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October 16, 2009

Girih by Egan

Posted by John Baez

Check out Greg Egan’s new Girih applet that generates quasiperiodic tilings with ten-fold rotational symmetry, using a method called "inflation". You’ll see patterns like this, that keep zooming in endlessly…

Though quasiperiodic tilings are often attributed to Penrose, in fact they were discovered in the 15th century by the Timurids: a dynasty of Mongol origin who ruled over a large empire in Central Asia, Persia and Mesopotamia. This fact was rediscovered by Peter Lu and Jacob Steinhardt. Egan saw designed related to the above one on a mosque in Isfahan during a trip to Iran. What was he doing in Iran? Researching his latest novel, Zendegi.

“Girih”, or “strapwork”, is the name for the braid-like patterns that the Timurids used to decorate their designs. Here is a set of five tiles used to make designs with 5- or 10-fold quasisymmetry:

Posted at October 16, 2009 12:05 AM UTC

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quasicrystals and CQG? Re: Girih by Egan

Beautiful when static, more so when dynamic. The Math journals have been tracking the story. It seems unlikely that anyone in the 15th century saw these in terms of 2-D slices through 4-D or higher periodic tessellations, nor understood quasicrystals. Nor, for that matter, beat Penrose and John Lucas to the punch with belief that deterministic non-algorithmic processes may come in play in the quantum mechanical wave function reduction, and may be harnessed by the brain. Nor with “correct quantum gravity,” CQG. But if Greg Egan puts that into fiction, I’ll willingly suspend disbelief.

Posted by: Jonathan Vos Post on October 16, 2009 5:12 PM | Permalink | Reply to this

Re: Girih by Egan

You can now order Egan’s novel Zendegi from Amazon. It turned up in my list of recommendations today!

Here’s a summary:

In 2012, journalist Martin Seymour travels to Iran to cover the parliamentary elections. With most would-be candidates disqualified this turns out to be the expected non-event, but shortly afterward a compromising image of a government official captured on a mobile phone triggers a political avalanche. Nasim Golestani, a young Iranian scientist living in exile in the United States, is hoping to work on the Human Connectome Project – which aims to construct a detailed map of the wiring of the human brain – but when government funding for the project is cancelled and a chance comes to return to her homeland, she chooses to head back to Iran. Fifteen years later, Martin is living in Iran with his wife and young son, while Nasim is in charge of the virtual world known as Zendegi, used by millions of people for entertainment and business. When Zendegi comes under threat from powerful competitors, Nasim draws on her old skills, and data from the now-completed Human Connectome Project, to embark on a program to create more life-like virtual characters and give the company an unbeatable edge. As controversy grows over the nature and rights of these software characters, tragedy strikes Martin’s family. Martin turns to Nasim, seeking a solution that no one else can offer … but Zendegi is about to become a battlefield.

Egan wrote this book before the last election and the massive protests that followed. As I’ve probably mentioned somewhere, he visited Iran to research Zendegi in October of 2008, and you can read his travel diary here.
Posted by: John Baez on May 9, 2010 12:59 AM | Permalink | Reply to this

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