What to read this week: Emma Chapman’s mind-expanding radio universe

Radio universe
Emma Chapman
John Murray

When he was 16 years old, Albert Einstein imagined himself chasing a beam of light, and as the story goes, this act of imagination helped him develop the now-famous theory of special relativity.

Physicist Emma Chapman also chases the light signal through the known universe and to its very edges in her new book, Radio Universe: How to Explore the Universe Without Leaving Earth (in the US its name is Echoing Universe and is released on May 19). But while Einstein wanted to hop on a beam of light and experience the ultimate speed of space, the light Chapman is talking about is not a carrier but an explorer, a guide and a messenger. “The universe already speaks the language of light,” she writes, and her book offers an amazing insight into how people used radio telescopes to learn and become fluent in that language, too.

As a wave of electromagnetism, light can have many different wavelengths. For example, ultraviolet (UV) light has a relatively short wavelength and its peaks and troughs are much closer together than visible light. Chapman is a radio astronomer, so the light signals he works with are at the opposite end of the electromagnetic spectrum. Radio waves can have adjacent peaks or valleys up to several meters apart.

Because they are so stretched out, radio waves can travel longer distances than any of their electromagnetic relatives, meaning telescopes that either emit or collect them can see and probe deeper into space than other telescopes. Unlike telescopes that collect visible light, radio telescopes can work day and night, saving astronomers time. They’re amazingly versatile machines, Chapman argues, before gleefully chasing their signals from our moon to possible alien space habitats.

Radio universe is organized into three sections – Our Solar System, Our Galaxy and Our Universe – tracing the radio signal’s path to each. For example, in the first chapter, Chapman explores how mankind first touched the moon not with Neil Armstrong’s feet, but rather with a radio wave, as well as how contemporary radio studies play a central role in investigating the origin and history of our satellite.

In the next chapter, we focus on Venus, which is so inhospitable that most light-observation techniques cannot access it – except for radio waves. Their superpower, Chapman says, lies in communicating with an otherwise unrecognizable environment.

In subsequent chapters, he looks at how the most famous images of black holes are based on radio data, how radio astronomers obtained the first indirect evidence of ripples in space-time known as gravitational waves, and how radio waves revealed some of the first exoplanets.

In a chapter on the role radio astronomy can play in the search for extraterrestrial civilizations, Chapman writes, “Radio contact is far more likely than any invasion.” He later adds, “Whether this planet has a yellow-green sky, whether it has five moons, or whether its people have five legs, radio waves will be the form of light used for long-distance communication.”

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The superpower of radio waves is communication with an otherwise unknown environment
“

The last two chapters Radio universe are dedicated to the greatest mysteries of modern physics: dark matter and dark energy. These two substances fill much of our universe, and yet we’re not terribly sure exactly what they are, in part because we don’t know how to detect them directly. Chapman points out all the ways radio telescopes can help, such as by detecting radiation from interstellar hydrogen gas, which allows astronomers to infer exactly where dark matter should be in these regions.

Throughout, Chapman’s writing is accessible, imaginative and compelling. As she described the speed at which Mercury travels around the Sun, making a landing difficult but not deterring investigation via radio signals, I could feel the planet buzzing across my mental map of the solar system.

And when she talked about the asteroid belt, I felt like I was getting a masterclass not only in radio astronomy, but in plain old astronomy—and not by a professor, but by someone who could be a very knowledgeable friend or the absolute best passenger on a long flight. I also laughed at most of Chapman’s jokes and marveled at how her genuine love for her craft as a radio astronomer permeated every page. The book even has an appendix with a list of all the radio telescopes that you can visit as tourists.

It was this great, welcoming and optimistic tone that left me somewhat disappointed when Chapman spoke rather uncritically about the colonization of Mars and the pursuit of commercial lunar exploration. He writes that “a new generation of tech billionaires has ushered in a second space age.” But then she questions whether researchers who want to put their telescopes on the moon will really be welcomed there “among those who wish to mine it, settle on it and use it as a springboard to Mars” – without ever questioning whether this is what the future of space exploration has to be. Shouldn’t an avid astronomer advocate for a more democratic and egalitarian future for space travel and research?

Similarly, while several American and British radio astronomers are examined and highlighted in Chapman’s narrative, much less space and detail is given to researchers from other parts of the world, even though some of the most important radio telescopes were built and operated for years in places such as Puerto Rico and, more recently, Chile.

Ultimately, though, Chapman effectively illustrates a beautiful and powerful point—that our universe is far from silent. “Wherever you are, you are surrounded by radio waves,” he explains. “Some have escaped black holes, some are echoes of asteroids. Some have even traveled to us from the era of the first stars. We just have to close our eyes and listen.”

The next time I find myself under the night sky, even if it is crowded with city lights and the noise of people, I will definitely remember that suggestion to just close my eyes and listen.

Two more great books on astronomy

Fear of the Black Universe: An Unknown Guide to the Future of Physics
by Stepphon Alexander

Here we have a comprehensive narrative of the history and future of our universe from the perspective of an outsider, a dreamer and a musician. Alexander, a working cosmologist and theoretician, does not shy away from drawing inspiration from, for example, experiences at a Zen center he visited in graduate school, or influences such as the artist Jean-Michel Basquiat. This is a book where mathematical tools like Feynman diagrams not only coexist but also cross-pollinate the stories of Alexander’s life as a black man.

The Disordered Cosmos: A Journey into Dark Matter, Space-Time, and Dreams Deferred
by Chanda Prescod-Weinstein

It is a powerful combination of the scientific and the personal The new scientist a columnist who offers both precise details about phenomena like dark matter and insightful analysis of the sociopolitical circumstances that have shaped how we talk about the mysteries of modern physics. Prescod-Weinstein also explicitly addresses the tensions and controversies surrounding where telescopes are built and with whose consent, communicating that scientific rigor can trump activities such as light collection and analysis.

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