Fermat's Last Theorem
Fermat's last theorem (also called Fermat's Great Theorem) states that there are no positive natural numbers a, b, and c such that
- an + bn = cn
in which n is a natural number greater than 2. About this the 17th-century mathematician Pierre de Fermat wrote in 1637 in his copy of Claude-Gaspar Bachet's translation of Diophantus' Arithmetica, "I have discovered a truly remarkable proof but this margin is too small to contain it". The reason why this statement is so significant is that all the other theorems proposed by Fermat were settled either by proofs he supplied, or by more rigorous proofs supplied afterwards. Mathematicians long were baffled by this statement, for they were unable either to prove or to disprove it. The theorem has the credit of most number of wrong proofs!
For various special exponents n, the theorem had been proved over the years, but the general case remained illusive. In 1983 Gerd Faltings proved the Mordell conjecture, which implied that for any n>2, there are at most finitely many coprime integers a, b and c with an + bn = cn.
Using sophisticated tools from algebraic geometry (in particular elliptic curves and modular forms), Galois theory and Hecke algebras, the English mathematician Andrew Wiles, with help from his former student Richard Taylor, devised a proof of Fermat's Last Theorem that was published in 1995 in the journal Annals of Mathematics.
Frey had conjectured ("Epsilon conjecture"), and Ribet had proved in 1986, that every counterexample an + bn = cn to Fermat's last theorem would yield an elliptic curve
- y2 = x (x - an) (x + bn)
which would provide a counterexample to the Taniyama-Shimura Conjecture. This latter conjecture proposes a deep connection between elliptic curves and modular forms. Wiles and Taylor were able to establish a special case of the Taniyama-Shimura Conjecture sufficient to exclude such counterexamples arising from Fermat's last theorem.
The story of the proof is almost as remarkable as the mystery of the theorem itself. Wiles spent 7 years in isolation working out nearly all the details. When he presented his proof in June 1993, he blew away his audience with the number of ideas and constructions used in his proof. Unfortunately, upon closer inspection a serious problem was discovered which seemed to break his original proof. Wiles and Taylor then spent about a year trying to repair the proof. In September 1994, they were able to resurrected the proof with some techniques Wiles had used in his earlier work and apparently created an even more elegant proof as a result.
There is some doubt over whether the "..truly remarkable proof .." of Fermat's was correct. The methods used by Wiles were unknown when Fermat was writing, and it seems unlikely that Fermat managed to derive all the necessary mathematics to demonstrate the same solution (in the words of Andrew Wiles, "its impossible, this is a 20th century proof"). The alternatives are that there is a simpler proof that all other mathematicians up until this point have missed, or that Fermat was mistaken.
See also:
External links and References:
- Andrew Wiles: Modular elliptic curves and Fermat's Last Theorem, Annals of Mathematics 141 (1995), pp. 443-551.
- R.Taylor and A.Wiles: Ring theoretic properties of certain Hecke algebras, Annals of Mathematics 141 (1995), pp. 553-572, online at http://abel.math.harvard.edu/~rtaylor/
- Gerd Faltings: The Proof of Fermat's Last Theorem by R. Taylor and A. Wiles, Notices of the AMS July 1995, http://www.ams.org/notices/199507/faltings.pdf
- Charles Daney: The Mathematics of Fermat's Last Theorem, http://cgd.best.vwh.net/home/flt/flt01.htm
- J J O'Connor and E F Robertson: Fermat's last theorem, http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Fermat's_last_theorem.html. The history of the problem.
- BBC transcript: Fermat's last theorem, http://www.bbc.co.uk/science/horizon/fermat.shtml. Wiles describes the moment of revelation in a transcribed interview.