Archive for China

the three-body problem [book review]

Posted in Books with tags , , , , , , , on February 5, 2017 by xi'an

“Back then, I thought of one thing: Have you heard of the Monte Carlo method? Ah, it’s a computer algorithm often used for calculating the area of irregular shapes. Specifically, the software puts the figure of interest in a figure of known area, such as a circle, and randomly strikes it with many tiny balls, never targeting the same spot twice. After a large number of balls, the proportion of balls that fall within the irregular shape compared to the total number of balls used to hit the circle will yield the area of the shape. Of course, the smaller the balls used, the more accurate the result.

Although the method is simple, it shows how, mathematically, random brute force can overcome precise logic. It’s a numerical approach that uses quantity to derive quality. This is my strategy for solving the three-body problem. I study the system moment by moment. At each moment, the spheres’ motion vectors can combine in infinite ways. I treat each combination like a life form. The key is to set up some rules: which combinations of motion vectors are “healthy” and “beneficial,” and which combinations are “detrimental” and “harmful.” The former receive a survival advantage while the latter are disfavored. The computation proceeds by eliminating the disadvantaged and preserving the advantaged. The final combination that survives is the correct prediction for the system’s next configuration, the next moment in time.”

While I had read rather negative reviews of the Three-Body Problem, I still decided to buy the book from an Oxford bookstore and give it a try. Ìf only because this was Chinese science-fiction and I had never read any Chinese science-fiction. (Of course the same motivation would apply for most other countries!) While the historical (or pseudo-historical) part of the novel is most interesting, about the daughter of a university physicist killed by Red Guards during the Cultural Revolution and hence forever suspect, even after decades of exile, the science-fiction part about contacting another inhabited planet and embracing its alien values based on its sole existence is quite deficient and/or very old-fashioned. As is [old-fashioned] the call to more than three dimensions to manage anything, from space travel to instantaneous transfer of information, to ultimate weapons. And an alien civilization that is not dramatically alien. As for the three body problem itself, there is very little of interest in the book and the above quote on using Monte Carlo to “solve” the three-body problem is not of any novelty since it started in the early 1940’s.

I am thus very much surprised at the book getting a Hugo award. For a style that is more reminiscent of early Weird Tales than of current science-fiction… In addition, the characters are rather flat and often act in unnatural ways. (Some critics blame the translation, but I think it gets deeper than that.)

Pu Erh [普洱茶]

Posted in pictures, Travel with tags , , , , on October 1, 2016 by xi'an

Two massive pancakes of Pu Erh (Pǔ’ěr) [fermented] tea my student Changye brought me back from Yunnan (made by the factory that revolutionised the making of Pu Erh) and that I am looking forward tasting!

Le Monde puzzle [#848]

Posted in Books, Kids, Statistics with tags , , , on December 28, 2013 by xi'an

The X’mas version of Le Monde mathematical puzzles:

A shop sells X’mas trees (with 25 models which prices range from 36€ to 65), X’mas fairy lights (with 18 models which prices range from 6.50 to 27), and X’mas balls (with 13 models which prices range from 9 to 17.50). A lot is made of a model from each group. Is it possible to set the prices so that all different lots have different total prices ? Differences are expressed in cents.

It would be straightforward to set an R code picking 25x18x13=5850 prices at random until all sums are different or a maximal number of trials is reached… but the maximal number of values for the total prices is

100x(65.01-36)+100x(25-6.49)+100x(17.51-9)=5803

so this proves impossible to satisfy. No wonder the title of the puzzle is “A X’mas gift”! (The most interesting entry in this issue of the Science leaflet is an impressive photo of an amputated hand grafted on a leg by Chinese surgeons while waiting for the damaged arm to recover. Maybe too impressive at X’mas dinner time…)

“Dry Red Wine”

Posted in Travel, Wines with tags , , , on June 20, 2011 by xi'an

A “dry red wine” (which exact name I do not know) I would certainly not recommend. The year (1994) is very unlikely to be related with the age of the beverage and the “Produce of France” at the bottom is at best connected to the use of French oak barrels…

上海, 天际线 [Shanghai skyline 2]

Posted in pictures, Travel with tags , , on June 16, 2011 by xi'an

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Snapshots from 上海

Posted in pictures, Travel with tags , , , , , on June 15, 2011 by xi'an


Before joining the O’Bayes 2011 conference, Linda kindly took me on a quick morning tour of the Bund, the historical colonial district of Shanghai. This was very nice, bringing back memories of my friend José de Sam Lazaro telling me about his childhood there in the French concession, and the views of the Huangpu River in a mist [that did not lift for the whole day] were terrific. (The photo below not only gives an hazy idea of the Pudong district, but it incorporates a well-hidden statue of the former mayor of Shanghai in typical Maoist attire, as well as a few security cameras that seem to be everywhere.) However, I felt a bit sorry (and not only from a tourist’s point of view) that there was no visible remnant of an older Shanghai (I mean, older than the colonial buildings on the Bund) that seemed to have been entirely razed to build new tall buildings in a rather haphazard fashion… The whole city is brimming with construction work, from high-rise buildings in the centre to the many housing complexes I saw from the highway.


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上海, 天际线 [Shanghai skyline 1]

Posted in pictures, Travel with tags , , , on June 14, 2011 by xi'an

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