Where is everybody? The great physicist Enrico Fermi first posed the challenging question over half a century ago, wondering why we appear to be alone despite life appearing in the universe. Perhaps the most straightforward answer is that while alien life and even civilizations may be abundant throughout the galaxy, the vast gulfs of time and space that separate us may make us effectively all alone.

Here’s the gist of Fermi’s famous paradox. We know for sure that life, and intelligent species capable of great technological civilizations, has appeared at least once in the universe. The proof: we’re it. But the universe doesn’t tend to do things just once. There isn’t one star, or one galaxy, or one hydrogen atom in the cosmos. When the universe allows something to happen, that thing is almost always ridiculously common, mostly because there’s a whole bunch of universe to allow it.

So if life happened here—once—then it means that life can’t be rare. In other words, Fermi’s argument goes, there’s nothing special about us. So there must be multitudes of lifeforms and intelligent civilizations across every galaxy throughout the universe. And given that the universe has been around for nearly 14 billion years, there has been more than enough time for life to arise, civilizations to develop, and for those aliens to develop the technology needed to completely colonize an entire galaxy. Even if all those civilizations last for only a relatively fleeting amount of time (say, a million years or so), then at least their technological remnants and ruins should be littered anywhere.

And yet, we don’t see anybody. No radio signals from the deep. No signs of alien technology orbiting some distant star. No ruins or remnants to speak of. As far as our observations suggest, we are completely alone.

So what gives? Where is everybody?

Right in front of your nose, idiot. To read more, click here.