The 20th century was rich in tech innovations, revolutionary ideas, and scientific concepts that significantly changed people’s lives. Many of the technologies we use today, such as computers, the Internet, printers, the World Wide Web (WWW), and even the first artificial intelligence (AI) computer, were created in the previous century thanks to many great scientists.

Alan Turing was and still is one of the greatest mathematicians and computer scientists of the 20th century, often considered the father of computer science. Hence, in this article, we talk about the life of Alan Turing and his mathematical and technical discoveries.

If you are looking for more information on modern technology, check out these AITJ articles: 5 Ways AI can Improve Environmental Sustainability and The Law of Accelerating Returns, Superintelligence, and The Technological Singularity.

## The Contributions of Alan Turing

Born in 1912 in London, Alan Mathison Turing was a professional in many scientific spheres, including **theoretical biology, mathematics, computer science, philosophy, and cryptanalysis**.

During his university studies from 1931 to 1934 at King’s College, Alan Turing showed great interest in mathematics. In 1935, the young mathematician was elected a Fellow of King’s College because his dissertation, which proved the central limit theorem, was noticed by the university committee.

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One year later, in 1936, in his paper, *On Computable Numbers, with an Application to the Entscheidungsproblem*, Turing introduced the concept of simple hypothetical devices that later became well-known as **Turing machines**. John von Neumann (a Hungarian-American mathematician) stated that the core concept of modern computers was developed based on Turing’s paper. Even nowadays, Turing machines are one of the primary research fields in the theory of computation.

Not only is Alan Turing well-known for the introduction of the aforementioned concept, but Turing was also one of the leading participants in the decryption of German coded messages during World War II. In December 1939, the mathematician **solved the essential part of the naval indicator system** of Nazi’s Enigma and several years later contributed as a consultant for cryptanalysis.

Some of his war-time papers, titled *The Applications of Probability to Cryptography* and *Paper on Statistics of Repetitions,* were of such importance to the British government that they weren’t released to the UK National Archives even after the end of the Second World War. These papers were brought to the public eye only in 2012, nearly 50 years after Alan Turing’s death.

## Turing’s Personal Life

Alan Turing developed many innovative concepts during his lifetime, and one article wouldn’t be enough to explain all of them. That’s why I’ll focus on one of the computer science concepts he is most recognized for – the Turing Machine. However, before I do so, I want to briefly cover Turing’s personal life, which is sometimes believed to lead to Turing’s death.

In January 1939, a 39-years-old Turing started a relationship with Arnold Murray – a man he accidentally met on the street and invited for lunch. Several days later, Alan had his house burgled, and Murray admitted his acquaintance with the burglar. Once Turing reported the burglary to the police and admitted his homosexual relationships (which were considered a criminal offense at that time), the mathematician was brought to trial in 1952 and given a choice between probation and imprisonment. Turing chose the first option, which led to his death two years later.

The probation option prescribed the mathematician to undergo hormonal physical changes, referred to as “chemical castration.” This procedure aimed to reduce sexual activity and make a person impotent. Turing faced all of these side effects along with unclear thinking and the formation of breast tissue. Moreover, Alan Turing was denied entry into the USA and barred from continuing his participation in cryptographic consultancy.

The mathematician died in 1954 due to cyanide poisoning (Turing ate an apple poisoned with cyanide). Some believe this was a suicide as Turing’s favorite story was about Snow-white, who was poisoned through an apple by her stepmother. Alan Turing’s early death is a tragic event as we can only imagine how many other revolutionary concepts and papers the mathematician could create were it not for UK’s discriminating policy and barbaric chemical castrations at that time.

## Turing Machine

The first personal computer was invented in 1981 – 30 years after Turing’s death. No computers meant that every mathematical calculation was performed by trained professionals manually. Now imagine that in a time when there were no computers, Turing managed to develop a concept that is still relevant today.

The concept of a Turing Machine (TM) presents a mathematical model that describes a machine capable of performing any calculation given an unlimited amount of paper, pencil, and eraser. Hence, a TM consists of

- An infinite-length tape divided into cells on which specific symbols (or the input) are given;
- A head that can read and write down the needed input symbols (the head is always over one cell of the tape)

Every operation conducted by a Turing Machine ends with a change in a cell’s internal state. For instance, the machine reads an input symbol, replaces it with another (and, in this way, changes the cell’s state), and moves from the cell to the left or right.

In a nutshell, we reviewed the life, education, and many inventions of Alan Turing, as well as explained one of his most well-known mathematical concepts. In addition, we covered Turing’s personal life and mentioned some of his papers.

Hanna is a first-year student at the University of Nicolaus Copernicus, Torun. After leaving her previous university in Belarus, she moved to Poland to study Cognitive Science and its application in Marketing. She is deeply interested in modern technologies, specifically AI and Metaverse, and their influence on society.