand, and deflation.[1] Yardangs are elongate features typically three or more times longer than they are wide, and when viewed from above, resemble the hull of a boat. Facing the wind is a steep, blunt face that gradually gets lower and narrower toward the lee end.[2] Yardangs are formed by wind erosion, typically of an originally flat surface formed from areas of harder and softer material. The soft material is eroded and removed by the wind, and the harder material remains.”

See also this and this for related stuff.

2. T-34.

3. Endogamy. The Wiktionary says endogamy is: “The practice of marrying or requiring to marry within one’s own ethnic, religious, or social group.” The article has more. Didn’t know there was a name for this.

4. Factor analysis (somewhat study/exam-related).

5. History of paper.

“Toilet paper was used in China by at least the 6th century CE.” I had no idea it’s been around for that long! Also:

“The earliest recorded use of paper for packaging dates back to 1035, when a Persian traveler visiting markets in Cairo noted that vegetables, spices and hardware were wrapped in paper for the customers after they were sold.[20]”

Latest xkcd-strip which I thought I ought to add here:

Btw, I think Randall Munroe perhaps does not spend much time around people with average IQ’s, if the RHS is supposed to illustrate that 30 point drop. The average IQ of people who don’t know what a car is, well, it’s pretty damn low (most of them also probably can neither read nor write). The learned helplessness (‘why should I remember this when I can just look it up’) aspect of tech is important, but that comic was too much over the top to do it for me.

Incidentally, the drop (which is real and significant for me too) is part of why I almost prefer to interact with people online rather than in person. I have the impression that real-time face-to-face interaction is not exactly where I have my comparative advantage. Online interaction also makes discussions with a significant knowledge-component much easier to engage in, and the lag/delay between idea exchanges which is often a part of that interaction makes sure people like me, who perhaps aren’t really all that quick on the uptake, have time to think things more through. It goes both for ‘pure ideas’ and it goes for implicit social rules and norms which I sometimes have a hard time remembering implementing when doing the face-to-face stuff because there’s not enough time to both have the conversation and be aware of all that other stuff.

May 25, 2011 - Posted by | Geology, history, personal, statistics, wikipedia


  1. En billedgoogling på yardang var også umagen værd, omend det mere er en æstetisk oplevelse.

    Comment by info | May 25, 2011 | Reply

  2. To mennesker, en tanke. Jeg overvejede faktisk at tilføje et link til google’s billedsøgning af ordet da jeg skrev posten, men mente så at det kunne blive lige rigeligt med links på en gang (der findes et punkt, hvor det ekstra marginale link betyder færre kliks i alt, i stedet for det modsatte, og jeg tænkte at jeg var i nærheden af det punkt).

    Comment by US | May 25, 2011 | Reply

  3. Re T-34: I think the Wiki article does not give the due attention to the sloped armor of the T-34. The German Panzer divisions were the backbone of the German blitzkrieg doctrine – they rolled over everything opponents had set against them before the Russian fiasco, while virtually invulnerable. They also did it at high speed – advancing 50km a day into an enemy’s territory is devastating, except in Russia – and even there it was close. [Side note: that speed of advance in Russia was actually a part of the failure of the Barbarossa plan – the German supply lines became stretched too thin, and vulnerable to the massive Russian guerrilla movement. You need a lot of fuel to run armor divisions.] As a result, the Panzer commanded a huge fear factor, and it’s hard to overestimate the effect of morale in a war. With the advent of the T-34, the morale dynamic was turned on its head – now the Germans were watching in terror and disbelief how the Panzer shells bounced off the T-34, while the T-34s were happily collecting Panzer scalps. Combine this with the Katyusha BM-13s (often mounted on US Studebaker US6 trucks) that could, for a battery of four trucks, lay down over 4 tons of high explosive over a 200×200 meter area in 10 seconds in a checkerboard pattern, and all of a sudden every German advance was a reason for the Germans, not the Russians, to soil their underwear.

    Re the xkcd strip: I understand that your use of “learned helplessness” is a metaphor, but I think it’s a little too harsh, as it implies a (strong?) negative aspect to not having to memorize copious details about various subjects, rather than general ideas plus a reference to the location of more details available as needed. I really see no downside to it, excluding situations where you have no access to the knowledge repository – but in the modern world, if that were to happen, you’d have more pressing problems at hand, like where to find a safe haven from the nuclear apocalypse, or what the most effective way to dispatch zombies is. I am totally with you as to the preference for online communication. I think what may be lost in terms of speed of communication is more than made up for in terms of quality of the ideas exchanged. Interestingly, my problem (with real-time communication) seems to be the opposite of yours. I am not slow on the uptake, but too fast (i.e. rash) on the uptake. I have found myself in a position of adopting a position quickly, and then defending it (often effectively) blinded by confirmation bias, when further research totally has changes my mind.

    Comment by Plamus | May 26, 2011 | Reply

  4. When you mentioned it, I remember reading about the sloped armour aspect as well. If you have a source at hand (I haven’t, because I believe the book where I read about that stuff a few years ago is one I at one point borrowed from my brother, and he lives hundreds of kilometers away), consider adding some remarks about this factor in the article; that’s part of how wikipedia improves.

    “learned helplessness” is a bit harsh, yeah, I know. The internet also means you no longer have to walk around remembering all kinds of marginally relevant stuff and can instead use your brain for more productive purposes like connecting the dots. Unless of course you’re a student who wants to pass your exams in order to signal your (in the job-market mostly irrelevant) ability to remember (irrelevant) stuff (much of which is made artificially hard by conventions and academic norms) (sorry: in order to display ‘your level of intelligence and conscientiousness’).

    I can be rash too, but that’s also because I’m slow; if I was able to think faster, I like to think I’d be communicating at the same speed but contributing more and/or displaying more socially optimal behaviour. In general I like to tell myself that I’m deliberately trying to slow myself down and not speak too much, because I can talk a lot when I get excited about something. I also know this is partly a lie I tell myself, because I usually end up contributing far more to a random conversation in which I decide to participate actively than I’d intended beforehand. But if one were to compare me to the me that was five years ago, I think I’ve become a lot better at holding back and I’m quite happy about that.

    One of the things I think I’ve been coming more to terms with over time is the fact that social behaviour which impacts how others perceive you when you’re having a conversation with them also indirectly affects the quality of the discussion, and not always in a good way, but even if that’s the case it can sometimes be optimal to opt for the marginally lower quality exchange due to long run considerations. Sometimes the polite thing to do is to just let the fool speak even if it’s unpleasant to listen to that stuff, but not only is it the polite thing to do, it’s also part of the implicit social contract which makes those interpersonal interactions work; if you let the fool (the guy you disagree with) speak, he’s more likely to do the same when you’re the fool (-ll-) talking. There’s a cost related to listening to nonsense, but there’s also a cost to not being listened to at all.

    Anyway, I tend to believe that in the verbal setting disagreement tends to breed conflict, because a lot of what goes on in a discussion is just signalling and posturing ect. If you disagree it’s easy and natural for the other individual to conclude that you’re implying that you’re a higher status individual, and if he doesn’t contest this you end up with the female, you get to have children and he doesn’t – we’ve been playing these games for millions of years, language just added one more contest parameter to the mix. Status and correlated factors really matter a lot. A related concern is that in general I consider verbal discussions to be much less honest than discussions which takes place in writing. It’s more risky spouting bullshit or lying if you can just deny you ever said whatever you might have said the next day, than if the other guy has all your statements written down.

    Comment by US | May 26, 2011 | Reply

  5. Speaking of armor, one of the cooler things I read in Needham’s _Science and Civilisation in China_ was the early Chinese using paper armor.

    Comment by gwern | October 22, 2011 | Reply

    • 🙂

      Presumably they got smarter along the way…

      Comment by US | October 22, 2011 | Reply

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