Time: 1950
Place: Los Alamos National Laboratory
A lunch meeting including Edward Teller (father of the nuclear bomb) and the Nobel Prize-winning Enrico Fermi.
Topic of Discussion: recent UFO sightings

Fermi suddenly asks, “Where is everybody?”

If the universe is full of intelligent technological civilizations, why haven’t they already made it to Earth?

His question, now known as “Fermi’s paradox,” is one still frequently asked in astrobiological and SETI discussions. (I have also heard it asked about time travelers.)

Astrophysics professor Adam Frank says about on the 13.7 blog, that “the most important thing to understand about Fermi’s paradox is that you don’t need faster-than-light travel, a warp drive or other exotic technology to take it seriously. Even if a technological civilization built ships that reached only a fraction of the speed of light, we might still expect all the stars (and the planets) to be ‘colonized.’ ”

The calculations take a lot of the fun out of imagining visits from friendly and helpful aliens.

Take just one high-tech alien species sending ships out at one-hundredth of the speed of light. It would take a few centuries to a millennium to get to a new solar system. Then they use its resources to build more ships and colonization spreads. To make it from one end of our Milky Way to the other would take just 10 million years. Just.

Sounds like a long time, but not compared to the 10-billion-year-old Milky Way.

Throw in the use of some kind of cryogenic suspension or “generation ships” (mobile worlds whose inhabitants live out entire lives during the travel) and it seems possible.

Adam Frank also offers some simple resolutions to Fermi’s paradox:

Maybe the aliens don’t want to colonize other worlds.

Maybe no one, even the advanced aliens, has the technologies for these journeys.

Or the saddest one: The aliens aren’t here because they don’t exist. We are the only sentient, technological species that exists in the entire galaxy.

I still want to believe.

i want to believe x files