~8.8 Billion Earth Like Planets In This Galaxy Alone

[longship]

10. Yup, the Fermi paradox.

Fermi paradox.

As it is usually told, I find it amusing that when Enrico Fermi asked "where is everybody?" his luncheon compatriots knew what he was asking.

It is a great question but I don't think we know enough to provide a reasonable answer. The standard answer is that the distance between intelligent life forms in the galaxy (even if it is common) is so large that they are all relatively isolated in their respective planetary systems. Interstellar travel may be that difficult.

Of course, Fermi pointed out that it would only take a few millions of years to accomplish galactic colonization, small when compared to the billions of years the galaxy has existed.

I like mathematician Ian Stewart's answer. Maybe the galaxy is full of intelligent life, but they are all independently thinking of the Fermi paradox and are not venturing out themselves. They are all just sitting around wondering, "Where is everybody?"

That's my favorite answer. It has a Douglas Adams element to it.