THE ECHOING UNIVERSE

The joys of radio astronomy.

British astrophysicist Chapman, author of First Light: Switching on Stars at the Dawn of Time (2020), emphasizes that while 400 years of magnifying light with telescopes produced spectacular discoveries, there are other ways of examining stars. Human eyes see only a minuscule fraction of a huge spectrum that ranges from tiny gamma rays and X-rays to long microwaves and immensely long radio waves. Discovered in the 1880s, radio waves proved useful in communication because they aren’t stopped by clouds, rain, or even buildings. By the 1930s, engineers noticed an annoying hiss that accompanied all radio transmissions. A few amateurs claimed that this came from stars, but it took decades before engineers—and astronomers—believed them. Energized by World War II technology (radar also uses radio waves), radio astronomy entered the mainstream during the 1950s. Unlike familiar instruments, radio telescopes operate 24 hours a day in all weather and don’t require protective domes. Chapman reminds readers that radio telescopes transmit as well as receive. Venus hides under a dense atmosphere, but bouncing radio waves off its surface produced a map and determined the length of its day. In sprightly prose, the author takes up the great questions of cosmology. Writing about the origin of the universe, she observes, “The Big Bang. It couldn’t sound more dramatic if it tried, could it? Those three syllables encapsulate an idea so mind-boggling it defies intuition: that everything, the entire contents of the Universe was once condensed into a point of effectively infinite density.” And then there is the “haunting presence” of dark energy, “a mysterious force driving the accelerated expansion of the Universe….If dark energy gets stronger, it could speed up the expansion so much that galaxies, then stars, and then even atoms are torn apart in a Big Rip….Cheery, eh?”

A cogent and lively introduction to unseen forces in the universe.