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

Radio Universe
Emma Chapman
John Murray

At the age of 16, Albert Einstein imagined 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 to its far reaches in her new book, Radio Universe: How to explore space without leaving Earth (in the United States its title is The universe echoes and it comes out on May 19). But while Einstein wanted to jump on the light beam and experience the fastest speed in the cosmos, the light that Chapman is looking for plays not the role of carrier, but of explorer, guide and messenger. “The universe already speaks the language of light,” she writes, and her book offers a wonderful insight into how humans have used radio telescopes to learn and master this language as well.

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

Because they are so widespread, radio waves can travel longer distances than any of their electromagnetic relatives, meaning that the telescopes that emit or collect them can see and probe deeper into the cosmos than other telescopes. Unlike telescopes that collect visible light, radio telescopes can operate night or day, saving astronomers time. They are surprisingly versatile machines, says Chapman, before happily chasing their signals from our moon to the possible cosmic homes of extraterrestrials.

Radio Universe is organized into three sections – Our Solar System, Our Galaxy and Our Universe – following the journey of a radio signal to each of them. For example, in the first chapter, Chapman explores how the first time humanity touched the moon was not via Neil Armstrong’s foot, but rather with a radio wave, as well as how contemporary radio studies plays a central role in studying the origin and history of our satellite.

In another chapter, the focus is on Venus, which is so inhospitable that most light-based observing techniques cannot access it except radio waves. Their superpower, says Chapman, is to communicate with otherwise unfamiliar environments.

In subsequent chapters, she explains how the most famous images of black holes are 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 discovered some of the first exoplanets.

In the chapter on the role that radio astronomy can play in the search for extraterrestrial civilizations, Chapman writes: “Contact by radio signal is far more likely than any invasion. ” Later, she adds: “Whether this planet has a yellow-green sky, whether it has five moons, or whether its inhabitants have five legs, radio waves will be the form of light used for long-distance communications. »

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 are completely unsure of what exactly they are, in part because we don’t know how to detect them directly. Chapman points out all the ways radio telescopes can help, for example by detecting radiation from interstellar hydrogen gas, which allows astronomers to infer exactly where dark matter should be found in these areas.

Throughout, Chapman’s writing is accessible, imaginative and compelling. When she described the speed at which Mercury moves around the sun, making landing difficult but not deterring investigation via radio signals, I felt the planet buzzing through my mental map of the solar system.

And when she talked about the asteroid belt, I felt like I was taking a master class not only in radio astronomy, but also in classical astronomy – and not from a professor, but from someone who might be a very knowledgeable friend or the best seatmate on a long flight. I also laughed at most of Chapman’s jokes and marveled at how his sincere love for his profession as a radio astronomer permeated every page. The book even has an appendix listing all the radio telescopes you can visit as a tourist.

It was this grand, inviting, optimistic tone that later disappointed me somewhat when Chapman spoke, uncritically, about the colonization of Mars and efforts at commercial exploration of the Moon. She writes that “a new generation of tech billionaires has unleashed a second space age.” But then she wonders whether researchers who want to put their telescopes on the Moon will really be welcome there “among those who want to exploit it, settle there and use it as a springboard to Mars” – without ever asking whether the future of space exploration absolutely must be like this. Shouldn’t an ardent astronomer advocate for a much more democratic and egalitarian future for cosmic travel and research?

Likewise, while several American and British radio astronomers are cited and highlighted in Chapman’s account, much less space and detail is devoted to researchers in 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 succeeds in illustrating a beautiful and powerful point: our universe is far from calm. “Wherever you are, you are surrounded by radio waves,” she explains. “Some escaped black holes, others are echoes of asteroids. Some even came to us from the era of the first stars. Just close your eyes and listen.”

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

Two other great books on astronomy

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

Here we have a complex account of the history and future of our universe from the perspective of an alien, a dreamer, and a musician. Alexander, an active cosmologist and theorist, does not hesitate to draw inspiration, for example, from experiences in a Zen center he visited during his higher studies, or from influences such as the artist Jean-Michel Basquiat. This is a book in which mathematical tools, such as Feynman diagrams, not only coexist but also cross-fertilize with 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 blend of scientific and personal aspects of New scientist columnist, offering both rigorous detail on phenomena, such as dark matter, and meaningful analysis of the sociopolitical circumstances that have shaped the way we talk about the mysteries of modern physics. Notably, Prescod-Weinstein also explicitly addresses tensions and controversies regarding where telescopes are built and with whose consent, indicating that scientific rigor can transcend activities such as light collection and analysis.