'Comeback' stories of Mathematicians

Question

Do you know any mathematicians who has a 'comeback' story? I mean s/he starts working as a mathematician then somehow quits it, choses a different occupation, and then finally returns doing mathematics.

It is said that Yitang Zhang has worked at a motel and maden sandwiches at Subway and in 2013, he published a paper which proves that there are infinitely many prime pair which differs by at most $70$ millions. This may be the biggest comeback story I have ever read. I would like to know other stories if you know any.

P.s. I think that this subject is not subjective since the impact that is made by mathematicians are appreciated by many other mathematicians even if their research areas are not the same.

Answer 1

One fairly well-known example is Blaise Pascal who, following a vision in 1654, gave up scientific inquiry to devote himself to theology. Later in 1658, when he was unable to sleep due to a toothache, he undertook a significant investigation of the geometry of the cycloid that helped to distract him from the pain. The toothache subsided shortly thereafter, and Pascal went on to complete his study before once again abandoning mathematics. This can be regarded as a brief but historically noteworthy "comeback".

Answer 2

The Mathematics Apocrypha contains a story about a mathematician who becomes a criminal, eventually gets arrested for murder, and returns to mathematics in the jail cell.

Answer 3

On the internet, I came across with a video that tells the story of young Lev Pontryagin. I have heard him before but I did not know that he lost his eyes because of an explosion when he was 14. After the accident, he was able to continue his way to academia with his mothers tremendous help, which includes reading, writing and correcting scientific papers.

Pontryagin attended the town school where the standard of education was well below that of the better schools but the family's poor circumstances put these well out of reach financially. At the age of 14 years Pontryagin suffered an accident and an explosion left him blind. This might have meant an end to his education and career but his mother had other ideas and devoted herself to help him succeed despite the almost impossible difficulties of being blind. The help that she gave Pontryagin is described in 1 and 2:-

From this moment Tat'yana Andreevna assumed complete responsibility for ministering to the needs of her son in all aspects of his life. In spite of the great difficulties with which she had to contend, she was so successful in her self-appointed task that she truly deserves the gratitude ... of science throughout the world. For many years she worked, in effect, as Pontryagin's secretary, reading scientific works aloud to him, writing in the formulas in his manuscripts, correcting his work and so on. In order to do this she had, in particular, to learn to read foreign languages. Tat'yana Andreevna helped Pontryagin in all other respects, seeing to his needs and taking very great care of him.

It is not unreasonable to pause for a moment and think about how Tat'yana Andreevna, with no mathematical training or knowledge, made by her determination and extreme efforts a major contribution to mathematics by allowing Pontryagin to become a mathematician against all the odds. There must be many other non-mathematicians, perhaps many of whom are unrecorded by history, who have also by their unselfish acts allowed mathematics to flourish. As we try to show in this archive, the development of mathematics depends on a wide number of influences other than the talents of the mathematicians themselves: political influences, economic influences, social influences, and the acts of non-mathematicians like Tat'yana Andreevna.

But how does one read a mathematics paper without knowing any mathematics? Of course it is full of mysterious symbols and Tat'yana Andreevna, not knowing their mathematical meaning or name, could only describe them by their appearance. For example an intersection sign became a 'tails down' while a union symbol became a 'tails up'. If she read 'A tails right B' then Pontryagin knew that A was a subset of B!

Pontryagin entered the University of Moscow in 1925 and it quickly became apparent to his lecturers that he was an exceptional student. Of course that a blind student who could not make notes yet was able to remember the most complicated manipulations with symbols was in itself truly remarkable. Even more remarkable was the fact that Pontryagin could 'see' (if you will excuse the bad pun) far more clearly than any of his fellow students the depth of meaning in the topics presented to him. Of the advanced courses he took, Pontryagin felt less happy with Khinchin's analysis course but he took a special liking to Aleksandrov's courses. Pontryagin was strongly influenced by Aleksandrov and the direction of Aleksandrov's research was to determine the area of Pontryagin's work for many years. However this was as much to do with Aleksandrov himself as with his mathematics (1 and 2):

You can read the rest here.

1. P S Aleksandrov, V G Boltyanskii, R V Gamkrelidze and E F Mishchenko, Lev Semenovich Pontryagin (on his sixtieth birthday) (Russian), Uspekhi Mat. Nauk 23 (6) (1968), 187-196.

2. P S Aleksandrov, V G Boltyanskii, R V Gamkrelidze and E F Mishchenko, Lev Semenovich Pontryagin (on his sixtieth birthday), Russian Math. Surveys 23 (6) (1968), 143-152.

   His biography on Wiki.