Sunday, May 20, 2012

Fermat's Last Theorem in Autumn


A quiet Sydney autumn weekend was a perfect opportunity to re-read Azcel’s 1996 book - Fermat's Last Theorem: Unlocking the Secret of an Ancient Mathematical Problem. This book has been reviewed countless times with most expressing delight in how Azcel manages to describe the making of the proof with all of its red herrings, clues and suspense not too dissimilar to a mystery novel.

I also wanted to look at the interview Andrew Wiles gave Nova in 2000. I found re-reading Azcel’s book alongside the insights shared in this interview made the journey as exciting as the first time I read the book as well as help clarify Wiles’ motivation, and how a chance conversation about Ribet's Taniyama-Shimura and Fermat's Last Theorem connection with a friend would change the course of his life.




Wiles thought that nobody had any idea how to approach Taniyama-Shimura but at least it was mainstream mathematics. He could try and prove results, which, even if they didn't get the whole thing, would be worthwhile mathematics. So the romance of Fermat, which had held him all his life, was now combined with a problem that was professionally acceptable.

For seven years Wiles worked in isolation pursuing the proof. He described the experience as of doing mathematics in terms of a journey through a dark unexplored mansion. He says “You enter the first room of the mansion and it's completely dark. You stumble around bumping into the furniture, but gradually you learn where each piece of furniture is. Finally, after six months or so, you find the light switch, you turn it on, and suddenly it's all illuminated. You can see exactly where you were. Then you move into the next room and spend another six months in the dark. So each of these breakthroughs, while sometimes they're momentary, sometimes over a period of a day or two, they are the culmination of—and couldn't exist without—the many months of stumbling around in the dark that proceed them.”

In 1993, Wiles made the crucial breakthrough. The New York Times exclaimed "At Last Shout of 'Eureka!' in Age-Old Math Mystery," but unknown to them, and to Wiles, there was an error in the proof.  Wiles described the error to be in a crucial part of the argument, but it was something so subtle that he’d missed it completely until that point. The error is so abstract that it can't really be described in simple terms. Even explaining it to a mathematician would require the mathematician to spend two or three months studying that part of the manuscript in great detail.

After a year of work and after inviting the Cambridge mathematician Richard Taylor to work with him they repaired the proof. Below is a copy of the proof from the Annals of Mathematics, Modular elliptic curves and Fermat’s Last Theorem142 (1995), 443-551 [a hundred page proof]. Also, I have provided the Taylor and Wiles “repair”, Ring-theoretic properties of certain Hecke algebras, Annals of Mathematics, 141 (1995), 553-572.

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