What would "Star Trek" be without Mr. Spock? Or "Enterprise" be without Dr. Phlox? Or hell, "Babylon 5" without Bruce Boxleitner (Ok, I know, that actor isn't an alien ... but how do we know?)

Joss Whedon is going to test that theory this fall when "Firefly" debuts on Fox.

"I believe we are the only sentient beings in the universe," said Whedon, best known for creating "Buffy the Vampire Slayer."

"And I believe 500 years from now, we will still be the only sentient beings around."

Whedon told Sci-Fi Wire that the formula used for science fiction series has become tired and old, and that the fact that having only humans in space and no one else has never been explored.

"I wanted to stay away from the easy science-fiction fixes -- the android, the clone, the alien -- all the stuff that, for all I know, may be lurking arund the corner, but I'm not expecting to see anytime soon," he said. "(Aliens are) a great metaphor to play with, but it's not really what I'm interested in. I'm really interested in 'You are there.' In 'You are part of this.' And I think aliens, no matter what, take you out of that. I also need to spend some time away from latex."

"Firefly" premieres this fall on Fox.