An Interview with Dame Professor Jocelyn Bell Burnell

It’s not an exaggeration to claim that our understanding of the Universe took a giant leap forward back in 1967. That was the year Dame Professor Jocelyn Bell Burnell (a PhD student back then), noticed something strange in her data. Some “scruff”.

On the 28th November that year, when reviewing the squiggly lines of the chart recording taken by the Interplanetary Scintillation Array - a radio telescope she helped build - located at the Mullard Radio Astronomy Observatory, Professor Bell Burnell confirmed this scruff that she had first uncovered from the observations dated the 6th August, recognising it was a repeating astrophysical signal.

The “scruff” turned out to be something extraordinary - the electromagnetic signature of a new class of celestial objects: a rapidly rotating neutron star that beams radio waves from its magnetic poles. With each rotation, these beams sweep past Earth like a lighthouse scanning the sea, producing the rhythmic flashes of radio light. Pulse. Pulse. Pulse.

As news spread of the exciting discovery, Anthony Michaelis - a journalist from the Daily Telegraph in London - coined the term “pulsar” to describe them. The name quickly caught on and was adopted by the astronomy community. The first pulsar was found, and it not only revolutionised astrophysics, it also helped launch whole new fields of science. 

Today, Professor Bell Burnell remains one of the most influential and respected figures in all of astronomy - not only for her pioneering work on pulsars, but also for her tireless advocacy in making the scientific community more inclusive, fair, and diverse. She has inspired generations of scientists (including this one!) with her intellect, humility, and humanity.

I had the honour and privilege of sitting down with Professor Bell Burnell for a one-on-one interview during her visit to Sydney this week. She was in town to receive an Honorary Doctorate from the University of Sydney and took part in a range of events and activities - including a day spent engaging with local early-career scientists about the exciting astronomy being carried out across Australia. We spoke candidly about pulsars, her legacy, and the importance of building a scientific culture that celebrates both discovery and equity.

The discovery of pulsars by Professor Bell Burnell was made during her doctoral research at Cambridge. Combing through the miles of recorded chart papers, there amongst the noise, Bell Burnell noticed a signal that repeated every 1.3 seconds. The signal also followed the same patterns of a sidereal day, indicating that it could not be a terrestrial-based source (like radio frequency interference - RFI) but instead, it was astrophysical in nature.

At the time, neutron stars were theorised (as far back as the 1930s, in fact), but there was not much conversation about this in the astronomy community. Radio astronomy itself was only just starting to gain momentum. This discovery confirmed the existence of neutron stars for the first time, but it was also not as simple as shouting Eureka! from the rooftops, and it took careful analysis and then convincing to tell the world about this.

Professor Bell Burnell, along with her colleagues, helped build the Interplanetary Scintillation Array, and so, she understood the telescope very well, as it was part of her daily routine.

“My sole responsibility was running the survey, which really meant going out to the observatory to put fresh paper in the chart recorders and switch the settings, which had to be done manually as there was very little computing facility at that time,” she said. 

“I typically spent mornings out at the observatory doing the routine maintenance, collecting the previous day's records, then in the afternoon I went back to the laboratory in the centre of Cambridge to analyse the data”

Upon seeing the signal, she immediately recognised something was different about this.

“I got quite good at identifying RFI because with a very large collecting area, the telescope picked up a lot of RFI. But this signal was different - and again, I wanted to be careful and thorough”

“What’s this funny signal?” pondered Bell Burnell at the time. A critical aspect of this discovery, rooted in her own intuition and the accumulated hard work and training she had undertaken up until this point, came next.

“Then I twigged that I had seen it before, and it was at the same right ascension - which suggests it's not human interference”

It was at this point, that astrophysics changed forever.

However, it was also Professor Bell Burnell’s third year of her PhD, so she had to convince her supervisor (who was cautious in his approach) that this was a real astrophysical signal.

Further recognition of the pulse-like nature of this signal came when the chart paper was run through the machinery at a faster rate, producing a high-time resolution that showed the period peak rising and falling. Eventually finding a second object of this nature, then a third and fourth - each with a different pulse rate - delivered the confirmation required - this was something extremely exciting and new, unlike anything we humans had ever seen before.

Since the discovery in 1967, thousands of pulsars have now been catalogued, and an entire zoo of neutron stars - with various sub-categories -  now exists. This includes the canonical pulsars (recently born from supernovae), the much older millisecond pulsar population (which have had their pulsar engines restarted through binary accretion and rotate much more rapidly), magnetars (the most extreme magnetic objects in our Universe), and a suite of other weird and wonderful types. 

The connection between high-energy astronomy, such as gamma-ray and x-ray emissions, has also opened up a new method of finding and observing pulsars, which is particularly informative when coupled with radio observations. Many pulsars have been discovered as a result of first identifying gamma-ray pulsations and then pointing radio telescopes towards the same source, confirming that there are indeed pulsars there.

Despite these multi-wavelength advances, Bell Burnell notes that radio astronomy remains the most powerful and efficient way to discover pulsars and understand their broader population. 

“Well, it’s [radio wavelength searches] the simplest way to find them. So you get a good sample of the population through the radio emission. It’s really the key way to find them if they don’t do a lot at other wavelengths. So, the radio emission is important for finding these things and thereby getting a sense of what the population is like.” 

Professor Bell Burnell herself also went on to work at other electromagnetic wavelength regimes across her career, such as x-rays and infrared astronomy. 

These days, pulsars are used for many aspects of astrophysics, including using them as cosmic clocks to study matter in extreme environments, probes of magnetic fields, determining the properties of the interstellar medium, searching for gravitational waves (both high and low-frequency regimes), and fundamental physics like tests of General Relativity. Looking back to those early years, Bell Burnell admits that none of this breadth was apparent when pulsars were first discovered, when I asked her if she could imagine how much science would come from her discovery.

“No, I don’t think I could. To begin with, we didn’t know what their astrophysical origins were. When it became clear that they were supernova remnants, you began to see how they fitted into the scheme of things, but until they found the one in the Crab Nebula, it wasn’t clear what the origins of these things were.”

Even today, as presented at the Science Symposium by Australian early career researchers, new discoveries continue to surprise astronomers, including a recently emerging class of “long-period transients,” which don’t fit neatly into existing models of pulsar behaviour. Professor Bell Burnell views these mysteries as reminders of how dynamic and exciting the field still is.

“That is part of the fun of astrophysics - there’s new stuff discovered quite regularly, to be honest. I’d say give it 18 months and we’ll have an explanation [with regards to the long-period transients].”

It’s that sense of curiosity and openness to surprise that remains at the heart of what excites her about pulsar astronomy today. As technology advances and telescopes become more sensitive, the field is uncovering phenomena that were once invisible and not even considered.

“Astronomy is very lively, and one of the interesting developments in my lifetime is that the equipment has gotten better, and our integration times have shrunk. We are seeing much more time variability than we have previously - probably more than we even expected - so that’s a growing area, which is quite exciting.”

Pulsars are not the only contribution that Professor Bell Burnell has made to the field of science. She has also been a leading voice for diversity and equity in academia.

In the UK, she helped establish the Athena-SWAN initiative, which benchmarks and rewards academic institutions for promoting and applying positive practices when it comes to gender equality in higher education and research. The program has become such a success that it has since spread internationally, with long-term sustainable impacts, shaping policies across universities globally. Here in Australia it is known as SAGE (Science in Australian Gender Equity).

When I asked her what first motivated her to focus on this kind of institutional reform, Professor Bell Burnell explained how the idea was born from collaboration and a touch of ingenuity.

“There was a group of about half a dozen female scientists of my sort of age who got together in a room at the Royal Society in London, to think what we could do to improve the position of women in science, which included biological sciences, physical sciences, computing sciences,” she said. 

“We struggled until one of us said: You know, University Vice-Chancellors - they’re competitive guys (they were all men at that stage). If we create a competition for the most women-friendly university, then they will compete, and she was right!”

We both had a good chuckle about how clever this strategy is.

“So we announced the competition - the prize was a glass rose bowl - and ran the competition, and the first time around, there were probably around six or eight entries, and we selected the best and had a little ceremony and awarded the glass rose bowl. Did it again for a second year, with slightly more entries. Assessed them and awarded the glass rose bowl again.”

“By that stage, from all the applications we had received, we could see things that were working and also see things that didn’t seem to work so well. So we were able to put together, basically, a questionnaire looking for answers on those areas where we could see that several universities had good ideas and had made a bit of progress.”

The initiative soon gained traction beyond its creators, with Professor Bell Burnell reflecting on handing the reins over as the project scaled.

“The research council, the funding body, became interested, and after we’d run the project for two or three years, they offered to take it over. So fairly soon, the funding body was taking an interest in the issue of gender balance in science departments and the progress of the minority gender in particular. So that was good, and that mainstreamed it.”

In 2018, Bell Burnell was awarded the Special Breakthrough Prize in Fundamental Physics (one of the world’s most prestigious scientific honours) - worth £2.3 million, in which she donated the entire sum to fund scholarships for underrepresented minorities seeking to study physics. The decision was both practical and profoundly symbolic, reflecting her belief that true progress in science must include everyone who has the curiosity and courage to contribute.

“[The funding] was doing several things, it was changing - at least - the regular make up of physics departments by introducing women and other minorities which we thought was good for the department, but in particular it was giving a chance and an affirmation to students who were from a minority and probably felt they were struggling a bit because they were a minority.”

That fateful discovery in 1967 is now a part of the cultural fabric and story of astronomy, and Professor Bell Burnell herself has become a symbol of perseverance and inspiration. Her story is often told to young scientists - especially from underrepresented groups - as a reminder that breakthroughs can come from anyone, anywhere.

What keeps Professor Bell Burnell inspired these days is not only the science, but the people - the students at the forefront of research, her colleagues that she collaborates with, and the community she continues to shape. During the Science Symposium, prior to this interview, I kept glancing over at her listening and giving her full focus to the early career scientists presenting their findings - something I know that they will always cherish to have had the opportunity to do.

As we look into the future of pulsar astronomy, with new and more sensitive instruments about to come online, coupled with multi-messenger astronomy that new generations of researchers are collaborating on, it is the foundations laid by Professor Bell Burnell that will remain as needed and relevant as ever.

Her story is not just about pulsars, it's about resilience in the face of bias, of generosity in sharing recognition, and of a vision to build a more inclusive scientific community.

As we wrap up the interview, the little voice inside my head reminds me (someone who is currently doing a PhD in pulsar astronomy) that Professor Bell Burnell’s important work, throughout her career across science, is not only about exploring the Universe, but also about fostering the communities of people who dare to push the boundaries of curiosity and discovery. 

With special thanks to Emiratus Professor of Astrophysics Anne Green, Dr Manisha Caleb and Dr Laura Driessen from the University of Sydney, as well as Sydney Ideas, for the opportunity to participate in the Science Symposium, conduct this interview, and for being accommodating with the venue and organisation.