Where are they?

Occam's razor (also written as Ockham's razor, Latin lex parsimoniae) is the law of parsimony, economy, or succinctness. It is a principle stating that among competing hypotheses, the one that makes the fewest assumptions should be selected.

In the Carl Sagan inspired movie Contact, it is stated that on the basis of Occam’s razor one must conclude that there is intelligent life elsewhere in the universe.

This is a fallacy. Among the competing hypotheses (life or no life), that of no life makes the fewest assumptions. In fact it is based upon the direct evidence, while the hypothesis of life is based on probabilities and all sorts of excuses as to why we can’t find extraterrestrial life.

A more appropriate evaluation of the situation may be contained in Fermi’s paradox. The Fermi paradox (or Fermi's paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity's lack of contact with, or evidence for, such civilizations.

In 1950, while working at Los Alamos National Laboratory, Fermi had a casual conversation while walking to lunch with colleagues Emil Konopinski, Edward Teller, and Herbert York. The men discussed a recent spate of UFO reports and an Alan Dunn cartoon facetiously blaming the disappearance of municipal trashcans on marauding aliens. They then had a more serious discussion regarding the chances of humans observing faster-than-light travel by some material object within the next ten years, which Teller put at one in a million, but Fermi put closer to one in ten. The conversation shifted to other subjects, until during lunch Fermi suddenly exclaimed, "Where are they?" (alternatively, "Where is everybody?"). One participant recollects that Fermi then made a series of rapid calculations using estimated figures. (Fermi was known for his ability to make good estimates from first principles and minimal data, see Fermi problem.) According to this account, he then concluded that Earth should have been visited long ago and many times over. [from Wikipedia]

Should have been? Sure, but just like the situation with Occam’s razor, there is no conclusive evidence of such visits. Arthur C. Clarke suggested that our very existence is evidence of such visits, but that's just a fantasy and a clever way to deny the existence of God.

So, if they must exist where are they?

Tomorrow: Intelligent design, fact or fantasy? (posted 12/17)