“Some molecules - ammonia, carbon dioxide, water - show up everywhere in the universe, whether life is present or not. But others pop up especially in the presence of life itself. Among the biomarkers in Earth's atmosphere are ozone-destroying chlorofluorocarbons from aerosol sprays, vapor from mineral solvents, escaped coolants from refrigerators and air conditioners, and smog from the burning of fossil fuels. No other way to read that list: sure signs of the absence of intelligence.”

American astrophysicist, author, and science communicator

Neil deGrasse Tyson is an American astrophysicist, author, and science communicator. He studied at Harvard University, the University of Texas at Austin, and Columbia University, and has been director of the Hayden Planetarium in New York City since 1996. He was a postdoctoral research associate at Princeton University from 1991 to 1994, then joined the planetarium as a staff scientist and also taught at Princeton as a visiting research scientist and lecturer. At the American Museum of Natural History, he founded the Department of Astrophysics in 1997 and has been a research associate there since 2003.