What to read this week: Emma Chapman’s mind-expanding Radio Universe

Radio Universe
Emma Chapman
John Murray

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

Physicist Emma Chapman also chases a light signal through the known universe and all the way to its edges in her new book, Radio Universe: How to explore space without leaving Earth (in the US its title is The reverberating universe and comes out on May 19). But while Einstein wanted to ride the beam of light and experience the fastest speed of space, the light Chapman seeks plays the role not of a carrier but of an explorer, a guide and a messenger. “The universe already speaks the language of light,” she writes, and her book offers great insight into how humans have used radio telescopes to learn and master that language as well.

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 those of 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 several meters apart.

Because they are so stretched out, radio waves can travel greater distances than any of their electromagnetic cousins, meaning telescopes that emit or collect them can see and probe deeper into space than other telescopes. Unlike telescopes that collect visible light, radio telescopes can operate both at night and during the day, buying astronomers extra time. They are amazingly versatile machines, Chapman asserts, before happily chasing their signals from our moon to possible space dwellings of aliens.

Radio Universe is organized into three sections – Our Solar System, Our Galaxy and Our Universe – following the journey of a radio signal to each. For example, in the first chapter, Chapman explores how the first time mankind touched the moon was not by Neil Armstrong’s feet, but rather by radio wave, and how modern radio research plays a central role in the study of the origin and history of our moon.

Another chapter focuses on Venus, which is so inhospitable that most light-based observation techniques cannot access it – except for radio waves. Their superpower, Chapman says, is communicating with otherwise unknowable environments.

In later chapters, she examines how the most famous images of black holes were based on radio data, how the first indirect evidence of ripples in space-time, known as gravitational waves, was obtained by radio astronomers, and how radio waves revealed some of the first exoplanets.

In the chapter on the role that radio astronomy can play in the search for extraterrestrial civilizations, Chapman writes, “Far more likely than any invasion is contact by radio signal.” She 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 that is used for long-distance communication.”

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The superpower of radio waves is communication with otherwise unknowable environments
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The last two chapters of Radio Universe are devoted to the greatest mysteries of modern physics: dark matter and dark energy. These two substances fill much of our cosmos, and yet we’re not very sure exactly what they are, in part because we don’t know how to directly detect them. 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 in these regions dark matter should be.

Throughout, Chapman’s writing is accessible, imaginative and compelling. When she described the speed at which Mercury orbits the sun, which makes landing on it difficult but does not interfere with radio-signal studies, I felt the planet buzzing in my mental map of the solar system.

And when she discussed the asteroid belt, I felt like I was getting a masterclass not only in radio astronomy, but in plain old astronomy—and not from a professor, but from someone who could be a very experienced friend or the best seatmate 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 permeates every page. The book even has an appendix listing all the radio telescopes you can visit as a tourist.

It was this great, inviting and optimistic tone that made me somewhat disappointed when Chapman discussed, rather uncritically, the colonization of Mars and efforts to commercially explore the moon. She writes that “a new generation of tech billionaires has ushered in a second space age.” But then she asks whether researchers who want to put their telescopes on the moon will actually be welcome there “among those willing to mine it, settle on it, and use it as a springboard to Mars” — without ever questioning whether the future of space exploration should absolutely be that way. Shouldn’t an ardent astronomer advocate for a much more democratic and egalitarian future for space travel and exploration?

Likewise, while several American and British radio astronomers are vetted and highlighted in Chapman’s account, there is much less space and detail devoted 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 like Puerto Rico and, more recently, Chile.

Ultimately, however, Chapman is effective in illustrating a beautiful and powerful point—that our universe is far from quiet. “Wherever you are, you are surrounded by radio waves,” she explains. “Some have escaped from black holes, some are echoes from asteroids. Some have even traveled to us from the age of the first stars. We just have to close our eyes and listen.”

The next time I find myself under a night sky, even if it’s crowded with city lights and the noise of people, I’ll be sure to remember this suggestion to just close my eyes and listen.

Two more great astronomy books

Fear of a Black Universe: An Outsider’s Guide to the Future of Physics
by Stefan Alexander

Here we have a complex telling of the history and future of our universe from the perspective of an outsider, a dreamer and a musician. Alexander, a working cosmologist and theorist, is not shy about drawing inspiration from, for example, experiences at a Zen center he visited in graduate school, or influences such as the painter Jean-Michel Basquiat. This is a book in which mathematical tools such as Feynman diagrams not only coexist but cross-pollinate with stories from Alexander’s life as a black man.

The Disturbed 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 A new scientist columnist offering both rigorous detail on phenomena like dark matter and thoughtful analysis of the socio-political circumstances that have shaped the way we talk about the mysteries of modern physics. Notably, Prescod-Weinstein also explicitly addresses the tensions and controversies surrounding where telescopes are built and with whose consent, conveying that scientific rigor can go beyond activities such as collecting and analyzing light.

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