Monthly Archives: September 2009
Doing it Right
Illuminating physics for students by David Griffiths
Physics teachers are fortunate (I am among friends, so I can speak frankly): ours is a subject the relevance and importance of which are beyond question, and which is intrinsically fascinating to anyone whose mind has not been corrupted by bad teaching or poisoned by dogma and superstition. I have never felt the need to “sell” physics, and efforts to do so under the banner “physics is fun” seem to me demeaning. Lay out our wares attractively in the marketplace of ideas and eager buyers will flock to us.
What we have on offer is nothing less than an explanation of how matter behaves on the most fundamental level. It is a story that is magnificent (by good fortune or divine benevolence), coherent (at least that is the goal), plausible (though far from obvious) and true (that is the most remarkable thing about it). It is imperfect and unfinished (of course), but always improving. It is, moreover, amazingly powerful and extraordinarily useful. Our job is to tell this story – even, if we are lucky, to add a sentence or a paragraph to it. And why not tell it with style and grace?
Griffiths came down to Corvallis and gave a talk when I was in grad school. It was pretty good — I felt like I almost understood Berry’s phase when he was done. (OSU had its own David Griffiths; fortunately they did not annihilate upon meeting)
I found a particular resonance with this comment
I have known people who are in some sense too smart to be clear; they cannot remember what it was like not to understand something, because, I suppose, they never had this experience. They may be outstanding physicists, but they do not belong in the classroom.
When I was teaching, and later when merely explaining, I’ve tried to understand the misconceptions people have, and the barrier that the misconceptions create. It’s not enough to tell someone that their answer is wrong — they need to understand why it’s wrong, too. Remembering what it was like to not understand something is really useful.
Reverse the Polarity!
Letting it All Hang Out
xkcd blag: Urinal protocol vulnerability
Packing efficiency applied to the urinal utilization protocol
The protocol is vulnerable to producing inefficient results for some urinal counts. Some numbers of urinals encourage efficient packing, and others encourage sparse packing.
Hoist on their own Petard
List of inventors killed by their own inventions
Thomas Andrews (1873 – 1912) died with 1,516 others when his innovative, “unsinkable” design for the RMS Titanic proved to be much more sinkable than he had anticipated.
This is Probably a Really Bad Idea
For me, anyway. My handwriting is pretty bad.
Create a font from your own handwriting
My (first) attempt, in which I did not pay much attention to the ascender and baseline marks.
The Speed of Information
Kottke: The speed of information travel, 1798 – 2009
The included link is chart showing the time it took for news of various events to reach London, and the resulting speed of that information. Kottke adds a couple of present-day data points to that.
[W]e’re not accustomed to news taking days or even hours to go around the world now, and even when reading history you usually get the impression that events were known immediately. (The dramatic speeding up of news reports around 1880 was a result of the invention and deployment of the telegraph.)
Certainly anyone growing up now, with access to twitter and the like, will have some difficulty appreciating this.
I think it’s easy to forget that it also takes time to gather information, especially for complex events. We have virtually instant access these days with electronic communication, but instant access to what? You can tell me that X happened, but then there’s a whole lot of dead air to fill while you figure out what the details were, and we shouldn’t forget that bad information travels just as fast.
One Giant Lie for Mankind
The Onion: Conspiracy Theorist Convinces Neil Armstrong Moon Landing Was Faked
Although Armstrong said he “could have sworn” he felt the effects of zero gravity while soaring out of the Earth’s atmosphere and through space, he now believed his memory must be flawed. He also admitted feeling “ashamed” that he had failed to notice the rippling of the American flag he and Buzz Aldrin planted on the surface, blaming his lack of awareness on the bulkiness of the spacesuit and his excitement about traveling to the “moon.”
“That rippling is not possible in the vacuum of space,” Armstrong said. “It must have been the wind from an air-conditioning duct that I didn’t recognize because you can’t hear a damn thing inside those helmets.”
Getting Loopy
Rhett analyzes a loop-the-loop; This is the same stunt (or is basically identical to the same stunt) I blogged about in May because the newspaper story summarizing it was so awful. But Rhett has graphs and charts and twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one is. So check it out.
And Matt has the same topic but with half as many wheels, in Diavolo riding the loop on a bicycle.
Blown Up, Sir!
I don’t recall how the conversation arrived on the topic, but I was explaining that one could use explosives to tenderize meat to some colleagues recently, and had to go find the story on the interwebs. And so I share with you:
Ka-Boom! A shockingly unconventional meat tenderizer
The idea of bombing meat came to Long some 30 years ago, while he was floating in his backyard pool. A mechanical engineer at Lawrence Livermore (Calif.) National Laboratory, he worked as an explosives expert on the design of triggering mechanisms for nuclear weapons. He was very familiar with conventional explosives and the shock waves created when they go off.
“My body has about the same density as the water,” he observed, “so if somebody threw a bomb into my pool, the shock waves should go right through me.” He started thinking about what those shock waves might do to his muscle — or to a piece of steak. To find out, he recruited friends for an experiment at a privately owned explosives testing site a few miles away.
They sliced a piece of tough beef in two, bagged half of it in plastic, and dropped it into the bottom of a 50-gallon paperboard drum of water. Then they suspended conventional explosives in the water and retired to a nearby bunker. From there, they watched in safety as a television displayed the ensuing detonation.
“The drum totally disappeared. There were just little pieces of paper fiber all over,” Long recalls. The meat, ejected to the side of a nearby hill, was missing for fully 15 minutes.
Once the treated meat had been retrieved, Long cooked it, along with its untreated counterpart, on a grill he had lugged to the site. The unshocked meat proved “so tough you could hardly chew it,” Long says. “But the one we shocked — it was delightful, as tender as a $10 steak in those days.”
This article is a decade old, but Long has been busy. He has several patents relating to the process.