Humanity is on the threshold of being able to detect signs of alien life on other worlds.
By studying exoplanet atmospheres, we can look for gases like oxygen and methane that only coexist if replenished by life. But those gases come from simple life forms like microbes. What about advanced civilizations? Would they leave any detectable signs?
They might, if they spew industrial pollution into the atmosphere. New research by theorists at the Harvard-Smithsonian Center for Astrophysics (CfA)