> He contends that there likely isn't a sentient civilization within about a billion light years of us because the signature of Dyson spheres would be unmistabk

> He contends that there likely isn't a sentient civilization within about a billion light years of us because the signature of Dyson spheres would be unmistabkable and unmissable. Or that making a dyson sphere is harder than FTL, or it isn't economically viable to build one. There's no reason to assume a Dyson sphere would be a logical step after achieving FTL