“This serious-looking equation gave SETI a serious footing as a legitimate intellectual inquiry.
The problem, of course, is that none of the terms can be known, and most cannot even be
estimated. The only way to work the equation is to fill in with guesses. And guesses—just so
we’re clear—are merely expressions of prejudice. Nor can there be “informed guesses.” If you
need to state how many planets with life choose to communicate, there is simply no way to make
an informed guess. It’s simply prejudice.
As a result, the Drake equation can have any value from “billions and billions” to zero. An
expression that can mean anything means nothing. Speaking precisely, the Drake equation is
literally meaningless, and has nothing to do with science. I take the hard view that science
involves the creation of testable hypotheses. The Drake equation cannot be tested and therefore
SETI is not science. SETI is unquestionably a religion”
Michael Crichton
In the decade or so since Michael Crichton passed away we’ve been able to get an accurate value for one of the terms, nearly every star surveyed for gravitational wobble has been found to have planets.
That’s the value of the Drake equation, it provides a framework telling us what we don’t know, what we need to find out, and where each new data point fits in the whole scheme of things.