**Christian Goldbach** was a Prussian mathematician best known for the conjecture he made in a letter to Euler that every even integer > 2 is a sum of two primes.

- Goldbach was brought up in Königsberg and attended the university there.
- In Leipzig in 1711 he met Leibniz and after Goldbach moved on the two carried on a correspondence.
- Goldbach met him and also de Moivre in London, and he met Nicolaus (I) Bernoulli again in Oxford.
- Goldbach was fascinated by mathematics but he did not have much knowledge of the subject.
- When Bernoulli started to discuss infinite series with Goldbach as they talked in Oxford, Goldbach confessed that he knew nothing about the topic.
- Goldbach continued his lengthy tour and was in Venice in 1721.
- By 1724 Goldbach was back in his home town of Königsberg and there he met two people who would change his life, namely Georg Bernhard Bilfinger and Jakob Hermann.
- The charge arose through his association with the philosopher Christian Wolff, who had then helped arrange that Bilfinger should be involved in setting up the Imperial Academy of Sciences (later called the St Petersburg Academy of Sciences) which was to be organised (at Leibniz's suggestion) along the lines of the Berlin Academy of Sciences.
- He was on his way to St Petersburg when he met Goldbach, and Jakob Hermann was also on his way to take part of this new exciting venture.
- When he was in Riga in July 1725, Goldbach wrote to L L Blumentrost, the President elect of the proposed new Academy, asking for a position there.
- After an initial rejection, Goldbach was offered the positions of professor of mathematics and historian at St Petersburg.
- One may wonder how Goldbach was offered such an important position.
- We mentioned that Goldbach gave up his attempts to understand infinite series in 1712.
- Goldbach published Specimen methodi ad summas serierum Ⓣ(Examples of methods of summing series) in Acta eruditorum in 1720.
- Goldbach was recording secretary for the opening ceremony of the Academy which was held on 27 December 1725, and continued to act in this role until January 1728.
- Goldbach was appointed to the position and he moved to Moscow when Peter moved the court there in January 1728.
- Euler had arrived in St Petersburg on 17 May 1727 and after Goldbach moved to Moscow he began a correspondence with Euler in 1729.
- Goldbach was no longer required as a tutor, but he continued to serve Anna.
- In 1732 Anna moved the court back to St Petersburg and Goldbach returned there and again became active in the Academy as well as being heavily involved with the Russian government.
- Goldbach's problem, however, was that as well as being heavily involved with the administration of the Academy, he was also rising to more responsible roles in the government of Russia.
- Goldbach, however, seemed able to continue to hold positions of high influence despite the changes at the top.
- Goldbach's polished manners and cosmopolitan circle of friends and acquaintances assured his success in an elite society struggling to emulate its western neighbours.
- In 1740 Goldbach requested that his duties at the Academy be reduced, and when he was appointed to a senior position in the Ministry of Foreign Affairs, he ceased all his work for the Academy.
- The guidelines Goldbach drew up became the accepted practice for the next 100 years.
- Goldbach did important work in number theory, much of it in correspondence with Euler.
- Goldbach also conjectured that every odd number is the sum of three primes.
- The last conjecture was made by Goldbach in a letter written to Euler on 18 November 1752.
- Euler replied on 16 December, saying he had checked Goldbach's conjecture up to 1000.
- In a letter of 3 April 1753, Euler reported to Goldbach that he had checked it up to 2500.
- No other examples of numbers failing to satisfy this conjecture of Goldbach seem to be known.
- It is interesting to ponder that Goldbach could, with some hard work, have tested this conjecture to 2500 as Euler did.
- Although Goldbach published a number of works other than the ones we have mentioned above, it is the insight which he showed in his letters which have proved by far his most important mathematical contribution.

Born 18 March 1690, Königsberg, Brandenburg-Prussia (now Kaliningrad, Russia). Died 20 November 1764, Moscow, Russia.

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Algebra, Analysis, Origin Russia, Number Theory, Special Numbers And Numerals, Topology

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive