**Please note:** The Alan Turing £50 note display closed on Sunday 13 March 2022.

‘Given the connection between Alan Turing and Manchester, I am really thrilled that the Bank of England has announced that Alan Turing will be on the new £50 note,’ said Sally MacDonald, Director of the Science and Industry Museum, where an exhibit about the shortlisted scientists and Turing is unveiled today.

‘Alan Turing is the mathematical genius credited with cracking Nazi Germany’s Enigma code, shortening World War Two and saving countless lives,’ said MacDonald. ‘Some of his most important work was conducted in Manchester and it is in this city where the campaign began to clear his conviction for the then crime of being a homosexual, which led to his suicide, aged 41.’

The quest began when, speaking in the Science Museum, Governor Mark Carney announced that he sought scientists whose work has shaped how we think about the world and who continue to inspire us today.

If you needed hard evidence of the enduring fascination with science, look no further than the extraordinary response to his request last November.

Over six weeks, 227,299 nominations flooded in. In total, 989 eligible names were put forward who met the bank’s criteria of being real (‘So, I’m afraid, no Time Lords from whatever gender are eligible,’ Mr Carney said), deceased and having had contributed to science in the UK.

The dozen front runners, which can be seen in a special exhibit at the Science and Industry Museum, are dominated by big ideas and figures from physics:

### William and Caroline Herschel, pioneering astronomers

William Herschel (1738–1822) and his sister Caroline Herschel (1750–1848), scoured the night sky to make advances in astronomy.

The 18th century saw science become so chic that George III watched the transit of Venus from his private observatory at Kew and supported the Herschels, after William’s discovery of Uranus (then called *Georgium Sidus*, or ‘George’s Star’) in 1781.

William detected what he thought was a comet but was actually Uranus. the first planet discovered for over two millennia. He may even have spotted its rings.

Caroline, who was the first professional female astronomer, discovered several comets, the first of which she spotted in 1786. They are both celebrated in the forthcoming Science Museum gallery: Science City, 1550–1800: the Linbury Gallery.

### Charles Babbage and Ada Lovelace, computer visionaries

Charles Babbage (1791–1871) and Ada Lovelace (1815–52) helped anticipate the computer age with the former recognising the huge potential for machines to make calculations more quickly and accurately than humans, designing a mechanical calculating machine, the Difference Engine, able to produce tables of numbers.

In 1833, aristocratic mathematician Ada Lovelace became fascinated by Babbage’s designs for a more powerful machine, the Analytical Engine, which he hoped would be able to receive instructions to solve any mathematical problem. Lovelace’s insight was that it could use numbers to represent not just quantities, but any kind of data, which is the central concept of modern computing.

### Mary Anning, celebrated fossil hunter

Mary Anning (1799–1847), became famous for the discoveries she made in her hometown of Lyme Regis. Aged just 12, she and her brother Joseph uncovered the five metre, fossilised skeleton of a 200-million-year-old marine reptile, later known as an Ichthyosaurus.

New, more complete ichthyosaur remains were discovered, followed by a complete skeleton of the long-necked marine reptile Plesiosaurus, the ‘sea-dragon’ in 1823. This was followed by the ‘flying-dragon’ in 1828, later known as a Pterodactyl, and others.

Her discoveries had a huge impact on palaeontology, and the creatures that abounded in pre-historic times which became central to the development of new ideas about the history of the Earth.

### James Clerk Maxwell, unifier of science

James Clerk Maxwell (1831–79), helped lay the theoretical foundations of many innovations that have transformed our way of life. His greatest achievement was to formulate a theory that united electricity, magnetism and light, revealing them to be manifestations of the same phenomenon.

His theory was ground-breaking, predicting the existence of electromagnetic waves and proposing that light is a form of electromagnetic radiation. Maxwell’s theory of electromagnetism paved the way for a new age of telecommunications and, on the centenary of his birthday, Albert Einstein hailed Maxwell’s work as the “most profound and the most fruitful that physics has experienced since the time of Newton”.

### Stephen Hawking, inspirational cosmologist

Stephen Hawking (1942–2018), worked relentlessly to unravel the mathematical secrets of the universe. Diagnosed with motor neurone disease at the age of 21, he was told he’d have only two more years to live. Yet in the decades that followed, Hawking would turn cosmology from a fringe subject into arguably the most compelling of all the sciences.

In 1974, Hawking brought together laws about how invisibly small things behave, quantum theory, with the theory of how gravity works, general relativity, to show that that despite the huge gravitational pull of black holes, so great that light itself cannot escape, they would bleed off what is now called “Hawking radiation” and gradually evaporate. Physicists continue to explore the impact of his surprising discovery.

Hawking published A Brief History of Time in 1988, which became an international bestseller. Communicating complex ideas with clarity, the book established his fame, inspiring curiosity in millions of readers.

### Ernest Rutherford, founder of nuclear physics

Ernest Rutherford (1871–1937), uncovered the properties of radiation, revealed the secrets of the atom and laid the foundations for nuclear physics.

When he arrived at the University of Manchester in 1907, New Zealand born Rutherford had already transformed understanding of radioactivity. He had identified two kinds of radiation, alpha and beta, and shown that radioactivity results from the breakdown of atoms into new ones, earning him the Nobel Prize in Chemistry in 1908.

In 1911, after experimenting with gold foil in his Manchester lab, Rutherford was astounded when he spotted alpha particles being strongly deflected. He famously said: ‘It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you… it was then that I had the idea of an atom with a minute massive centre, carrying a charge.’ The experiment paved the way for the model of atomic structure we use today.

### Paul Dirac, first truly modern theoretical physicist

As a mathematics student Paul Dirac (1902–84), became fascinated by the emerging field of quantum mechanics, the most revolutionary theory of the 20th century, which deals with the universe’s tiniest particles.

He wanted to understand how small particles called electron behave as they travel close to the speed of light. And to do this, Dirac had to marry two theories: quantum theory and special relativity

Dirac’s explanation produced one of physics’ most revolutionary equations. In 1929 he claimed: ‘The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known.”

Using his equation, Dirac also proposed that all particles have an almost identical, oppositely charged antiparticle. Predicting the existence of antimatter before it was found in the real world earned Dirac the Nobel Prize in Physics in 1933. For Dirac, mathematical beauty was ‘almost a religion’.

### Srinivasa Ramanujan, mathematical genius

Srinivasa Ramanujan (1887–1920), was raised in Southern India and, as a result of his profound mathematical intuition, the then clerk at the Accountant-General’s office at the Madras Port Trust Office was invited to Trinity College, Cambridge.

There the eminent British mathematician Godfrey Harold (G. H.) Hardy and his collaborator John E. Littlewood, recognised the raw talent of Ramanujan, who ascribed his profound mathematical insights to Namagiri, a local incarnation of Lakshmi, the Hindu goddess of good fortune.

Ramanujan published over 20 papers in Cambridge. In 1918, two years before his premature death, he became the first Indian mathematician elected as a Fellow of the Royal Society. His visceral insights enabled Ramanujan to excel in pure mathematics, notably number theory, a field that focuses on whole numbers, how to build them, how they behave and how they interact.

Among his achievements, Ramanujan built a bridge between number theory and analysis, another field in mathematics, which was extraordinary because the former mostly focuses on whole numbers and the latter on continuously-changing quantities.

### Dorothy Hodgkin, UK’s first female Nobel prizewinner

Dorothy Crowfoot Hodgkin (1910–94), used a beam of x-rays to explore the structure of materials. The rays bounce off the atoms. Although they cannot be focused, they form patterns which can be used to calculate the molecule’s 3D structure. By the use of early computers, she boosted the power of a technique called X ray crystallography so that it could reveal the structure of complex molecules found in nature.

Penicillin was of the greatest medical advances of the last century. Yet as early as 1945, discoverer Alexander Fleming recognised that the drug’s overuse could drive the evolution of resistant bacteria. It would take the X-ray studies of Hodgkin to reveal the molecular structure of penicillin so that we could understand how resistance was emerging, the first step towards developing new antibiotics.

We have her model of the structure in our collections. At that time, it was the largest molecule ever to have been solved by X-ray methods.

This was just the first of several significant contributions she made to science, including revealing the structures of vitamin B-12 and insulin. Modern structural biology of the kind pioneered by Hodgkin still plays a key role in the fight against infectious disease and she was the favourite candidate for the £50 note of Science Museum Group Director, Sir Ian Blatchford.

### Frederick Sanger, double Nobel prizewinner

Frederick Sanger (1918–2013), earned his first Nobel prize in 1958, for his research on the structure of proteins, when he worked out the order of the 50 or so amino acids that make up the insulin molecule.

His work revealed how the DNA code specified linear strings of amino acids in proteins, and that proteins were not agglomerations of closely-related substances, as many thought in the first half of the 20th century, but were indeed a single chemical.

The biochemist was one of the greatest innovators in genetics of all time with his emphasis on developing new techniques, notably DNA sequencing, the ability to read the genome, or genetic recipe, of an organism, while working at the Medical Research Council’s Laboratory of Molecular Biology in Cambridge.

He unveiled his first partial DNA sequence in May 1975 and went on to deliver the first complete determination of the sequence of a DNA molecule: the 5375 ‘letters’ in the genome of a bacterial virus called phi-X174. Sanger also sequenced the 17,000 or so letters of DNA in the human mitochondrion, the energy factory found in our cells. This feat can be regarded the first human genome project. He won the Nobel prize for this work in 1980.

### Rosalind Franklin, DNA pioneer

Rosalind Franklin (1920–58), played a key role in the momentous discovery in 1953 of the double helix structure of the molecule in our cells that forms our genes, a twisting pair of strands of deoxyribonucleic acid (DNA) that has been unravelling to replicate itself since the dawn of life some four billion years ago.

Franklin directed beams of x-rays at crystallised DNA molecules. The rays bouncing off them produced patterns that gave the vital clue to James Watson, Francis Crick and Maurice Wilkins, the scientists who won the Nobel Prize in Physiology or Medicine in 1962 for cracking DNA’s double helix structure (Franklin died of cancer in 1958).

Wilkins had been on to the idea of helices since 1951 but his boss John Randall had soured Wilkins’s relationship with Franklin (Randall had implied in a letter to her that DNA would be her project alone), and she was both uninterested in building models and dismissive of the idea of a helix.

Even so, her data, which she did not directly share, would prove vital: Watson recalled her photograph 51 was a revelation, because it “was so perfect”. And she provided insights into the relationship between the bases (the chemical ‘letters’ of the code) and DNA’s supporting structure of phosphate groups.

### And the Bank of England’s choice is….Alan Turing, our greatest codebreaker

Alan Turing (1912–54), was a mathematician, logician, cryptanalyst, and philosopher, best known for his work as the codebreaker who helped shorten World War 2 and for his efforts to lay the mathematical foundations of the modern computer.

The theoretical “Universal Machine”, proposed by Turing in the 1930s before his famous code breaking work at Bletchley Park, was an imagined device which could be programmed by symbols read on a tape.

Turing’s mathematical model provided the foundation on which modern computing is based and was innovative enough to come top in an online poll of more than 50,000 voters held by the Science Museum in 2013 as part of National Science and Engineering Week.

After the war, he moved to the National Physical Laboratory in Teddington. Here he devised one of the first practical designs for a stored-program computer, called the Automatic Computing Engine or ‘ACE’.

In 1948, Turing joined Max Newman’s Computing Machine Laboratory in Manchester and wrote the operating manual for the Ferranti Mark I installed there in February 1951, the world’s first commercially available computer.

Throughout his life he pursued the question of mind and body, and his ‘Turing test’, sketched out in his seminal 1950 paper ‘Computing machinery and intelligence’, is seen as a litmus test of artificial intelligence. He also did pioneering work on the patterns of nature, supported recently by a citizen science experiment at the Science and Industry Museum.

Turing was convicted in 1952 under laws that prohibited homosexuality and was posthumously pardoned in 2013 after leading figures, including Professor Stephen Hawking and Sir Paul Nurse (both Science Museum Group Fellows), and Lords Faulkner and Grade (Trustees of the Group) lobbied the Prime Minister to posthumously pardon Turing.

To select this shortlist, the bank’s Banknote Character Advisory Committee was augmented by space scientist Maggie Aderin-Pocock, author and genetics expert Emily Grossman, professor of the history and philosophy of science at the University of Cambridge Simon Schaffer, and bestselling science writer Simon Singh.

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