New UK Fifty Pound Banknote Honors Computer Pioneer Alan Turing – CWI Amsterdam



Wednesday June 23, Bank of England launches new 50 pound polymer banknote starring mathematician, computer pioneer and code breaker Alan Turing (1912-1954). The banknote contains many geeky features of Turing’s pioneering work in math, computer science, decryption, and even mathematical biology. CWI researchers and professors Lynda Hardman and Jurgen Vinju comment on the significance of Turing’s work for computing and society today.

In 2019, Alan Turing was selected from a shortlist of British scientists to be featured on the new banknote. The June 23 release date was chosen because it is Turing’s birthday. CWI research professor Jurgen Vinju is delighted with Alan Turing’s post: “It highlights the fact that information technology in general and computers in particular are fundamental infrastructures for modern society. This honor goes to Turing who gave the field its theoretical foundations and the corresponding motivation to make digital computers a reality.

Turing’s work is still very relevant, Vinju says. “I just finished writing an academic article in which I refer to the Turing machine of 1936. In this article, I designed a new programming language. I was looking for the limits to calculate certain numbers, and the limits are defined by the Turing machine.

The Turing machine is actually a mathematical model: any problem that can be calculated can be calculated on a universal Turing machine. Our personal computers, laptops, tablets and smartphones are all simpler versions of a universal Turing machine. In 2012, during the celebration of Alan Turing’s 100th birthday, two members of the CWI group from Vinju, Jeroen van den Bos and Davy Landman, actually built a Lego Turing machine: The Lego Turing Machine demonstrates the most basic principles of any computer in a way that is attractive and simple to a wide audience.

Specimen of the Turing side of the new banknote. Credit: Bank of England.

Let’s take a closer look at the new banknote. As is traditionally the case, Queen Elizabeth appears on the front of the banknote. This is the reverse side which is entirely dedicated to Alan Turing and shows plenty of geeky illustrations of Turing’s pioneering work:

  • The most eye-catching is Alan Turing’s portrait, which is based on a photo taken in 1951, which is now part of the Photographic Collection of the National Portrait Gallery in London.
  • At the bottom right of the portrait, we see Turing’s signature which was taken from the visitor’s signature book on display at the Bletchley Park Trust in 1947, where Turing did his decryption work during WWII.
  • Just below his signature is a quote from Turing, given in an interview with Time newspaper of June 11, 1949: “This is only a foretaste of what is to come and a shadow of what will be.
  • On the left side of the portrait, ending at his shoulder, we see a ticker showing Turing’s date of birth (June 23, 1912) in binary code. The teleprinter is part of the Turing machine model he developed in 1936.
  • To the left of his head we see a mathematical table and formulas from Turing’s 1936 revolutionary article ‘On calculable numbers, with an application to the Entscheidungsproblem‘. This article is widely recognized as fundamental for computing.
  • On the bottom of the table we see a photo of the Automatic Computing Engine (ACE) pilot machine that was developed at the National Physical Laboratory based on Turing’s pioneering design. ACE was one of the first electronic recorded program digital computers. There is also a series of background images depicting technical drawings from the ACE progress report.
  • Scattered across the banknote we also find technical drawings of the British Bombe, the code-cracking machine specified by Turing, used to crack messages encrypted by Enigma during World War II.
  • Finally, we can see a sunflower-shaped red leaf patch in the upper right corner, with the letters AT (Alan Turing) in the middle. This article is linked to Turing’s study on the question: “How does an organism know how to grow?” To answer this question, Turing developed mathematical and biological models in the early 1950s and used the Mark 1 computer to calculate them.

The fact that Alan Turing was selected to feature on the new 50-pound note is also an important symbol of diversity. In 1952, Turing was arrested and convicted of homosexual activity, an official crime at the time. He had the choice between a prison sentence and hormone therapy for a year, and chose hormone therapy. Only two years later, Turing died at the age of 41. He most likely committed suicide by eating a poisoned apple. In 2009, Prime Minister Gordon Brown formally apologized on behalf of the British government for the conviction of Alan Turing in 1952 for homosexuality: “[…] We are sorry. You deserved so much better.

British CWI researcher Lynda Hardman is also happy with Alan Turing’s new post. “Today, our digital communication was born thanks to Alan Turing and Tim Berners-Lee, the inventor of the World Wide Web. Without them we wouldn’t be talking through Zoom now. “

Hardman sees an interesting parallel between the research of the CWI group Human-Centred data analysis, of which it is part, and the famous Turing test: “In the Turing test, the question is whether a machine can be intelligent. The research we’re doing in Digital Humanities is actually sort of a reverse Turing test: Much of what people have produced in terms of culture over the centuries has now been digitized. The question for us researchers then is: how to extract meaningful human information from all digital data?

Hardman ends by telling a personal anecdote illustrating the importance of Alan Turing as a public figure: decided for Alan Turing. At CWI, we have an original Enigma coding machine, a German machine that Turing helped break during WWII. Anna came to the institute once and was allowed to briefly touch the Enigma. She found it absolutely amazing.

About CWI

Founded in 1946, Centrum Wiskunde & Informatica (CWI) is the national mathematics and computer science research institute in the Netherlands. It is located in Amsterdam Science Park and is part of the NWO Institute Organization. The institute is internationally renowned. More than 150 researchers conduct pioneering research and share their acquired knowledge with society. More than 30 researchers are also employed as professors in universities. The institute has generated twenty-seven spinoff companies.


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