Its actually kind of scary if we’re the only ones out there. It might mean that we’re destined to destroy ourselves soon, and they’ll be no one for us to learn from. Sure we would have ample reason to be afraid if we found an alien civilization that was far in advance of us, spanning multiple star systems, but at least than we would know that humans could survive to become a space fairing species.
Anyway, I’m no scientist, and I probably know far less about this than the guy who wrote the scientific American article, but it seems to me, that we really can’t know right now if there aren’t any large scale alien civilizations out there right now, even if we haven’t detected them. At this very moment on the other side of the milky way galaxy, an advanced alien civilization could be constructing its first Dyson sphere’s and we would have no way to detect them since even light doesn’t travel fast enough for it to reach us within the lifetime of anyone alive on the planet today. Even our great, great, great, great, great grandchildren will all be dead long before the light currently on the other side of the Milky way reaches us, and that’s just our galaxy. I don’t know, maybe even the oldest large scale alien civilization is too recent and too far away for us to be able to detect them right now.