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# Who is Alan Turing?

Alan Turing (1912 - 1954) was a British mathematician, logician, and cryptographer considered by many to be the father of computer science. His contributions to breaking the German Nazi Enigma code during WWII were considered pivotal to the Allied war effort. Alan Turing formulated multiple ideas that now lie at the foundations of computer science and computability theory, such as the idea of a *Turing machine* or the *Church-Turing thesis*.

A Turing machine is a simple mathematical construct that can be imagined as a recordable tape of infinite length coupled to a mechanical unit with read/write capability. The unit can perform only three actions; read a bit of the tape and return the result; write a bit on the tape; or erase a preexisting bit. Turing's Church-Turing thesis, formulated with Alonzo Church, states that such a Turing machine can theoretically compute any algorithm given enough time and storage space. It also states that any practical computing model must be a type of Turing machine. By extension, this means that the human brain can be defined as a Turing machine, because it processes information in the only way that information can be processed; by reading, writing, and manipulating bits of memory.

The Church-Turing thesis also claims that any algorithm can be run on anything that qualifies as a Turing machine. Turing helped formulate the original definition of an algorithm, which is roughly as follows: 1) an algorithm will consist of a finite set of precise instructions to be executed; 2) be computable in a finite number of steps (the inability of a program to determine whether or not it can be executed in a finite number of steps is called "the halting problem"); 3) be computable in principle with only a pen, paper, and infinite time; 4) require no background information to execute, that is, be self-contained.

Alan Turing was educated at Cambridge and Princeton throughout the 30s. In 1936, Turing published a very influential paper, *On computable numbers, with an application to the Entscheidungsproblem*, answering an open question posed by Kurt Goedel in 1931, which showed that there is no algorithmic way to determine whether a given first-order statement in symbolic logic is universally valid. In 1938, Alan Turing earned his PhD from Princeton under Alonzo Church.

Alan Turing spent his post-war years working on some of the first reprogrammable digital computers, producing one of the first designs in 1946. He also addressed the problem of artificial intelligence, formulating the *Turing Test*, a test for determining whether or not a machine deserves to be called conscious and intelligent. In the Turing Test, a human being types words into a keyboard to communicate with two hidden persons, one an actual human being, the other an AI. If the human being cannot distinguish which communicant is the human and which is the AI, the AI is said to have passed the Turing Test. Some futurists, such as National Medal of Technology winner Ray Kurzweil, have suggested that we will have a Turing Test-passing computer before 2030.

Alan Turing died in 1954, due to a cyanide-laced apple. His death is said to be a suicide, a result of being prosecuted for homosexuality and being forced to take hormones by the government.

## Frequently Asked Questions

### Who was Alan Turing and why is he significant?

Alan Turing was a British mathematician, logician, cryptanalyst, and computer scientist who is widely considered to be the father of theoretical computer science and artificial intelligence. His work on breaking the Enigma code during World War II significantly contributed to the Allied victory by deciphering encrypted German messages. Turing's 1936 paper, "On Computable Numbers," laid the groundwork for the modern computer. His contributions to the field are so influential that the prestigious Turing Award, often referred to as the "Nobel Prize of Computing," is named in his honor.

### What was Alan Turing's role in World War II?

During World War II, Alan Turing played a pivotal role as a member of the Government Code and Cypher School at Bletchley Park, Britain's codebreaking center. He was instrumental in developing techniques to crack the German Enigma machine, which encrypted Nazi communications. Turing's work, particularly the creation of the Bombe machine, allowed the Allies to intercept and decode enemy messages, providing critical intelligence that hastened the end of the war.

### What is the Turing Test and its significance in artificial intelligence?

The Turing Test, proposed by Alan Turing in 1950, is a measure of a machine's ability to exhibit intelligent behavior equivalent to, or indistinguishable from, that of a human. In his seminal paper "Computing Machinery and Intelligence," Turing suggested that if a machine could engage in a conversation with a human without the human realizing they were talking to a machine, it could be considered "intelligent." The Turing Test has become a foundational concept in the philosophy of artificial intelligence and continues to influence debates about machine consciousness and capabilities.

### How did Alan Turing's work influence modern computing?

Alan Turing's theoretical contributions laid the foundation for modern computing. His concept of a "universal machine" that could perform any computable task formed the basis of the modern computer. Turing's ideas about algorithms and computation have influenced the development of programming languages and software engineering. His impact is so profound that the Association for Computing Machinery (ACM) established the Turing Award to recognize individuals for their contributions to the computing field, reflecting Turing's monumental legacy.

### What recognition has Alan Turing received posthumously?

Alan Turing has received numerous posthumous recognitions for his contributions to computing and wartime efforts. In 2013, Queen Elizabeth II granted him a royal pardon for his 1952 conviction for homosexual acts, which were then illegal in the UK. In 2019, the Bank of England announced that Turing would be featured on the new ¬£50 note, celebrating his scientific achievements. Additionally, various academic institutions, awards, and buildings have been named in his honor, ensuring his legacy endures.

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