Alan Turing was an amazing scientist who became known as the father of the modern computer. He helped break the Enigma code during World War II and developed the Turing Machine. His work during the war saved numerous lives and shortened the length of the war. He took his own life in 1954.

### Early Years

Alan Turning was born on June 23, 1912 in England (although he was conceived in India). His father worked in the Indian civil service and as a result, Turing’s parents spent a lot of time in India. They didn’t bring Alan or his brother, John, with them because they were concerned that the children would become ill in India. While they were gone, the two boys lived with family friends in England. Even at a young age, Turing showed a lot of interest in math and science. In fact, his mother was very concerned about Turing’s interest in science because she felt that this would stop him from getting into a good English public school.

When he was fourteen years old, he went to theSherborne School in Dorset. Turing was excited about going to the school and he was so determined to get there that when a transportation strike got in the way of going to school, Turing rode his bicycle almost one hundred kilometers to the school.

The Sherborne School was a famous public school that was focused more on the classics than on science and math. This was to cause Turing a bit of trouble with his teachers since Turing was so interested in studying science and math.

The headmaster of the school even wrote to Turing’s parents expressing his concern with Turing’s focus on math and science.

While at school, Turing discovered Einstein’s work of relativity. Turing’s private notes show that even though he was only sixteen years old, he had a good understanding of the theory.

Turing was obviously a gifted student but his school did not want him to take the School Certificate test for fear that his poor performance would embarrass the school.

Turing began to do better at school after he met Christopher Morcom, a fellow student who was to become Turing’s good friend. Unfortunately, Morcom died of as a result of contracting bovine tuberculosis during their last year at Sherborne.

After graduating from Sherborne, Turing applied for a scholarship to Trinity College in Cambridge. He did not win the scholarship because of his unwillingness to pursue his classical studies.

He only wanted to focus on math and science. As a result, he ended up in King’s College in 1931 and graduated in 1934. His dissertation was on the Gaussian error function for which he became a fellow of King’s College.

### The Turing Machine

In 1936, Turing published a paper titled “On Computable Numbers, with an Application to the Entscheidungs problem.”This was the paper that set out the concept of what became known as the Turing machine.

The Entscheidungs problem was the problem of whether there was a way or method (an algorithm) to decide if a mathematical assertion could be proved.

To answer the question, Turing came up with the concept of a machine that would perform any mathematical function as long as it was an algorithm.

Turing thought of his machine as being made up of a head or scanner (able to write or erase marks) and a long tape (infinitely long).

The user would also have to have a specific set of instructions for the machine to follow. The tape would be divided into squares and the scanner would read each square.

It would then perform a specific action depending on the finite instructions that the machine user had written. The machine could write or erase a symbol, move the tape one block left or right, move on to the next instruction, or stop.

Turing used this concept to show that it was impossible to use an algorithm to tell if the machine would ever stop.

In order for a mathematical assertion to be proven, the machine would have to stop. Since you couldn’t tell if the machine would stop, it was impossible to know if a mathematical assertion could be proved.

Even though Turing had solved the Entscheidungsproblem, it was actually solved a few months before he published by a logician named Alonzo Church.

Even though Church solved the problem first, Turing’s approach was original and different. Turing relied on operations that could be done while Church relied on mathematical assumptions.

The Turing machine has become the basis for modern computation and computability theory.

Turing spent the next two years (1937 and 1938) at Princeton University where he obtained his PhD. He studied under Alonzo Church while at Princeton. During his time at Princeton, Turing studied number theory and algebra.

He also worked on a cipher machine. When Turing returned to England, he began secretly working part time at the Government Code and Cypher School, the British organization responsible for breaking codes. When World War II started, Turing began workingfull timeat Bletchley Park as a code breaker for the British government.

### World War II

Turing began working in Bletchley Park (in what was called Hut 8) where he was concerned with breaking German codes. He helped devise a machine, called the bombe, to help break the German Enigma code.

The bombe was based on the work done by Polish mathematicians, who had created a machine called the bomba. The Polish mathematicians had been working on cracking the Enigma code much earlier than England.

The Polish approach relied on the specific way that Germans used the Enigma machine and as a result, was limited in its use. Turing used the Polish machine as a basis for developing a much more powerful machine that could break any German code as long as a small portion of the text could be guessed.

With the help of another mathematician, Gordon Welchman, Turing was able to develop a machine to read the Enigma code.

The machine (the bombe) searched for the correct setting of the Engima machine (a set of rotors). In order to do this, the code breakers needed to guess what a small part of the encoded message said. This was called the crib.

It was difficult to find a crib. In order to guess at a piece of the code, the code breakers needed to know German military phrases as well as how specific operators communicated. They could use this knowledge to guess at what a particular piece of text might say.

This information would then be set into the bombe. The bombe would use this information to check each possible setting for the rotors in the Enigma machine.

These settings were changed every day so Turing and the rest of the codebreakers needed to break a new code every day.

Once a possible setting was found, the bombe would conduct a number of deductions based on the crib. If a contradiction was found, then the machine would move to the next setting.

A majority of the possible settings would cause these contradictions and only a few possible settings would be left. The few settings left would be analyzed in greater detail to see if they broke the German code for the day.

The first bombe machine was set up on March 18, 1940 and over two hundred of the machines were in use by the end of the war.

After helping break the Enigma code, Turing turned his attention to the Naval Enigma code. This is the code that was used by the German Navy and was much more complex.

Turing has stated that part of the reason he took on breaking the Naval Enigma was that no one else was working on it so he could have the problem to himself.

The first step to breaking the Naval Enigma code was to determine the indicators. The indicator is the message key which the person sending the encrypted message would send to the person receiving the message.

This message key (or indicator) would tell the person receiving the message how to set up the Enigma machine so that the message could be read.

In the end of 1940, Turing figured out the indicator system used by the German Navy and on the same day, he came up the analytical process Turing called Banburismus.

Banburismus was a technique using statistics that could eliminate a number of the possible Enigma rotor settings. This would allow the codebreakers to break the code much quicker.

In the spring of the following year, Turing asked Joan Clarke to marry him (even though he was gay). Turing admitted he was gay to Clarke but apparently she did not care about that. Turing decided he couldn’t go through with the marriage and broke off the engagement in the summer of 1941.

In the middle of 1942, Turing developed another codebreaking technique to be use against another German code. This code was called the Lorenz cipher. Turing came up with a technique which was called Turingery.

Turingery was a paper and pen process which required the codebreaker to calculate what is known as a delta for adjacent letters. This breakthrough was very important for the decoding of the Lorenz cipher.

In November 1942, Turing went to the United States to help work on the American construction of a bombe although he was not that impressed with the American designs or the way they attempted to break the German codes.

Turing returned to England in early 1943 where he became a general consultant in Bletchley Park since Hugh Alexander had become the new head of Hut 8.

This was the position that Turing had previously held, but he had little interest in running the section and Alexander had been basically running the section anyway. Turing was more interested in the actual work rather than ensuring the smooth running of the department.

Turing developed an interest in electronics. He taught himself the basics and then began to design a portable machine that could be used for secure voice communications. The machine, codenamed Delilah, was completed too late to be used in the war.

When completed, Turing demonstrated the machine by encrypting and then decrypting a speech given by Winston Churchill. The military decided not to use the device.

After the war, Turing was awarded the Order of the British Empire for his work on codes although the actual work he did remained top secret for some time.

### After the War

After the war, Turing went back to thinking about computers and how they worked. He changed his mind about whether the human brain did things that were incapable of being computed.

He felt that it was possible to develop a computer that could show intelligence.While Turing was working at the National Physical Laboratory, a researcher by the name of Von Neumann published a paper outlining the design for an electronic computer. Once again, someone had published before Turing.

Although Von Neumann published his work before Turing, Von Neumann’s work spurred the place where Turing worked (National Physical Laboratory) to push for the development of its own electronic computer.

Turing was made the Senior Principal Scientific Officer for this project. Turing began to work on the design for an electronic computer which would be called the Automatic Computing Engine (ACE).

Turing’s recognized that any hardware design for a computer would only be used for a short time given the changes in technology. As a result, Turing focused on the concepts behind a universal machine.

A universal machine would work through programming and not on the electrical components.Turing described a computer that could switch from a variety of tasks such as file handling, algebra, or playing chess.

He also showed how to handle subroutines in a computer so that the machine could expand its own computer programs.

Unfortunately, Turing was frustrated over the lack of progress on his machine and the ACE was never constructed. Other projects to build a computer that were being run at Cambridge and Manchester moved ahead of Turing’s plan.

Turing went to Cambridge on a leave from the National Physical Laboratory and while he was gone, the ACE was built. It ran its first program on May 10, 1950.

### Turing the Runner

Turing had always enjoyed running. He stated that it helped to clear his mind. He began to train and run competitively in long distance runs. He would even run more than fifteen kilometers to meetings, often beating this colleagues who were taking public transportation.

He ran in amateur races and won a number of them. In fact, he might have been considered for the 1948 Olympic team if he hadn’t suffered an injury. His best marathon time that year was only eleven minutes slower than the winner of the gold medal.

In 1948, he left his job at the National Physical Laboratory to take a new job at Manchester University. He became the Deputy Director of the computing laboratory.

To some extent, Turing seemed a bit lost here and never worked up to his potential. He spent his time looking at both old and new topics but never really focused on one area.

Even though he did not make any major breakthroughs at this time, he did publish a paper that spelled out his approach to artificial intelligence. The paper set out the details for what became known as the Turing Test.

### The Turing Test

Turing had become involved in the debate as to whether artificial intelligence was possible (i.e., could a machine think like a human brain).

Turing believed that it was possible and set up a test to determine what was required for a computer to be called aware. Turing felt that if a machine acted as if it had the ability to think, then it did have the ability.

Turing developed a simple test that was designed to test this. A person would be sitting in one room while another person and a computer would be placed in two other rooms. The person in the first room would ask questions to both the other person and the computer.

The person asking the questions must evaluate the answers given by both and determine which one, if any, is a computer. If the person cannot tell which one is human and which one is a computer, then the computer is deemed to be intelligent.

The Turing Test is still used today in discussions over artificial intelligence. In Turing’s paper, he addressed a number of objections to the idea of computers having intelligence. In fact, the paper covered almost all of the objections over artificial intelligence that have been raised to date.

### Scandal

Things began to go seriously wrong for Turing in 1952. An acquaintance, Arnold Murray, and an accomplice broke into Turing’s house and robbed him. When Turing went to the police to report the crime, he admitted that he knew Arnold Murray and, in fact, had a sexual relationship with the man.

In the 1950s, homosexuality was a crime in England and as a result of his admission, Turing was charged with gross indecency. Turing went on trial on March 31, 1952, and instead of denying the charges, he admitted to it all.

He did not try to mount a defence and instead told the court that he saw nothing wrong with his actions. Turing was convicted and given a choice: he could go to jail or submit to chemical castration.

Chemical castration is the use of drugs to get rid of a person’s sex drive. Turing did not want to go to jail so he agreed to the treatment.

Over the course of a year Turing received oestrogen (a hormone that causes the body to develop female characteristics) shots which not only shut down his sex drive but also had a number of other side effects, including causing Turing to develop breasts.

During this time, Turing had secretly been working part time with the General Command Headquarters (GCHQ) on cryptography.

At the time, known homosexuals were not allowed to have a security clearance.As a result, Turing lost his security clearance and he was no longer allowed to work for the GCHQ.

Turing was not able to talk to many people about what he was going through, particularly about the loss of his security clearance. He put on a brave face to the world around him but in the end, he couldn’t cope.

Turing died on June 7, 1954 and the body was found the next day by the person who came to clean his house. A half-eaten apple was found next to his body.

An autopsy concluded that Turing had died from cyanide poisoning. Even though a half-eaten apple was found next to his body, the apple was never tested for cyanide.

Turing’s death was ruled a suicide, but there have been claims that it was an accidental death and even claims that he was murdered. Turing’s mother believed that Turing ate the cyanide accidentally from his fingers after performing a chemistry experiment.

An expert on Turing’s life, Jack Copeland, also argued that Turing’s death might have been accidental in an article published by the BBC in 2012. Copeland claimed that Turing did not appear suicidal and he conducted chemical experiments in his house with cyanide.

It has even been suggested that Turing was murdered because he was perceived as a security risk given that he was gay, but there is little evidence to support this view.

### Awards and a Pardon

Turing received the Order of the British Empire at the end of World War II but after that, he did not receive a lot of recognition from the public, even after his death.

That all changed forty years later. In 1999, he was named one of the most important people in the 20^{th} century by Time magazine. In a 2002 BBC poll, Turing was twenty-first on the list of 100 Greatest Britons.

Two statues of Turing have also been put up—one at the University of Surrey and one at Bletchley Park. In 2009, Gordon Brown, the British prime minister at the time, issued an apology to Turing for the government’s prosecution of him as a homosexual.

In 2013, Turing was officially pardoned by Queen Elizabeth II although there was some controversy over the pardon because Turing was convicted under the law at that time, regardless of what people think of the law now.

A pardon is typically given to a person who is innocent or at the request of a person such as a family member but this did not happen in this case.

It has been claimed that Turing’s work in Bletchley Park ended the war two years earlier and as a result, saved a number of lives. He is also viewed as a pioneer in the field of computers and artificial intelligence.