Hitting the Books: The first man to listen to the birth of the stars

If the efforts of the more than 10,000 people who developed and assembled the James Webb Space Telescope are any indication, the age of the independent scientist is well over. Newton, Galileo, Keppler, and Copernicus all fundamentally changed humanity’s understanding of our place in the universe and did so on their own, but with the formalization and professionalization of the field in the Victorian era, these instances were of an amateur astronomer using home-brewed equipment. so much more rarely.

In his new book, The invisible world: why there is more to reality than meets the eye, University of Cambridge Public Astronomer, Matthew Bothwell, tells the story of how we discovered an entire, unprecedented universe beyond the natural vision of humanity. In the excerpt below, Bothwell talks about the exploits of the Grote Rebers, one of the world’s first (and for a time only) radio astronomers.

The Invisible Universe by Matthew Bothwell published by Oneworld

Oneworld Publishing

Excerpts with permission from The Invisible Universe by Matthew Bothwell (A world 2021).


The only radio astronomer in the world

It’s a little strange to look back at how the astronomical world reacted to Jansky’s results. In retrospect, we can see that astronomy was being turned upside down by a revolution at least as big as the one launched by Galileo’s telescope. Discovering radio waves from space marks the first time in history that humanity glimpsed the vast invisible universe that hid beyond the narrow window of the visible spectrum. It was a significant event that was almost ignored in academic astronomy circles for a very simple reason: the world of radio technology was just too far away from the world of astronomy. When Jansky published his first results, he tried to bridge the gap by using half of the paper to give his readers a crash course in astronomy (explain how to measure the location of things in the sky, and exactly why a signal is repeated every 23 hour and 56 minutes meant something interesting). But in the end, the two disciplines suffered from a lack of communication. The engineers spoke a language of vacuum tubes, amplifiers, and antenna voltages: incomprehensible to scientists more accustomed to talking about stars, galaxies, and planets. As Princeton astronomer Melvin Skellett later put it:

The astronomers said “Well that’s interesting – you mean, there’s radio stuff coming from the stars?” I said, ‘Well, that’s what it looks like’. ‘Very interesting.’ And that was all they had to say about it. Everything from Bell Labs they had to believe in, but they saw no need for it or any reason to investigate further. It was so far from the way they thought of astronomy that there was no real interest.

After Jansky had moved on to other issues, only one person became interested in listening to radio waves from space. For about a decade, from the mid-1930s to the mid-1940s, Grote Reber was the only radio astronomer in the world.

The history of the Grote Reber is unique throughout the science of the twentieth century. He developed on his own an entire field of science, taking on the task of building equipment, making observations, and exploring the theory behind his discoveries. What makes him unique is that he did all this as a complete amateur, working alone outside the scientific establishment. His job, designing electrical equipment for radio broadcasts, had given him the skills to build his telescope. His fascination with the scientific literature brought him into contact with Jansky’s discovery of cosmic statics, and when it became clear that no one else in the world seemed to care much, he undertook to invent the field of radio astronomy. He built his telescope in his backyard in Chicago using equipment and materials available to anyone. His telescope, almost ten meters across, spoke in his neighborhood (with good reason – it looks a bit like a cartoon doomsday device). His mother used it to dry her laundry.

He spent years scanning the sky with his homemade machine. He observed with his telescope all night, every night, while still working on his daily work (apparently he snatched a few hours of sleep in the evening after work, and again at dawn, after finishing at the telescope). When he realized he did not know enough physics and astronomy to understand the things he saw, he took courses at the local university. Over the years, his observations painted a beautiful picture of the sky seen through radio eyes. He discovered the sweep of our Milky Way, with bright spots in the galactic center (where Jansky had captured his star static), and again towards the constellations Cygnus and Cassiopeia. By this time, he had learned enough physics to also make scientific contributions. He knew that if the hiss from the Milky Way was caused by thermal emission – heat radiation from stars or hot gas – then it would be stronger at shorter wavelengths. Considering that Reber captured much shorter wavelengths than Jansky (60 cm, compared to Jansky’s fifteen meter long waves), Reber should have been bombarded with invisible radio waves tens of thousands of times more powerful than anything Jansky saw. But he was not. Reber was confident enough in his equipment to conclude that no matter what made these radio waves, it had to be ‘non-thermal’ – that is, it was something other than the standard ‘hot things glow’ radiation we discussed back in Chapter 2. He even suggested the (correct!) solution: that hot interstellar electrons whizzing past an ion – a positively charged atom – would be tossed around like a Formula 1 car taking a narrow turn. The oscillating electron will emit a radio wave, and the combined effect of billions of these events is what Reber discovered from his backyard. This only happens in clouds of hot gas. It turns out that Reber intercepted radio waves emitted by clouds containing newborn stars scattered across our galaxy. He literally listened to stars being born. It was a sound that no human had ever heard before. To this day, radio observations are used to track the formation of stars, from small clouds in our own Milky Way to the birth of galaxies in the farthest corners of the universe.

In many ways, Reber’s story seems like an anachronism. The golden age of independent scientists who could make groundbreaking discoveries by working alone with homemade equipment was hundreds of years ago. After the Victorian era passed, science became a complex, expensive and above all professional enterprise. Grote Reber is, as far as I know, the last of the amateur “outsider” scientists; the last person, who had no scientific education, built his own equipment in his garden, and through painstaking and meticulous work managed to change the scientific world.

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