Saturday, June 16, 2007

The Drake equation and the Doomsday Argument

The Drake equation:
The equation is usually written: N = R* • fp • ne • fl • fi • fc • L
Where, N = The number of civilizations in The Milky Way Galaxy whose electromagnetic emissions are detectable, RIGHT NOW.
R* =The rate of formation of stars suitable for the development of intelligent life (per year).
fp = The fraction of those stars with planetary systems.
ne = The number of planets, per solar system, with an environment suitable for life.
fl = The fraction of suitable planets on which life actually appears.
fi = The fraction of life bearing planets on which intelligent life emerges.
fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = The length of time (on average) that such civilizations release detectable signals into space (in years).

Plausible values from observation/ current astronomical theory/ taking solar system as representative:

5 per year x .5 x 2 x .5 x .5 x .5 x 10000 years = 6250 ETIs broadcasting at this very moment
(N= .625 L, so if L = 10000 years)

If this is right, we should expect to detect ET signals any time now, and SETI is about to make a discovery that will change our view of ourselves forever. But....

Rare Earth hypothesis: fl and fi are extremely small, so no ETIs exist (N<1).

Doomsday hypothesis: intelligent civilizations quickly destroy themselves, so L is not much more than 80 years - so no ETIs exist (currently - past ones quickly died), AND we will destroy ourselves soon.

I believe the Doomsday hypothesis is correct.

Have a nice day.

2 comments:

Dan said...

We can always count on KA to brighten our day...wasn't it in Contact that the first signals the other planetary residents received were television broadcasts of a Hitler speech?

Keith said...

Yes, but a bit of dramatic license, as radio and some TV signals were beamed out earlier, and so high power signals date from the 1920s. Nonetheless, Hitler will be among our earliest emissaries to the stars.