The Fermi Paradox explained

[blatherskite]

The Fermi paradox (loosely, "if the universe is so old, why aren't there more civilizations of intelligent aliens out there?") has many explanations. My personal explanation is that even if we could recognize (say) a radio signal from another star, the odds of deciphering its message without any context are slim to none. (Think of the barriers that faced Egyptologists until the "Rosetta Stone" was discovered if you want an idea of the magnitude of the problem. And that's for a human language. A truly alien language will be an order of magnitude more difficult to translate.) The footnote to that is that most societies won't bother spending the money to scan the heavens for signs of life, which drastically decreases the number of civilizations that are detectable in the first place.

Of course, the ever-reliable XKCD has a better explanation.

Could be.