And, in 1967, when she spotted the first four light sources with repeated pulses beating a steady rhythm against the background noise of the stars, it was Bell Burnell who realized she'd detected something important. She had discovered the swiftly spinning cores of collapsed stars, whose powerful magnetic fields produce jets of radiation that flash across the sky like the rotating beam of a lighthouse.
The objects, called pulsars, are among the most important astronomical finds of the 20th century — potent tools for testing physics, probing space-time and investigating the dark regions of the universe.
On Thursday, half a century after her pioneering work, it was announced that Bell Burnell will receive a $3 million Breakthrough Prize, one of the most lucrative and prestigious awards in science. The special award in fundamental physics, given for her scientific achievements and “inspiring leadership,” has only been granted three times before.
To Bell Burnell's admirers, the prize is richly deserved and somewhat overdue. In 1974, when a Nobel Prize in physics was awarded for the discovery of pulsars, Bell Burnell's adviser Antony Hewish was one of the recipients. Bell Burnell was not. No woman has won the Nobel Prize in physics since 1963.
"She represents something very important in our recent history,” said Janna Levin, an astrophysicist at Barnard College of Columbia University. “She has tenacity, and ingenuity, and originality of thought, and a long legacy as an astronomer . . . that reaches into all branches of physics. I'm absolutely thrilled."
Like the stars of “Hidden Figures” and DNA researcher Rosalind Franklin, Bell Burnell’s personal story embodies the challenges faced by women in scientific fields. Bell Burnell, who was born in Northern Ireland in 1943, had to fight to take science classes after age 12.
“The assumption was that the boys would do science and the girls would do cookery and needlework,” she said. “It was such a firm assumption that it wasn’t even discussed, so there was no choice in the matter.”
But Bell Burnell would not be denied. She had read her father's astronomy books cover to cover, teaching herself the jargon and grappling with complex concepts until she felt she could comprehend the universe. She complained to her parents, who complained to the school, which ultimately allowed her to attend lab along with two other girls. At the end of the semester, Bell Burnell ranked first in the class.
By her junior year at the University of Glasgow, she was the only woman enrolled in honors physics. Men would whistle and heckle her when she walked into the lecture hall. Blushing only made them louder, so she trained herself to be stoic.
When she arrived at Cambridge University for graduate school, Bell Burnell was certain someone had made a mistake admitting her. She was one of two women in her graduate program, and Cambridge was far more affluent than anywhere she had lived before. Both factors, she said, probably contributed to her impostor syndrome — doubts about her accomplishments and a persistent fear of being exposed as a fraud — “although, of course, we didn’t know that term then.”
"Surely they're going to realize I'm not bright enough,” she recalled thinking. “But until they throw me out, I’m going to work my very hardest."
Bell Burnell joined Cambridge's radio astronomy department, where her adviser, Hewish, was on the hunt for quasars — incredibly bright objects in the distant sky whose origins were then unknown.
Hewish had designed his own telescope for the task: a four-acre network of copper wires dubbed “Interplanetary Scintillation Array.” The wires would pick up the energy of radio waves streaming down from the cosmos and send an electric pulse to a pen recorder, which marked the signals on rolls of chart paper. The resulting plots resembled the dips and peaks on a cardiogram; studying them was like monitoring the heartbeat of the universe.
After construction on the telescope was completed, Hewish assigned Bell Burnell to retrieve and analyze the information it collected. Just before lunch one day in the summer of 1967, the young physicist noticed an “unclassifiable squiggle” on one of her data sheets. It was the kind of detail that others might have disregarded or overlooked; indeed, Hewish initially insisted it was merely interference. But Bell Burnell's fear of flunking made her meticulous, and a lifetime of feeling like an outsider had opened her mind. She remained focused on the squiggle until she could figure it out.
The signal was remarkably regular, pulsing every 1⅓ seconds. And rather than keeping to a 24-hour schedule — as would be expected if it was produced by “Joe Doke driving home every day in a badly suppressed car,” Bell Burnell said — it followed “sidereal time,” which governs the movement of the stars. Estimates of its distance pegged it to a spot in the constellation Vulpecula, about 2,000 light-years away.
Hewish and Bell Burnell jokingly christened their discovery “LGM-1" or “Little Green Man.” They couldn't come up with any explanation for a signal so regular. Why not aliens?
Then, on a frigid morning just before Christmas, Bell Burnell noticed a second pulsing signal coming from another part of the cosmos. Seeing the faint smudge on the telescope readout filled her with elation.
"When you get a second one of something it makes the first one so much more believable,” she said. “This begins to look like a new kind of star of which there’s probably a whole lot in the sky."
'It was my stars'
Soon Bell Burnell discovered her third and fourth LGM signals, and in February 1968, the finds were announced via a paper in Nature, one of science's most esteemed journals. Hewish's name was the first listed on the study, Bell Burnell's was second. She was 24.
"The radiation seems to come from local objects within the galaxy,” the scientists wrote. They speculated that it might be associated with a white dwarf, the husk of a star that has burned through all of its nuclear material. Or it could have been a neutron star — the dark, dense nugget left behind after a stellar explosion in which all the matter of a massive star is collapsed into a space the size of Manhattan.
The existence of neutron stars had been theorized but never demonstrated. Making something so dense would require gravity to overcome the forces that give atoms their structure. “You'd end up with something that has been crushed beyond all recognition into a state of matter that hasn't been known before,” said Levin, the Barnard astrophysicist.
Meanwhile, the Nature paper generated huge amounts of publicity for the researchers. In interviews, journalists would ask Hewish to explain the scientific significance of the discovery, then turn to Bell Burnell “for what they euphemistically called the 'human interest,' " she recalled wryly.
Reporters wanted to know her bust size and how many boyfriends she had. A photographer asked her to open one extra button on her blouse.
"It was very unpleasant,” Bell Burnell said. “I would have loved to tell them to get lost. But I was still a student. I needed a reference from the laboratory, and they needed the publicity.” So she smiled and claimed to have forgotten her body dimensions. And then she went back to investigating one of the most exciting mysteries in astrophysics.
No one had yet figured out what the pulsing signals were. In the attic room above the observatory, she, Hewish and 13 other graduate students — all men — eagerly exchanged ideas about the objects' origins.
"I loved the excitement of the chase,” she said, “trying to understand what these things were and why they behaved the way they behaved."
At the end of 1968, several teams of astronomers reported detecting a regular radio flash coming from the heart of the Crab nebula — the cloud of gas and dust left behind after a supernova lit up the sky in 1054.
This confirmed one of Bell Burnell and Hewish's theories: The signals came from pulsars — a subset of neutron stars with intense magnetic fields accelerate particles into two powerful beams that blast from either pole. Each time the star spins, the beam briefly becomes visible from Earth, resulting in a periodic, predictable pulse.
Bell Burnell earned her PhD — the pulsar discovery was part of her thesis — and was working at University College London when, in 1974, a colleague came “steaming” into her office. The Nobel Prize for Physics had just been announced, and her name had not been mentioned.
"I think he expected me to be angry,” Bell Burnell recalled. Yet she was delighted. She hadn't expected to be acknowledged — graduate students rarely were. But this was the first time the physics Nobel had ever been granted to someone studying the stars.
"Finally the committee recognized there was good physics in astronomy,” she said. “I recognized that it was a huge precedent, and I was rather proud that it was my stars that did it."
Bell Burnell said she harbors no ill will toward the Nobel committee, pointing out that she's received just about every other honor conceivable: fellow of the Royal Society, president of the Institute of Physics, Dame Commander of the Order of the British Empire. “I get a party almost every year for one thing or another,” she said.
But other researchers see her exclusion as an injustice.
"She helped build the array she used to make the observation. She is the one who noticed it. She is the one who argued it's a real signal,” said Feryal Özel, an astrophysicist at the University of Arizona who studies neutron stars. “When a graduate student takes that kind of lead in her project, it’s hard to play it down."
Özel noted that only two women have received the Nobel Prize in physics, and none in the past half-century. This despite the fact that women researchers have pioneered the field of nanoscience, established the existence of dark matter, explored strange new kinds of particles and helped to map the universe.
"Women are underrepresented,” Özel said. “I think that it’s great [Bell Burnell] made her peace with it. But it is not something we as a community today want to see happen."
The realization that pulsars exist “was an incredible discovery,” said Alice Harding, an astrophysicist at NASA's Goddard Space Flight Center. “But I don't think anybody understood then how important pulsars were going to become."
In the past five decades, an extraordinary array of astronomical discoveries has emerged from research on pulsars. Their regularity makes them ideal time keepers, more precise even than atomic clocks. Their occasional twinkle revealed that there was stuff in the dark and seemingly empty space between stars — helping scientists to figure out what constitutes the interstellar medium. The first confirmed exoplanets were discovered orbiting a pulsar in the constellation Virgo, and the extreme conditions at their centers have enabled some of the most stringent tests of Einstein's theory of general relativity.
The detection of pulsars suggested that another hypothetical phenomenon — a black hole — might also be real. If the laws of physics allowed a dying star to fall in on itself until its very atoms were smothered, why couldn't the collapse go farther, until an entire star's worth of matter is packed into a single, invisible point?
Observations of Cygnus X-1, a powerful source of X-rays in our galaxy, revealed that the black-hole theorists were right: There are bodies so dense that their gravity is powerful enough to prevent even light from escaping.
Pulsars can also serve as “cosmic lighthouses” — important points of consistency in the vast and ever-changing cosmos. When the Golden Records — twin messages conveying sounds and images about life on Earth — launched on board the Voyager spacecraft in 1977, their covers bore an image showing the location of the sun relative to 14 pulsars. If alien explorers or space-faring humans came across the records sometime in the distant future, scientists hoped the pulsar “maps” would help identify the far-flung planet from which the spacecraft came.
Back on Earth, Bell Burnell's career was sometimes stymied by the strict social conventions of her era. Her family moved frequently for her husband's job. Each time she arrived in a new city, she would have to write a “begging letter” to the nearest observatory asking for work. She wound up with a “fantastic miscellany of jobs,” studying the universe in every conceivable wavelength of light: X-ray, gamma ray, radio wave, infrared. But each time she worked her way to a top position within an organization, the Burnells would move, and she'd have to start over again.
"Do you have a game called snakes and ladders?” she said. “That was my career."
It was a constant battle to keep doing science. Child care was hard to find, because women in those days were expected to give up their professions once they became wives and mothers. Male colleagues often spoke over her, or dismissed her ideas, or diminished her accomplishments.
"I wasn’t alone in that either,” Bell Burnell said. “I knew a number of other women in science who were equally frustrated and concerned."
In 2005, Bell Burnell joined fellow female senior scientists to establish the Athena SWAN award, which is given to institutions that take demonstrable and productive action to address gender inequality.In 2011, Britain's chief medical office announced that medical schools could receive certain government research funding only if they held one of these awards.
Bell Burnell said she was “delighted” to receive the special Breakthrough Prize. But she won't be keeping any of the award money.
“I don’t need a Porsche or Ferrari,” she said. “I don’t have an affluent lifestyle.”
Instead, the funds will go to creating scholarships for women, underrepresented minorities and refugees who want to study physics. The funds will be administered by Britain's Institute of Physics.
"I reckon I discovered pulsars in large part because I was a minority person [at Cambridge]," she said. “And I have a strong suspicion that other minority people might have similar feelings and work equally hard and discover things."