Fermi Paradox

Alien Head with "No Symbol" in red in front of it.

Could We Be Alone in the Cosmos?

It’s something people tell me all the time, and usually in hushed tones: “with a trillion planets out there, we really can’t be the only intelligent beings in the galaxy.” In other words, given the enormous amount of real estate in space, aliens are sure to exist. I don’t dispute this straightforward idea because, after all, it underpins the search for extraterrestrial intelligence (SETI). But…
Enrico Fermi

If extraterrestrials are out there, why haven't we found them?

"Where is everybody?" For those who want to understand why we haven’t found any space aliens, the Fermi Paradox is as popular as cheeseburgers. First proposed by physicist Enrico Fermi in 1950, this perennial head-scratcher rests on the idea that it would take only a few tens of millions of years for an advanced civilization to colonize the Milky Way — leaving their mark on every last star…
alien civilization

Fermi Paradox

Our Galaxy Should Be Teeming With Civilizations, But Where Are They? Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right? It's been a hundred years since Fermi, an icon of physics, was born (and nearly a half-century since he died). He's best remembered for building a working atomic reactor in a squash…

Zookeepers, Alien Visitors, or Simple Life

How Can We Explain Our Isolation? We seem to have the Galaxy to ourselves. At least, thats the obvious conclusion from the apparent lack of aliens in the neighborhood. But this conclusion might be a bit too obvious, and possibly wrong. In previous articles, weve considered why extraterrestrial intelligence even if common would have restrained itself from spreading to every half-decent star…

What's Blocking Galactic Civilizations?

Could galactic empires exist? In a previous article, we noted that there has been plenty of time for aliens keen on colonizing the Milky Way to pull it off. However, we see no signs of galactic federation ("Star Trek" aside). Why does the cosmos look so untouched and unconquered? What is keeping advanced extraterrestrials from claiming every star system in sight? This puzzle, known as the Fermi…