As one of the world’s leading astrophysicists, Professor Jo Dunkley has researched both the mass of the tiniest particle and the size of the universe. Here, she speaks about the thrill of discovery and the untold stories of women in science. “I started off being intent on just writing about the science, but then I realised the stories of the scientists would be just as interesting. Now I’m fascinated about all the people that must be out there who have never been credited.” By Jenny Valentish.

Astrophysicist Jo Dunkley

Professor Jo Dunkley.
Professor Jo Dunkley.
Credit: Suki Dhanda

Rarely, it seems, has a female inventor been struck by the overwhelming urge to bestow her name upon her creation.

On the Wikipedia page “List of inventions named after people”, which comprises nearly 300 entries, six are named after women, each striking for the passivity of its eponym: for instance, the opera singer Nellie Melba, after whom the peach Melba was named; ballet dancer Anna Pavlova, ditto the pavlova; Mae West, after whom the personal flotation device was apparently nicknamed; and Amelia Bloomer, the first woman to own, operate and edit a newspaper for women, whose name was given to voluminous undergarments.

Evidence would suggest that, whether by opportunity or ego, the habit of naming things after oneself tends to be a very male trait. As comedian Hannah Gadsby noted in her latest show, Douglas, the 18th-century physician James Douglas even claimed the empty space between the uterus and rectum as the “pouch of Douglas”.

By contrast, the efforts of female pioneers have often been uncredited, erased, snubbed and even stolen while their colleagues’ achievements are cemented in history. Science has fared no better than other pursuits.

Professor Jo Dunkley, OBE, hopes to change that, in part through her book Our Universe: An Astronomer’s Guide, which unearths some of the overlooked achievements of women in astrophysics, and through a series of public talks, including at the Sydney Opera House’s All About Women festival.

An Oxbridge-educated astrophysicist, Dunkley is professor of physics at Princeton University. Hers has been a meteoric rise in a field that remains dominated by men. Among many awards, she has received the Royal Society Rosalind Franklin Award for her outstanding contribution to science, technology, engineering and mathematics (STEM) and her promotion of women in STEM.

It’s worth mentioning that Rosalind Franklin was a British biophysicist whose work was instrumental in deciphering the structure of the DNA molecule, yet it was her male colleagues who received the 1962 Nobel prize in physiology or medicine. In his best-selling memoir about the discovery, her colleague James Watson complained that “Rosy” was not unattractive but never wore any lipstick.

“I started off being intent on just writing about the science,” Dunkley says, “but then I realised the stories of the scientists would be just as interesting.

“Now I’m fascinated about all the people that must be out there who have never been credited.”

These women include Henrietta Swan Leavitt, an astronomer who worked at the Harvard College Observatory in the early 1900s. “She discovered this important relationship about these passing stars that basically helped us figure out the size of the whole universe, and only now are astronomers pushing to call her discovery the Leavitt law,” says Dunkley. Leavitt’s work became the jumping-off point for Edwin Hubble, of Hubble’s law and the Hubble Space Telescope. He and many others have suggested Leavitt should have been awarded the Nobel prize for her work such was its impact on astronomy.

“A hundred years ago if you were a woman astronomer, you didn’t use telescopes because it was thought to be too physical and perhaps you would have got dirty,” says Dunkley. “The concept of sending women on a journey to Peru to take images would have been unheard of. So, these women had to study the photographic plates that were taken by their male colleagues. Frustratingly, they weren’t in charge of what they were doing, but because they had all this information to look at, they were then able to make these discoveries.”

Even as recently as the mid-20th century, female scientists were obstructed in their research. Vera Rubin, who studied galaxy rotation curves – evidence of the existence of dark matter – had to battle to use the Palomar telescope in California. “The application just said women were not allowed,” says Dunkley, “and the excuse was that there weren’t any restrooms for the women.”

In the past two years alone, a multitude of books have sought to redress this balance, either by highlighting female researchers who have been overlooked, or by analysing the harm caused by research that assumes the male experience is the norm. They include Inferior: How Science Got Women Wrong by Angela Saini, Pain and Prejudice: A Call to Arms for Women and Their Bodies by Gabrielle Jackson, Invisible Women: Exposing Data Bias in a World Designed for Men by Caroline Criado Perez, and the series Forgotten Women by Zing Tsjeng, which includes a book on scientists.

Another urgent battle is being fought on the front lines of Wikipedia. In December, London physicist Dr Jessica Wade – who wrote the site’s entry on Professor Dunkley, among others – tweeted that her articles on women in STEM were being tagged “not notable enough” by an anonymous Wikipedia editor. Earlier last year in Sydney, researcher Dr Melina Georgousakis, founder of the networking group Franklin Women, named after Rosalind Franklin, held a Wikipedia “edit-a-thon”, adding entries for Australian female scientists.


You might imagine that, as children, future astronomers enjoyed stargazing walks with their parents or were given a telescope one Christmas – but Dunkley grew up in London in the ’80s, where the stars were barely visible because of light pollution. Instead, she came to astrophysics through a joy of maths, which she realised could be used to understand the world – and, later, the universe.

“I had no idea about astronomy, I just thought it was a fun way to solve problems, and then at university I started realising how weird and magical astrophysics could be,” says Dunkley. “So I kept at it, but I didn’t have this big dream to be an astronomer, or even a professor. I didn’t think I’d end up in academia.”

Despite her modesty, she emitted a brightness very visible to others. While she was studying for her PhD at Oxford’s Exeter College, the Financial Times heralded her as one of the next big names in physics. Then, when she graduated, she set off to backpack around South America. It was there, engrossed by the night sky above Bolivia, that her love of astronomy was cemented.

Since then, Dunkley’s focus has been on estimating the size and age of the universe. As a research fellow at Princeton, she analysed data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) satellite, which measured the radiant heat from the Big Bang in an attempt to study the properties of the universe as a whole, and the European Space Agency’s Planck satellite, which sharpened the work of WMAP.

She draws deep enjoyment from the fact that answers are so elusive.

“Finding that something was wrong and that we need to find a new theory ... we’re all after that,” she says. “It’s like the ultimate excitement. We all know that fundamental physics isn’t complete – the fact that we can’t describe what goes on inside a black hole and we can’t describe what happened at the beginning of the universe.”

In a typical day, Dunkley spends a few hours with graduate students and junior researchers in her group, reviewing the work they have done. Another hour is spent teaching undergraduate students – “doing equations on the board”. Then she turns to the discussion of data from the Atacama Cosmology Telescope in Chile – 17,000 feet above sea level in a desert mountain range – with a collaboration of researchers from all over the world. Some days she will attend a seminar to hear someone present new results.

“What I love doing, but I have very little time for, is sitting down at my computer and writing software to decode data and find out new things myself,” she says. “Normally, my students do it.”

For the past three years, Dunkley’s team has been working to establish how fast space is growing – a question that directly maps onto the age of our universe. There are currently two measurements in circulation – one from Professor Dunkley’s team and one from another group – and they don’t tally. Dunkley is diplomatic when asked about the discrepancy. “It might just be that someone’s made a measurement wrong or it might be that some new physics is needed to explain that,” she says.

At the other end of the scale, her team is on a mission to measure the mass of the tiniest known particle in the universe, the neutrino – billions of which are passing through your body right now. For that, the researchers are also using the Atacama telescope.

“Until fairly recently, scientists thought neutrinos just flew through space like rays of light and they didn’t have any mass at all,” says Dunkley. “Now we know they have a mass, but we don’t know why. We know they speed out of the galaxies, and clusters of galaxies, and zoom off into the spaces in between them. The more of these tiny particles you have, and the more of the total ingredients of the universe they make up, the smaller the galaxies and clusters of galaxies in the universe are.”

Her team is measuring the degree to which rays of light from very distant parts of space are getting bent. “We can actually weigh all of the stuff in the universe by measuring how much light bends around it,” she says. “This will allow us to weigh the universe, essentially, and then we figure out how much of the universe is made of these really tiny particles.”

Science fiction and ideas embraced by celebrity scientists may make certain theories more exciting to the general public, such as the idea that we’re living in a simulation – “It’s hard to rule that out,” Dunkley concedes – but the theory she gets most animated about is the idea that the majority of stars have their own planetary system.

“It’s a really exciting thing in astronomy now,” she says. “Astronomers thought that probably some of the stars had planets, because our star [the sun] does. But it wasn’t till the last 20 years that they were discovered and now every year the number keeps shooting up from these new technologies that can find them.

“We know our own solar system pretty well, but then when you think about all those stars having a set of their own planets and what they might look like… Some will be rocky, some will be balls of gas, some might be habitable. Probably if you asked most astronomers, most of them would think that some of those planets will have the chance of life.”

As the rest of us fall deeper and deeper inwards into Twitter pile-ons, hot takes of hot takes and the vortex of our phone screens, it’s quite comforting to remember there are those still intent on gazing outwards. One of Professor Dunkley’s missions is to spark that interest in others, be it through her TED Talk or generously patient interviews, in which she’ll scale things down to peppercorns and football fields for ease of understanding.

She says, “I want people to remember that the stuff out there is our bigger home. Yes, we should be trying to protect our Earth, but we’re part of something much bigger and really magnificent. Knowing more about what’s out there, and that there’s so much more out there, helps us put things in perspective. Or they did for me, anyway. Some people talk about it making you feel small or insignificant. To me it makes me feel part of something much bigger.”

This article was first published in the print edition of The Saturday Paper on March 7, 2020 as "Star power".

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Jenny Valentish is the author of Everything Harder Than Everyone Else: Why Some of Us Push Our Bodies to Extremes, and Woman of Substances: A Journey Into Addiction and Treatment.

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