(Daniel Payne) Radio waves from the last century could have reached 75 different star systems already.
alien civilizations
Oxford Researcher: Humanity Should Look for Star-sized Structures Called “Dyson Spheres” To Find Aliens
(Virgilio Marin) Anders Sandberg of the University of Oxford suggests looking for hypothetical star-sized structures called Dyson spheres to find aliens. He notes that if advanced alien civilizations do exist, they may have built one of these spheres and used it as a supercomputer, solar-capture technology or habitat.