The World Without Us

The disk contains 26 selections, including music of pygmies, Navajos, Azerbaijani bagpipes, mariachis, Chuck Berry, Bach, and Louis Armstrong. Lomberg’s most cherished nominee was the Queen of the Night’s aria from Mozart’s The Magic Flute. In it, soprano Edda Moser, backed by the Bavarian State Opera Orchestra, displays the upper limit of the human voice, hitting the loftiest note in the standard operatic repertoire, a high F. Lomberg and the record’s producer, former Rolling Stone editor Timothy Ferris, insisted to Sagan and Frank Drake that it be included.

They quoted Kierkegaard, who had once written: “Mozart enters that small, immortal band whose names, whose works, time will not forget, for they are remembered in eternity.”

With Voyager, they felt honored to make that truer than ever.

The two Voyagers were launched in 1977. Both passed Jupiter in 1979 and reached Saturn two years later. After its sensational discovery of active volcanoes on Jupiter’s moon Io, Voyager 1 dipped below Saturn’s south pole for our first glimpse of its moon Titan, which flipped it out of the solar system’s elliptical plane and off toward interstellar space, actually passing Pioneer 10. It is now farther from Earth than any other human-made object. Voyager 2 took advantage of a rare planetary alignment to visit Uranus and Neptune, and now is also leaving the sun behind.

Lomberg watched the first Voyager launch, with the record’s gilded sleeve bearing his diagrams of its birthplace and what to do with the disk inside—glyphs that he, Sagan, and Drake hoped that any space-navigating intelligence would be able to decipher, though there was little chance it would ever be found, and even less that we would ever know about it. Yet neither the Voyagers nor their recordings are the first manmade entities to travel beyond our planetary neighborhoods. Even after billions of years of relentless space-dust abrasion wears them to dust themselves, there is yet another chance for us to be known beyond our world.

DURING THE 1890s, a Serbian immigrant to America, Nikola Tesla, and an Italian, Guglielmo Marconi, each patented devices capable of sending wireless signals. In 1897, Tesla demonstrated sending ship-to-shore pulses across bodies of water in New York, even as Marconi was doing the same among various British isles—and, in 1901, across the Atlantic. Eventually they sued each other over the claim, and the royalties, to the invention of radio. No matter who was right, by then transmission across seas and continents was routine.

And beyond: Electromagnetic radio waves—waves much longer than poisonous gamma radiation or ultraviolet sunlight—emanate at the speed of light in an expanding sphere. As they move outward, their intensity drops by a factor of one over the distance squared, meaning that at 100 million miles from Earth, the signal strength is one-fourth what it was at 50 million miles. Nevertheless, it is still there. As the sphere of a transmission’s surface expands through the Milky Way, galactic dust absorbs some of the radio radiation, attenuating the signal further. Still, it keeps going.

In 1974, Frank Drake beamed a three-minute radio greeting from the largest radio dish on Earth, the 1,000-foot, half-million-watt Arecibo Radio Telescope in Puerto Rico. The message consisted of a series of binary pulses that an extraterrestrial mathematician might recognize as representing a crude graphical arrangement, depicting the sequence 1 through 10, the hydrogen atom, DNA, our solar system, and a human-shaped stick figure.

The signal, Drake later explained, was about a million times stronger than a typical TV transmission, and was aimed at a star cluster in the constellation Hercules, where it wouldn’t arrive for 22,800 years. Even so, due to the subsequent outcry over possibly having revealed Earth’s whereabouts to superior, predatory alien intelligences, members of the international community of radio astronomers agreed to never unilaterally expose the planet to such a risk again. In 2002, that accord was ignored by Canadian scientists who directed lasers heavenward. But as Drake’s broadcast has yet to elicit a response, let alone an attack, the chance that anything might cross their tight beams can’t be meaningfully computed.

Besides, the cat may long be out of the bag. For more than a half-century, we’ve been sending signals that by now would take a very large or very sensitive receiver to collect—yet, considering the size of the intellect that we imagine might be out there, it’s not impossible.