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发帖数: 31659 | 1 【 以下文字转载自 EE 讨论区 】
发信人: guvest (我爱你老婆Anna), 信区: EE
标 题: NYT: Solving a Riddle of Primes
发信站: BBS 未名空间站 (Mon May 20 22:48:57 2013, 美东)
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发信人: dionysus (悲剧的诞生), 信区: Mathematics
标 题: NYT: Solving a Riddle of Primes
发信站: BBS 未名空间站 (Mon May 20 21:27:36 2013, 美东)
http://www.nytimes.com/2013/05/21/science/solving-a-riddle-of-p
Solving a Riddle of Primes
By KENNETH CHANG
Published: May 20, 2013
Three and five are prime numbers — that is, they are divisible only by 1
and by themselves. So are 5 and 7. And 11 and 13. And for each of these
pairs of prime numbers, the difference is 2.
Mathematicians have long believed that there are an infinite number of such
pairs, called twin primes, meaning that there will always be a larger pair
than the largest one found. This supposition, the so-called Twin Prime
Conjecture, is not necessarily obvious. As numbers get larger, prime numbers
become sparser among vast expanses of divisible numbers. Yet still —
occasionally, rarely — two consecutive odd numbers will both be prime, the
conjecture asserts.
The proof has been elusive.
But last month, a paper from a little-known mathematician arrived “out of
the blue” at the journal Annals of Mathematics, said Peter Sarnak, a
professor of mathematics at Princeton University and the Institute for
Advanced Study and a former editor at the journal, which plans to publish it
. The paper, by Yitang Zhang of the University of New Hampshire, does not
prove that there are an infinite number of twin primes, but it does show an
infinite number of prime pairs whose separation is less than a finite upper
limit — 70 million, for now. (Dr. Zhang used 70 million in his proof —
basically an arbitrary large number where his equations work.)
“It’s a deep insight,” Dr. Sarnak said. “It’s a deep result.”
Dr. Zhang said he had been working on the Twin Prime Conjecture for years
and, like everyone else, failed. “I tried everything,” he said.
Then, last July, “just very suddenly, an idea came to my mind,” Dr. Zhang
said. “I was confident in this way I could prove it.”
It took him another six months to fill in the details, but he appears to be
right. The paper has been accepted pending some small revisions. “It’s
remarkable the speed this paper was dealt with,” Dr. Sarnak said.
Dr. Zhang’s proof takes advantage of a 2005 paper by Daniel Goldston of San
Jose State University, Janos Pintz of the Alfred Renyi Institute of
Mathematics in Budapest and Cem Yildirim of Bogazici University in Istanbul,
which had shown there would always be pairs of primes closer than the
average distance between two primes.
Still, in mathematics, closer does not necessarily mean two numbers away,
and experts were unable to make further progress on the conjecture. “People
tried, and after a few years, it seemed this was really far away,” Dr.
Sarnak said.
Dr. Zhang also used techniques developed in the 1980s by Henryk Iwaniec of
Rutgers, Enrico Bombieri of the Institute for Advanced Study and John B.
Friedlander of the University of Toronto, adding his own ingenuity to tie
everything together in a way others had been unable to.
“He got it,” said Dr. Iwaniec, who has read Dr. Zhang’s paper. “There’s
no question about it.”
The next step is reducing that 70 million separation, and Dr. Zhang said “
that should be very simple.” But experts like Dr. Iwaniec said bringing it
all the way down to 2 — the full Twin Prime Conjecture — would probably
require more mathematical breakthroughs. |
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