# At Last, How Many Alien Civilizations are There?

astrobio.net

During the space age, 1961 was a special year: the Russian cosmonaut Yuri Gagarin became the first man to orbit Earth, while the American astronomer Frank Drake developed the now famous Drake Equation. This equation estimates the number of detectable extraterrestrial civilizations in our Milky Way galaxy, supposing our present electromagnetic detection methods. The Drake equation states:

N =  Ns x fp x ne x fl x fi x fc x fL

N = number of alien civilizations in the Milky Way
Ns  = estimated number of stars in the Milky Way;
fp = fraction or percentage of these stars with planets on its orbits;
ne = average number of these planets with potential to host life as we know it;
fl = percentage of these planets that actually develop life;
fi = percentage of these planets that actually develop intelligence on human level;
fc = percentage of these civilizations that actually develop electromagnetic radiation emitting technologies;
fL  = percentage of these civilizations that keep emitting electromagnetic signals to space. This factor is extremely dependent on the lifetime a civilization remains electromagnetic communicative.

# Aliens.

I asked a friend once, the alien conspiracy has been going on for centuries so there must be other intelligent lifeforms in the universe, right? To which he answered: I don’t know, intelligence is rare in this planet, how much more the universe.

But I wanna be objective so I’ll just ask the “The Drake Equation” for an answer. The equation was devised by Frank Drake and the Order of the Dolphin. It’s the bones of the SETI research.

They said you can get the “putative galactic census” using this equation. Say, I like that word, putative.

Drake Equation:

N = R x p x e x l x i x c x L

where:

• N = The number of intelligent civilizations,
• R = The average rate of star formation,
• p = The fraction of developed stars which possess planets,
• e = The number of potentially life-supporting planets for a given star,
• l = The fraction of these planets that develop life,
• i = The fraction of these planets where the life develops intelligence,
• c = The fraction of these planets where the intelligent life develops technology,
• L = The time during which the intelligent, technological life send signals into space,

Result:

R = 7, p = 0.5, e = 2, l = 0.33, i = 0.01 (1%), c = 0.01 (1%), and L = 10,000,

Giving N = 2.3.

Meaning:

The result is pretty low, only, 2.3. If the equation is true “then there may be just 2 civilisations in the Milky Way galaxy, Humanity, and one other”.

So yes, there might be intelligent lifeforms but they are very very far from us. In fact, if ever we meet one Dr. Drake said that they’d prolly be an immortal race.

According to Dr. Drake, Earth became only detectable starting 1950’s when we started using powerful television and radar transmitters that leak signals to space. But, the big transmitters are being phase out in favor of cables and satellites for economical reasons.

Hence, time will come when we no longer are leaking signals to space, we may still exist but we’d be undetectable.

So don’t expect War of the Worlds anytime soon.

Dennis Overbye, New York Times

www.suite101.com/content/the-drake-equation-a88713

# In Astronomoy Class

• Quiz Question: What's the purpose of the Drake Equation?
• Kevin: To find where Josh is.