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Agent of change
February 27, 2005
Cole Cr#%
Juan Cole is an indispensable source of information and insight into the situation in Iraq. He really knows the country, and collates an impressive amount of information from both the Western and Arabic Press.
His blog is compelling reading, but it would be that much more compelling, if it were not laced with tendentious crap like
AP reports that the one-day total for war-related violence in Iraq, including the police station bombing in Tikrit reported here yesterday morning, came to 30. That is about 11,000 persons a year if the rate were constant and extrapolated out.
Do you really want to take a one-day death count (and an anomalously high one, at that) and extrapolate that forward for a year? Do you think the resulting number has any meaning?
With a couple of minutes more work, you could take a 5-day running average death count (as reported on his blog and cross-referenced with iraqbodycount) and extrapolate that number forward. Isn’t 4745 deaths/year bad enough?
Given the inadequacies of the reportage, it’s likely to be an underestimate. But, at least, it won’t be instantly dismissed — by any reader with an ounce of sense — as a statistical fluctuation.
Conversations with Greg
Greg Moore was in town for a few days, and we had — as always — some very interesting discussions. Among the topics was his recent paper with Dabholkar, Denef and Pioline.
I’ve talked before about the Ooguri-Strominger-Vafa proposal relating the entropy of a charged black (which appears as a nontrivial solution of type-IIA strings compactified on some Calabi-Yau, ) to the topological string partition function for the same Calabi-Yau. Specifically,
where , are the electric and magnetic charges, is the holomorphic topological string free energy, and is a microcanonical partition function — the number, or perhaps some index, of the number of states of charge .
There are three questions about this formula
- What contour of integration should be chosen (if one exists) so that the integral is well-defined?
- Exactly what is counting?
- Is the formula right?
February 23, 2005
Reinvention
Back in second grade, I was dissatisfied with the algorithm we were being taught for doing subtraction. So I “invented” my own
– 185
5 is bigger than 3, so we subtract them in the opposite order (5–3=2) and take the tens-complement (8) of the result. As usual, we borrow from the 6 (which becomes a 5) and we repeat: 8–5=3 and take the tens-complement (7). Finally 2–1=1, so the answer is 178.
While only slightly different from the conventional algorithm, I felt this one to be an improvement because I never had to know how to subtract from numbers larger than 10 (e.g. who cares what 13–5 is?).
I haven’t thought much about this little juvenile act of rebellion until a couple of months ago, when I was going over my daughter’s 3rd grade math homework with her. She was doing similar subtraction problems. But, in keeping with the times, she was charged with explaining her methods for arriving at the answer.
Imagine my surprise when she explained her method to me. It was exactly the same “unconventional” algorithm that I had used when I was her age. It was not what the teacher had taught; she had figured it out on her own.
[Her method was the same, but her accuracy was not the greatest. So I taught her the other trick that I learned in that era: check your work by doing arithmetic modulo 9: 178=1+7+8= 7 mod 9, 185=1+8+5=5 mod 9. So 178+185=5+7=12=1+2 = 3 mod 9, which agrees with 363=3+6+3=3 mod 9.]
Now, I don’t know what this has to do with Larry Summers’ remarks on the dearth of women in the Hard Sciences (at least in this country). My personal experience echoes that of the AIP Study. An alarmingly large majority of the women who arrived at Harvard the year I did, intending to major in Physics, had decided by sophomore year to do something else. As a consequence, it was unsurprising that, by the time I started graduate school, there was only one woman in an entering class of 28. Sean Carroll takes on the thankless task of confronting Summers hypotheses with the data. I’m afraid I can’t muster the energy.
I’m much too busy trying to nurture that spark of creativity in my daughter, hoping that, a decade from now, she doesn’t face the stark choice that my classmates at Harvard/Radcliffe faced a generation ago.
February 17, 2005
Internationalization and Trackbacks
The last straw was when I received a Korean trackback, encoded in euc-kr.
The Trackback Specification makes no mention of character encodings, and MovableType’s original implementation was blissfully ignorant of any such notion. The sender of a Trackback ping sent a string of bytes (which represented a string of characters in charset of his blog) and the recipient dutifully published that string of bytes on his blog. If the recipient’s charset happened not to be the same as that of the sender, well, then, the result was gibberish.
The most recent versions of MovableType convey the sender’s charset in the HTTP headers of the Trackback. But the recipient doesn’t actually do anything with the information.
As a result, I had a slowly increasing number of gibberish Trackbacks on my blog, with no end in sight.
If you want something done right …
February 16, 2005
Coming Soon to a Hard Drive Near You
Once upon a time, a megabyte was a lot of data. In 1989, when Joanne Cohn first started emailing preprints to a couple of hundred colleagues, people quickly found themselves exceeding their mail quotas. And not everyone was interested in every paper. So why waste bandwidth and precious disk space on all that junk?
The idea of centralizing the storage, and sending people only the papers they requested, prompted Paul Ginsparg to start the hep-th archive in 1991.
Flash forward 14 years.
250 GB hard drives are cheap, and a laptop with less than 60 GB seems positively claustrophobic. Hep-th has grown tremendously. But even with over two hundred submissions a month, it’s still a puny amount of data by today’s standards. The entire archive from 1991 to the present (8GB of PDF files) fits easily on an iPod.
So, in reversal of history, Joanna Karczmarek is gearing up to distribute the whole shebang via bittorent. She’s currently offering 2004 (pdf papers and a plain-text list of abstracts) as a modest 850 MB torrent.
A year’s worth of physics for your iPod Shuffle.
February 13, 2005
Words to Live By
“Don’t fire a gun while you’re driving a car.”
— my 9 year old daughter, admonishing her 4 year old brother