Archive for February 17, 2009

Chinese Puzzles

Posted in Uncategorized with tags , , on February 17, 2009 by telescoper

On Friday 13th February I made one of my sporadic trips to London to go to the Royal Astronomical Society monthly meeting, catch up with friends, and dine at the Athenaeum with the RAS Club. That also gave me the excuse to stay in London over Valentine’s day and go with an old friend to the Opera followed by dinner in Chinatown on Saturday night.

As it happens, the RAS meeting also had a taste of the Orient about it because there were two absolutely fascinating talks about the Dunhuang Star Chart. This is a paper scroll found amongst many thousand similar objects squirrelled away by Buddhist monks in a tomb which was then subsequently bricked up and painted over. It lay undisturbed for a thousand years until rediscovered and basically plundered by treasure hunters, adventurers and archaeologists and its contents dispersed around the globe.

The Dunhuang Star Chart thus found its way to the British Library in London where it has recently been the subject of a special study involving both historians and astronomers. You can see this huge and very ancient sky map in full online here.

I had read about this sky map before in some book about the history of astronomy, but I hadn’t realised that its date had recently been re-evaluated to put it not in the 10th century (as I had previously believed), but in the middle of the 7th centur,  possibly as early as 640 AD. Moreover, recent quite convincing mathematical analysis has shown that the chart is not just made of freehand sketches but was produced with some mathematical precision using a form of cylindrical projection. Once again, we find the Chinese were well in advance of their western counterparts in terms of scientific knowledge.

So why were these scrolls hidden away? There are two theories. One is that the monks were concerned about imminent invasion from the west and they simply wanted to safeguard their knowledge until it could be reclaimed. Unfortunately it never was. The other theory is based on the fact that astronomical knowledge was highly classified in this period of Chinese imperial rule, the Tang Dynasty. The astrological clues contained in star charts could be used to cast doubt on the Emperor if they fell into the wrong hands, so were  forbidden to all but the inner court. Astronomy was Top Secret. The monks at Dunhuang may have hidden their papers because they shouldn’t have had them in the first place, and feared the wrath of the Emperor if they  were discovered by the Imperial heavies.

I find mysterious artefacts like this absolutely fascinating and they also strengthen my conviction that astronomy and archaeology have much in common. Both are observational rather than experimental sciences, and both rely on making inferences based on indirect and sometimes scanty clues. Perhaps its this that makes both disciplines prone to a few flights of fancy every now and again as well as posing puzzles which perhaps will never be solved.

Anyway, topping the bill at the RAS was the President, Andy Fabian, whose Presidential Address was entitled Black Holes at Work. Unfortunately,  the thing that didn’t work was the data projector so we had an embarassing delay while people rushed around trying to fix it. One of the charms of the RAS is that it never seems to be quite at the forefront of  technology. Anyway, once he got going the talk was very interesting. He was short of time at the end, though, so I didn’t have time to ask the  obligatory question about magnetic fields.

Then it was down to the Atheneaum and a nice dinner and rather a lot to drink.

The following evening after the Opera we went for dinner in Chinatown in Soho. The chilly West End streets were crowded, with what I originally assumed to be Valentine dates but which appeared instead to be mainly standard tourists taking advantage of the weak pound. Many restaurants were completely full, but eventually we found a table in a good place and all was well.

Coming back to Cardiff the following day I bought the Observer so I could do the crosswords on the train, and was reminded of the Azed competition crossword a couple of weeks ago which involved a quotation from a poem about St Valentine’s day by Coventry Padmore. It was quite a strange puzzle of a type called “Letters Latent” in which the cryptic part referred to the answer minus one or more letters.  The quote concerned was

Well dost thou, Love, thy solemn Feast to hold
In vestal February;

the poem is trying to make the point that wintry February is  a good time for St Valentine’s day as during spring and summer nobody needs to be reminded about the birds and the bees.

The task for competition entrants was to clue the word “vestal” in such a way that the definition referred to the whole word but the cryptic part omitted the s. My attempt was

Volatile components make this oil extra virgin

(The components of volatile give oil+vetal; virgin is the definition for vestal.)

Since I’ve now meandered far off the original subject, I think I’d better finish there!

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