It was 1967.
The University of Cambridge, a beacon of knowledge in England, became the stage for a groundbreaking exploration into the origins of the universe. Scientists were determined to trace the faint whispers of the first stars born in the cosmos. To achieve this, a series of radio telescopes was meticulously arranged across the university’s expansive fields.
These telescopes, designed to capture faint whispers of radio signals from distant stars. This array of radio telescopes is formally known as a “radio interferometer.” This marvel of engineering, with its row upon row of interconnected instruments, worked as a single, unified system. Together, they captured the cosmic echoes emitted by celestial objects, offering glimpses into the universe’s earliest chapters.
The beauty of a radio interferometer lies in its ingenious ability to overcome the limitations of a single radio telescope. Imagine two buckets of equal height but with different mouth sizes. The smaller bucket fills up with water faster, while the larger one takes longer to fill. Similarly, a larger radio telescope dish can capture more signals, but there’s a catch—making a dish larger isn’t limitless. At a certain size, the dish becomes so heavy that it collapses under its own weight.
Faced with this challenge, scientists came up with a groundbreaking solution. Instead of building one gigantic dish, they used multiple smaller ones. Picture this: collecting rainwater in several small buckets and then combining it all into one large container. Similarly, signals from multiple radio telescopes are gathered individually and then merged into a single, unified stream. This sophisticated system, where several telescopes work together as one, is known as a “radio interferometer.”
At Cambridge University, researchers were at the forefront of this innovation. Their carefully constructed interferometer became a cosmic detective, piecing together faint radio signals to uncover the secrets of stars born at the dawn of the universe. With every signal captured, they inched closer to unraveling the mysteries of the cosmos, bridging the gap between our world and the stars.
The Beginning of Jocelyn Bell’s Journey
Every year, scientists at the University of Cambridge select a group of students to work on PhD research projects. The students carry out research, guided and supported by the scientists who help them navigate various tasks.
In 1967, a young woman with an impressively long name—Dame Susan Jocelyn Bell Burnell—applied for a PhD at Cambridge. However, everyone simply called her Jocelyn Bell. Jocelyn was particularly intrigued by a mysterious cosmic phenomenon known as quasars, which were a major focus of ongoing research at the university. Even today, quasars remain a subject of mystery, with much about them still unknown.
At the time, the project to discover quasars using Cambridge’s radio interferometer was led by the eminent astronomer Dr. Martin Ryle. Since this was a topic Jocelyn was deeply passionate about, she approached Dr. Ryle to express her interest. After careful evaluation, Dr. Ryle decided to place his trust in her abilities. Jocelyn Bell was accepted as a PhD student at Cambridge, with none other than the renowned astronomer Anthony Hewish serving as her supervisor.
Jocelyn Bell’s journey to greatness was not without its hurdles. Her school authorities decided she would not be allowed to study science. The reason? She was a girl. In the school’s view, girls were meant to learn “sewing and household skills,” not science. This unfair decision left Jocelyn heartbroken, as it threatened to crush her dream of becoming an astronomer.
Refusing to give up, Jocelyn turned to her parents for help. Outraged by the school’s blatant discrimination, her parents took a stand. They challenged the decision in court, determined to secure their daughter’s right to study science. Victory was theirs, and with it, Jocelyn’s path to the stars reopened.
Growing up in a home filled with books—thanks to her parents’ love for knowledge—Jocelyn often spent hours exploring their library. One day, she discovered a book that would change her life: “Frontiers of Astronomy” by the legendary Fred Hoyle. Inside, she found an introductory chapter on radio astronomy that completely captivated her. The young Jocelyn was so inspired that she made a decision on the spot: one day, she would become a radio astronomer. This determination, sparked by her family’s unwavering support and her own curiosity, set the stage for one of the most remarkable journeys in the history of science.
As a PhD student at Cambridge, Jocelyn Bell often found herself overwhelmed by a sense of disbelief. She couldn’t shake the feeling that she wasn’t supposed to be there. How had she managed to secure a place at such a prestigious institution? Jocelyn convinced herself that it must have been a mistake on the university’s part, a clerical error that had somehow allowed her to slip through the cracks.
Convinced that the university would one day discover their “mistake” and expel her, Jocelyn decided to take matters into her own hands. She resolved to work harder than anyone else. Her goal was clear: to become so invaluable through her dedication and achievements that, even if her presence at Cambridge was questioned, her contributions would compel them to let her stay.
Fueled by this fear and determination, Jocelyn poured herself into her work, navigating each day with an unrelenting drive to prove her worth. This mindset, born of self-doubt, became the foundation of the extraordinary legacy she would go on to build.
Signals from the farthest corners of the universe traveled millions of light-years to reach Cambridge University’s radio interferometer. There, they were captured and printed onto sprawling chart papers. Yet, not every signal was a message from the cosmos. Some were ordinary—like signals from telephone conversations—and others were Earthly phenomena, such as the radio waves generated by lightning strikes.
Jocelyn Bell’s role was as thrilling as it was meticulous. Like a modern-day Sherlock Holmes, she pored over the charts with unwavering focus, deciphering which signals hailed from the mysteries of space and which were mere noise from human activity. This wasn’t a task for the faint-hearted—it required razor-sharp concentration and an almost intuitive understanding of the universe’s patterns.
Every day, Jocelyn tackled an immense challenge: analyzing 100 feet of chart paper. To put that into perspective, it’s roughly the height of a nine-story building. With each line, blip, and curve she examined, she was inching closer to uncovering the secrets of the cosmos. Her relentless dedication transformed an otherwise daunting task into the foundation of one of the most groundbreaking discoveries in astrophysics.
Among the vast sea of signals captured by the radio interferometer, not all were messages from the cosmos. Many were unwanted disruptions—radio noise generated by human activities. While modern-day computers can easily filter out such noise, Jocelyn Bell and her fellow PhD students were given a different directive by Antony Hewish. He insisted they analyze the signals manually, as programming could sometimes erase weak but significant signals. Additionally, manual observation trained their eyes to distinguish between human-made noise and authentic cosmic whispers.
For Jocelyn, this meant hours upon hours of painstaking work. Armed with a magnifying glass, she scrutinized every line and blip on the chart paper, searching for patterns that might reveal their origin. Many nights were spent sleepless, her relentless dedication fueled by a determination to leave no detail unnoticed. After exhausting analysis, she would compile her findings into detailed reports, each one a testament to her hard work and precision.
This grueling process wasn’t just about analyzing data—it was about mastering the art of seeing what others might miss. In those quiet, tireless hours, Jocelyn Bell laid the foundation for discoveries that would forever change our understanding of the universe.
The Mysterious Pulse
It was a quiet night in 1967. Jocelyn Bell sat amidst a sea of signal charts in her dimly lit room, a steaming mug of coffee in hand. The charts, filled with traces of signals captured by the radio interferometer, held the whispers of the cosmos. Night after night, Jocelyn meticulously analyzed these signals, a task that had turned her into an expert at identifying the difference between the hum of distant stars and the static of a neighbor’s radio.
As she moved closer to a stack of charts, her sharp eyes caught something unusual. One particular signal stood out. The periodic spikes on the chart were unlike anything she’d seen before—strange and intriguing. Curious, she picked up the chart, examining it with the precision of someone who understood the language of the universe.
The signal seemed to originate from a distant star, but its rapid periodicity puzzled her. Why were the intervals so short? What could produce such a distinct, rhythmic pattern? Questions filled her mind, and in that moment, Jocelyn knew she had stumbled upon something extraordinary—a mystery waiting to be unraveled.
Jocelyn Bell noticed—a signal arriving precisely every 1.33 seconds, as steady as a heartbeat. It was as if someone stood on a distant hilltop, flashing a light directly at her at perfect intervals. But in this case, it wasn’t light; it was a radio signal.
The precision of the pulses left her intrigued and puzzled. Who, or what, could be out there on a distant star, sending such rhythmic signals toward Earth every 1.33 seconds? Jocelyn wrestled with the mystery, unable to find a logical explanation. It was a cosmic riddle unlike anything she had encountered before.
The moment Jocelyn Bell detected the strange signals, she picked up the phone and called her PhD supervisor, Antony Hewish. She explained that she had come across something unusual—signals that defied explanation. Dr. Hewish, skeptical, brushed it off, assuming she must have misconnected some wires. “That’s probably why you’re getting these odd signals,” he said confidently.
However, when Dr. Hewish examined the signals himself the next day, he shifted his stance slightly but still dismissed their significance. “These are nothing unusual,” he said. “They’re likely interference from telephone lines or some man-made radio source. Don’t waste too much time on this.”
But Jocelyn wasn’t convinced. She had spent countless hours analyzing charts, and her instincts told her these signals weren’t from any human-made source. She pressed the issue, trying to explain her reasoning. Finally, Dr. Hewish asked sarcastically, “Fine, if they’re not human-made, who sent them? Aliens? Little green men?”
Jocelyn knew the idea of extraterrestrial life could explain the signals, but she also understood the risks. Bringing up aliens in a scientific discussion could jeopardize her credibility and reduce the discovery to a joke. Determined to avoid ridicule, she chose to stay silent, letting the mystery linger until the evidence could speak for itself.
Discovery of The Little Green Men
The Winter Discovery: Jocelyn Bell’s Mysterious Pulses
While winter brought holidays to the world, the stars remained ever active. Astronomers, too, were undeterred by the cold, continuing their relentless study of the cosmos. Among them was Jocelyn Bell, tirelessly monitoring the skies late into the frosty nights. The biting cold had caused some of the radio receivers to freeze, and Jocelyn improvised, warming them with her breath to restore functionality.
But then, something astonishing happened—the strange pulse signals reappeared. This time, they came from a different region of the sky, with a new period of 1.2 seconds. Jocelyn pondered, If the previous signal was alien-made, then perhaps this one is too. Yet, a nagging question lingered: how could two alien civilizations, from opposite corners of the universe, settle on the exact same frequency to communicate? And why would they both target Earth?
Dismissing the alien theory, Jocelyn considered a more plausible explanation. Perhaps these were signals from a type of star yet to be discovered, something unknown to human science. She immediately called her supervisor, Dr. Antony Hewish, to report her findings. This time, even Dr. Hewish couldn’t ignore the patterns. The presence of two celestial objects with such synchronized pulses demanded attention.
However, they faced a dilemma: how could they present this mystery to the scientific community without definitive proof? Acknowledging the risks of ridicule, they decided to tread carefully. For now, they humorously referred to these enigmatic objects as “Little Green Men”—a lighthearted nod to the possibility of extraterrestrial origins.
And thus, a playful nickname marked the beginning of a discovery that would forever change our understanding of the universe.
The Unveiling of Pulsars
In a crucial moment of astronomical discovery, astronomer John Pilkington analyzed the dispersion measurements of strange radio signals and concluded that they were coming from beyond our solar system. The realization was clear: these signals couldn’t possibly be of human origin. Yet, despite the mystery surrounding them, neither Dr. Hewish nor Jocelyn Bell could find a satisfying explanation. Determined to get to the bottom of it, they decided to call a meeting in Cambridge to discuss the perplexing signals.
The meeting brought together a group of distinguished astronomers, all eager to hear Dr. Hewish’s account of the discovery. Among the attendees was Dr. Fred Hoyle, the scientist whose book had inspired young Jocelyn Bell to become a radio astronomer. After listening intently to Dr. Hewish, Dr. Hoyle offered a theory that immediately struck a chord. He suggested that if the signals were coming from the magnetic poles of a neutron star, they would behave much like a lighthouse. When one magnetic pole faced the telescope, a signal would be detected; when it turned away, there would be silence. Given that pulsars are capable of spinning at extraordinary speeds, this could explain the unusual regularity of the signals.
What followed was a revelation: the two mysterious objects Jocelyn Bell had discovered were, in fact, pulsars. Even before fully grasping their physics, Bell had inadvertently uncovered two of these enigmatic celestial objects, forever altering the course of astronomical research.
The Nobel Prize for Pulsar Discovery
The discovery of the pulsar captured the imagination of the public. Here was an extraordinary object that could rotate on its axis once every 1.33 seconds. Imagine standing on this pulsar, orbiting our Sun—blink and it would be day, blink again and it would be night. Its speed was nothing short of astonishing.
Given the magnitude of this discovery, many believed Jocelyn Bell deserved the Nobel Prize for her groundbreaking work. However, the prestigious honor was awarded to Dr. Martin Ryle and Dr. Antony Hewish instead. Why was Jocelyn Bell, the very scientist who made the pulsar discovery, left out?
Dr. Hewish explained the rationale, saying,
“The captain of a ship is the key. The captain guides the ship to its destination. Even if a crew member spots an island and informs everyone, the crew member’s role in reaching the destination is secondary.”
This reasoning overshadowed Bell’s monumental achievement, despite her central role in the discovery.
Jocelyn Bell, a PhD student at the time of her groundbreaking discovery, was notably not awarded the Nobel Prize for her work. While many argued that her status as a PhD student was the reason, others speculated that her gender played a more significant role. In an era when the idea of a woman making such a monumental scientific breakthrough was difficult for many to accept, Bell faced considerable societal bias. However, Bell herself never voiced any complaints about the situation. Instead, she humbly remarked that awarding a Nobel Prize to a PhD student for anything less than an extraordinary, rare discovery would diminish the value of the prize. To her, the pulsar discovery wasn’t an extraordinary stroke of luck; it was merely an unexpected accident of science.
The injustice didn’t go unnoticed by others. One of her most vocal critics was Fred Hoyle, the renowned astronomer and Bell’s childhood role model. While the scientific community failed to properly credit Bell, they mistakenly attributed the discovery to Dr. Antony Hewish. The pain of this situation lies not only in the oversight but in the fact that because Bell was a woman, her achievement was claimed by someone else. The media further perpetuated this injustice, belittling her accomplishments due to her gender.
Despite the harsh criticisms and the prejudice she faced, Jocelyn Bell remained unwavering in her pursuit of knowledge. She continued her work in astronomy, making significant contributions to X-ray astronomy. Over time, Bell’s rightful place in history as the true discoverer of the pulsar was recognized. Her pioneering work eventually earned her the prestigious Breakthrough Prize, a well-deserved recognition for the woman who had been instrumental in one of the most important astronomical discoveries of the 20th century.
References:
- For the research paper on the pulsar discovered by Jocelyn Bell and the associated dispersion measurements (which are discussed in the next chapter), see:
Hewish, A., Bell, S. J., Pilkington, J. D., Scott, P. F., & Collins, R. A. (2013). Observation of a Rapidly Pulsating Radio Source. In A Source Book in Astronomy and Astrophysics, 1900–1975 (pp. 498-504). Harvard University Press. - To read Jocelyn Bell’s own comments on not receiving the Nobel Prize, see:
Bell Burnell, S. J. (1979). Little Green Men, White Dwarfs or Pulsars?. Cosmic Search, 1(1), 16. - For more details on pulsars, see the following chapter:
Verschuur, G. (2015). Pulsars. In The Invisible Universe: The Story of Radio Astronomy. Springer.
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