Are aliens building gigantic power plants in space that make entire stars "disappear"? Two studies find dozens of stars with such bizarre emissions that the researchers have come up with a bold hypothesis ... . Dyson spheres are used by higher civilizations to generate energy. These fantastic species can theoretically tap into the energy of the entire universe and thus secure infinite energy reserves. What happens when we find such spheres? Is this the first contact with civilizations that are far superior to us?