Wednesday, December 29, 2004

The Physicist Who Became Death

Quoting the Bhagavad-Gita, the holy book of the Hindus, J. Robert Oppenheimer said, "I am become Death, the shatterer of worlds" when he saw the large cloud of the test atomic bomb rising over the New Mexico desert in 1945. Thus he may be a devil for the people of Hiroshima and Nagasaki. However, he was, in a sense, a victim of the war himself. A commission to investigate his loyalty rendered in 1954 its judgment that Oppenheimer was unfit to serve his country, U.S.A. [1].

I have read an article "Remembering Oppenheimer: The Teacher, The Man" [2] by Edward Gerjuoy, professor of physics emeritus at the University of Pittsburgh. Gerjuoy describes the observation of Oppenheimer he made as a graduate student in the UC-Berkeley physics department from 1938 to 1942. I give here a much-abridged version of Gerjuoy's passages about Oppie's style of teaching (Gerjuoy have called Oppenheimer Oppie since his student days):

Oppie gave no final exams or any other tests. He did not designate a textbook for any of his courses (the hypermodern materials he taught could not be found in any of the then available textbooks). He delivered a class lecture at high speed along with numerous equations written on the board and chain smoking. His relations with his students were surprisingly informal. The seminar was Oppie's domain, his fiefdom. Despite his sometimes overly ferocious questioning, his students respected him and felt indebted to him. ...

The physicist who became Death had a good face as a teacher of physics. Some classmates of mine at a university knew very well about textbooks on physics, and said that one of the best textbooks for electrodynamics was Oppie's. At that time (late 1950s) I sought a Japanese translation of that book at bookstores, but could not find one. I now find an English edition (possibly a revised edition) at Amazon [3].

By the way, many famous physicists were also a good teacher and ferocious questioner at the seminar. I liked to organize seminars in my work years at an institute and a university, and wanted to be a ferocious questioner, though I may not have been successful in it.
  1. J. Daintith, et al. ed., Biographical Encyclopedia of Scientists, 2nd edition (Institute of Physics Publishing, Bristol, 1994).
  2. E. Gerjuoy, APS News, Vol. 13, No. 10, p. 8 (November 2004).
  3. J. R. Oppenheimer, Lectures on Electrodynamics (Gordon & Breach, 1970) (Out of print--limited availability).

Tuesday, December 28, 2004

Math Could Help Art History

Authors of novels have been identified through context-free word counts. Similarly, one might be able to identify painters by analyzing the frequency of certain types of curves. This was the idea of the mathematician Hany Farid and two colleagues at Dartmouth College in Hanover, New Hampshire, U.S.A. [1].

They have developed an approach that builds a statistical model of an artist from the scans of a set of authenticated works against which new works are compared. The statistical model consists of first- and higher-order "wavelet decomposition." They have analyzed 13 (8 true and 5 false) drawings that have been attributed to the 16th century artist Pieter Bruegel the Elder, and have gotten the results that confirm expert authentications [2].

The researchers have also applied these techniques to determining the number of artists that may have contributed to the painting "Madonna with Child" attributed to the 16th century Italian painter Pietro Perugino, and again have achieved an analysis agreeing with expert opinion [2].

This indicates the possibility that the computer can help research in art history, rendering one of examples of cooperation between arts and science in a broad sense.
  1. "Verifying art with math" Science, Vol. 306, 1678 (2004).
  2. S. Lyu, D. Rockmore and H. Farid, Proc. Natl. Acad. Sci. Vol. 101, 17006 (2004).

Thursday, December 16, 2004

All Humans Share a Close Relation II

A reader of my previous blog [1] has told me about the origin of the idea that six times of tracing of acquaintanceship covers almost all the people the world over. It is the concept termed "six degrees of separation" proposed by the American social psychologist Stanley Milgram (1933-1984) in 1967.

Searching the name of this concept by Google, I found a piece of Web site news [2] about an experiment related to the concept. From this piece of news I noticed this: It was the original article [3] on this experiment published by Duncan Watts and colleagues at Columbia University in New York that was vaguely in my memory and made me write the blog mentioned above.

In the experiment by the researchers at Columbia University more than 60,000 people from 166 different countries took part. Participants were assigned one of 18 target people, and were asked to contact that person by sending email to people they already knew. The researchers found that in most cases it took between five and seven emails to contact the target. The result did not indicate that the email had made the world a more close-knit community, but confirmed the validity of Milgram's concept, which had emerged from a similar postal experiment [2].
  1. "All humans share a close relation" (2004).
  2. W. Knight, "Email experiment confirms six degrees of separation" News Service (Aug. 7, 2003).
  3. P. S. Dodds, R. Muhamad, D. J. Watts, "An experimental study of search in global social networks" Science, Vol. 301, p. 827 (2003).

Wednesday, December 08, 2004

All Humans Share a Close Relation I

I read a story like this somewhere: If we trace acquaintanceship starting from a single person to that person's acquaintances, to the acquaintances of those acquaintances, to the acquaintances of those acquaintances' acquaintances, etc., then six times of this tracing covers almost all the people around the world (I'm not sure about the number six, but the calculation explained below shows that this is a reasonable number). Only six times! It means that all humans are in a rather close relationship.

A simple calculation convinces us of the above story. I send New Year and Christmas cards to a total of more than 150 people. I have much more acquaintances than this number, because I also know families of some friends of mine and have acquaintances to whom I don't send the cards. However, this number is possibly much larger than the average number of a person's acquaintances if we take small children and babies into account. Therefore, I divide 150 by 3, and assume the average number of acquaintances to be 50. Tracing acquaintances with this assumed number makes the number of people increase by the multiplication factor of 50 at each step. The final number becomes 506.

Actually, there is overlapping of acquaintances, so that the number does not increase this fast. But I already made a mean estimate in choosing the number 50. Further, this is a rough calculation to find the order of magnitude. So, believe that the final number shown above is a good estimate. That number is calculated to be about 16 billion. The population of the world is about 6.4 billion. Thus the former well covers the latter. Q.E.D.

I thought of this close human relationship from the word "friends of friends of yours" in the e-mail messages of the social networking service "Echoo!" I have joined.

Monday, December 06, 2004

"Blog" Top Word of 2004

U.S. dictionary publisher Merriam-Webster Inc. announced on November 30 its "Words of the Year 2004" [1]. These are determined by the statistics of online lookups at the publisher's Web sites. The No.1 Word of the Year was:
Blog noun [short for Weblog] (1999): a Web site that contains an online personal journal with reflections, comments, and often hyperlinks provided by the writer
Blog will be a new entry in the 2005 version of the Merriam-Webster Collegiate Dictionary, Eleventh Edition.

The other words in the top-ten list are as follows:
 2. incumbent
 3. electoral
 4. insurgent
 5. hurricane
 6. cicada
 7. peloton
 8. partisan
 9. sovereignty
10. defenestration
Eight entries among the top ten is related to major news events from the presidential election to natural phenomena.

How many of the above words do you know? Clicking these words at the Merriam-Webster OnLine site provides their definitions.

The year 2004 was just the year when I began to use blog sites.
  1. Publisher: 'Blog' No. 1 word of the year, (November 30, 2004).