SocraticGadfly: More on why the Drake equation is problematic

July 20, 2011

More on why the Drake equation is problematic

Detailed readers of this blog know, or show, that I consider SETI, the Search for Extra-Terrestrial Intelligence, to have thin scientific foundations at best and to be quasi-religious at worst, just as the cartoon above from XKCD shows.

Well, a recent post at Skepticblog has only reinforced this. And, yes, it's by ... cornucopian futurist Michael Shermer.

Here's Wiki on the Drake equation and its background:
Considerable disagreement on the values of most of these parameters exists, but the values used by Drake and his colleagues in 1961 were:

R* = 10/year (10 stars formed per year, on the average over the life of the galaxy)
fp = 0.5 (half of all stars formed will have planets)
ne = 2 (stars with planets will have 2 planets capable of developing life)
fl = 1 (100% of these planets will develop life)
fi = 0.01 (1% of which will be intelligent life)
fc = 0.01 (1% of which will be able to communicate)
L = 10,000 years (which will last 10,000 years.
The first two parameters' estimates aren't controversial to me. From what we've seen of early exoplanetary findings, the third could be moderately too high.

From there, we really have shinola hitting the fan, IMO.

Fl at 100 percent? No way, Jose. Let's put it at 10 percent instead. Fi at 1 percent? No way again. Even if "intelligent" is defined loosely, let's take that down to 0.1 percent.

And, there again, we have problems with the "sieve," which modern evolutionary biology teaches us.

What's "intelligent" mean? Crows, ravens and other corvids are arguably intelligent, we now know. What's "communicate"? An animal like a vervet monkey not only has different calls/alerts for different predators, members of a tribe can fake the calls to steal food.

And "L"? Given exactly how we define "civilization," our own 10,000 years may be just about up, if we start with the development of agriculture. If we start with, say, the steam engine, we have plenty of life left. This is just Drake spitting in the wind on this number.

Another commenter there calls the set of equations a sieve. Well, that may or may not be true, but, shouldn't one show more rigor with defining a sieve? The numbers up to "L" could be more legitimately argued, but that one? Since it's so problematic, why didn't Drake leave its value blank.

(That said, Shermer is much more pessimistic on "L" than Drake, once setting it at just 420 years.)

Per Wiki, Michael Crichton notes:
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. [...] 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...
A basically undefinable sieve isn't much of one.

Beyond that, here's the bottom line on SETI, and the interpretation of the Drake equations that began with Frank Drake and extend to it:

If the unspoken presupposition of L is "communication with aliens," Davies covers all the *problems* with that one, too.

How do we know that aliens communicate the same way we do? Take the gold "CD" sent with Voyager. If aliens don't "hear" at all ... the music and other sounds on it mean not a damned thing to them.

In other words, I think SETI is still too anthropocentric and so does Paul Davies, as he discusses in detail in "The Eerie Silence."

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