Women who made modern technology possible

Over the past year or two I’ve been collecting examples of extraordinary women whose technical achievements have made the modern world possible. The contributions made by some of them have become more well known in recent years, while others remain relatively (and unjustifiably) obscure.

Rather than simply keeping the list to myself, I thought I’d publish it. And so, in chronological order by date of birth…

Ada Lovelace (1815–1852)

Perhaps the most well-known name on this list, Ada, Countess of Lovelace, was a mathematician and probably the first computer programmer. She was fascinated by the proposed (and still unbuilt) Analytical Engine, and translated and expanded upon an Italian-language article describing the Engine. In her expanded notes, she included an algorithm for computing Bernoulli numbers with the Analytical Engine: the first ever computer program.

Katharine Burr Blodgett (1898–1979)

Katharine Burr Blodgett was a researcher on the borders between chemistry and physics, who worked for most of her life at General Electric. She was the first woman to be awarded a Ph.D. in Physics from Cambridge University. Among many other discoveries, she devised a reliable way to deposit single-molecule-thick coating layers on glass. This led directly to the development of nonreflective coatings (AKA “invisible glass”), which have been used in cinema and photography ever since.

Grace Hopper (1906-1992)

Another mathematician, Grace Hopper studied at Yale and went on to teach at Vassar, becoming an associate professor by the age of 35. In WWII she enlisted with the US Navy, where she became one of the first programmers of the Harvard Mark I. After the war, she worked on the UNIVAC, and was instrumental in developing the compiler – a tool that could convert code written by humans into code suitable for a machine – starting with a language and link-loader tool called A-0. Developments on the “A” series of languages and compilers led directly to the invention of COBOL.

Hedy Lamarr (1914-2000)

Already a successful Hollywood actor by 1940, Lamarr is another woman on the list who turned her attention to solving problems for the war effort. She turned her self-taught intellect on a number of different problems, but her lasting impact on the modern world is through her invention of Frequency-hopping spread spectrum techniques, initially designed to prevent tracking or jamming of torpedo radios, but now a core technology in mobile phone networks (as CDMA), Wi-Fi, and Bluetooth.

Betty Holberton (1917-2001)

Betty Holberton, like many women in the early history of computers, was one herself. She was hired by the Moore School of Engineering as a “computor” and shortly afterwards became one of the six original programmers of the ENIAC, one of the many machines that claims to be the first general-purpose programmable computer. After the war, like Grace Hopper, she ended up working on the UNIVAC where she helped write the first program that generated a computer program (known as SORT/MERGE), as well as the first computer statistical analysis tools, which were used in the 1950 US Census.

Erna Schneider Hoover (b. 1926)

Once upon a time, busy telephone exchanges were extremely noisy places. Incoming calls were routed to their destination by stepping switches, electromechanical devices which rotated a set of electrical contacts mounted on a “wiper” in order to interconnect the correct circuits. Today, telephony switching is purely electrical: switching machines are orders of magnitude smaller, and can switch orders of magnitude more circuits using orders of magnitude less energy. None of this would be possible without Erna Schneider Hoover’s invention of Stored Program Control in the early 1950s. Schneider Hoover received one of the first software patents for her work.

Margaret Hamilton (b. 1936)

I hope that Margaret Hamilton requires no introduction. The photograph of her standing next to the code listings for the Apollo Guidance Computer has become a well-known reminder of her place in technology history. During the space race in the 1960s, she was Director of the Software Engineering Division at the Draper Lab and had overall responsibility for the development of the software that took Apollo to the moon and back. In fact, it seems likely that the term “software engineering” itself was coined by Hamilton:

During [the time of the Apollo space missions] at MIT, she wanted to give their software “legitimacy”, just like with other engineering disciplines, so that it (and those building it) would be given its due respect; and, as a result she made up the term “software engineering” to distinguish it from other kinds of engineering. [source]

In 2016, Hamilton was awarded the Presidential Medal of Freedom, the US’s highest civilian honour.

Barbara Liskov (b. 1939)

In 1968, Barbara Liskov was awarded her Ph.D. – on artificial intelligence approaches to chess endgames – making her one of the first women in the US to earn a doctoral degree in computer science. In the nearly fifty years since, she has become recognised as one of the world’s foremost researchers in the field of programming languages and distributed systems: she received the von Neumann medal in 2004, and the Turing award in 2008.

Among her many contributions to these fields, she is most well-known for the Liskov substitution principle, the “L” in the SOLID mnemonic for object-oriented design principles. The substitution principle lays out an intuitive meaning of “subtyping” in a programming system: that objects in a program should be replaceable with instances of their subtypes without altering the correctness of the program.

Radia Perlman (b. 1951)

The Spanning Tree Protocol is one of the many technologies that make the internet possible. Without it, we would either a) not have any large computer networks, or b) all large networks would be impossibly fragile: no redundant network links could be added, because they would introduce loops around which traffic would travel forever.

Instead, Radia Perlman’s STP and its descendant algorithms are used to build a loop-free topology for Ethernet networks on top of a physical topology which may include redundant links. Like several other members of the list, Perlman is a graduate of MIT, where she earned her Ph.D. in 1988. She is the author of one of the seminal textbooks on network routing and bridges.

Susan Kare (b. 1954)

The typography and iconography of the original Macintosh were in no small part the work of Susan Kare, who joined Apple in 1982. If you’ve used Macs for any length of time, you’ll remember the “Happy Mac” icon, and possibly the original trashcan icon or the Dogcow. But it seems likely that the contribution of Kare’s that made it into the most hands was the Chicago typeface which was used by the original iPod in 2001 and continued to be at the heart of the iPod’s user interface until the iPod Photo was released in 2004.

Sophie Wilson (b. 1957)

Of all the women on this list, Wilson is certainly one of the most egregiously underrecognised. It is overwhelmingly likely that you are holding her work in your hands as you read these words, as nearly every smartphone contains one or more processors based on the ARM instruction set, which she designed in 1983. By 2012, this instruction set and processors based on it were part of more than 95% of all smartphone devices.

Before developing the ARM architecture, Wilson was part of the small team that designed the computer that became the BBC Micro, a device used by generations of schoolchildren in the UK, and which gave many of them (including me!) their first experience of computer programming.

If I know one thing about this list, it’s that it is incomplete. For generations, women’s contributions to science and technology have been ignored, forgotten, or actively stolen from them by men. If you know of women who should be on this list, please email me (I’m nick at this domain) so I can learn about them and add them to it.