# Twin prime conjecture

The**twin prime conjecture**is a famous problem in number theory that involves prime numbers. It states:

There are an infinite number of primespsuch thatp+ 2 is also prime.

Such a pair of prime numbers is called a twin prime. The conjecture has been researched by many number theorists. Mathematicians believe the conjecture to be true, based only on numerical evidence and heuristic reasoning involving the probabilistic distribution of primes.

In 1849 de Polignac made the more general conjecture that for every natural number *k*, there are infinitely many prime pairs which have a distance of 2*k*. The case *k* = 1 is the twin prime conjecture.

Table of contents |

2 Hardy-Littlewood conjecture 3 Serious problem found in potential proof 4 See also 5 External links |

### Partial results

In 1940, Erdös; showed that there is a constant *c* < 1 and infinitely many primes *p* such that *p*' − *p* < *c* ln *p*, where *p*' denotes the next prime after *p*. This result was successively improved; in 1986 Maier showed that a constant *c* < 0.25 can be used.

In 1966, Chen Jingrun showed that there are infinitely many primes *p* such that *p* + 2 is either a prime or a semiprime (i.e., the product of two primes). The approach he took involved a topic called sieve theory, and he managed to treat the twin prime conjecture and Goldbach's conjecture in similar manners.

### Hardy-Littlewood conjecture

There is also a generalization of the twin prime conjecture, known as the **Hardy-Littlewood conjecture** (after G. H. Hardy and John Littlewood), which is concerned with the distribution of twin primes, in analogy to the prime number theorem. Let π_{2}(*x*) denote the number of primes *p* ≤ *x* such that *p* + 2 is also prime. Define the **twin prime constant** *C*_{2} as

*p*≥ 3). Then the conjecture is that

in the sense that the quotient of the two expressions tends to 1 as *x* approaches infinity.

This conjecture can be justified (but not proven) by assuming that 1 / ln *t* describes the density function of the prime distribution, an assumption suggested by the prime number theorem. The numerical evidence behind the Hardy-Littlewood conjecture is quite impressive.

### Serious problem found in potential proof

On May 26, 2004, Richard Arenstorf of Vanderbilt University submitted a 38-page proof that there are, in fact, infinitely many twin primes. On June 3, Michel Balazard of University Bordeaux reported that Lemma 8 on page 35 is false.[1] As is typical in mathematical proofs, the defect may be correctable or a substitute method may repair or replace the defect. Arenstorf withdrew his proof on June 8, noting "A serious error has been found in the paper, specifically, Lemma 8 is incorrect".

## See also

## External links

There Are Infinitely Many Prime Twins'' - R. Arenstorf Withdrawn June 8, 2004.