When astronomy writer Christopher Crockett describes what a fast radio burst is like, he offers a whistle that swoops in pitch from high to low. “If you could hear the signal, that’s what it would sound like,” he says. He is quick to explain, though, that the eight mysterious pulses detected by two radio telescopes are actually not sounds at all. Fast radio bursts are light waves in the radio frequency range of the electromagnetic spectrum that appear to have journeyed from other galaxies. And, as Crockett explores in his story "Searching for distant signals," these unexplained signals may be trying to tell us something.
The entire history of astronomy can be viewed as humans trying to decipher enigmatic messages from space. Go back to the Greeks, who watched the heavens and saw a fixed pattern of stars slowly turning around the night sky. They interpreted that observation to mean that the stars are attached to a large sphere that rotates around the Earth (and not, as turns out to be true, that Earth itself is spinning). But that was through no fault of the stars. The Greeks also noticed the out-of-sync movement of a few stars and named them the “wanderers.” When correctly decoded, that was the universe telling us about the planets. Much later, scientists saw that some stars appeared out of nowhere or got dramatically brighter. Those signals revealed the existence of supernovas. Fuzzy stars eventually resolved into the forms of galaxies in all manner of shapes and sizes. Much more recently, astronomers learned to interpret strange bursts of gamma rays as signs of explosive cataclysms far, far away — a lesson that’s expected to prove useful for astronomers seeking to understand fast radio bursts.
Yet to be deciphered, these signals represent the latest messages from space with the potential to tell us more about the cosmos. It’s part of a continuing story of discovery, another clue in the ultimate mystery. What’s out there making all that racket? Searching for answers has already invigorated the imagination of scientists, and I expect the possibilities they’ve suggested will spark your imagination as they have mine.