SETI

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Search for Aliens - install the SETI@Home client and turn your computer into a SETI observatory. This will not interfere with your work - the client only activates when your computer has been idle for a while, it is a really neat screen saver, plus you may be the first person on Earth to hear ET...

How many civilizations are there in our galaxy? Try plugging your own estimates into the Drake Equation.

Searching for aliens on SETI@Home is productive and fun. Join a SETI@Home team and compete for the coveted #1 alien searching team. Besides, the SETI@Home screen saver is pretty nifty too.

The Drake Equation was first articulated by Professor Frank Drake back in 1961. It's goal is to estimate the number of intelligent civilizations that currently exist in our galaxy. So here goes with the actual equation, brace yourselves:

N = N* Fp Ne Fl Fi Fc fL

OK, OK, but what does it actually mean? Well here are the definitions for each coefficient:

N is the number of communicating civilizations that currently exist in our Galaxy.

N* is the number of stars in our galaxy. Astronomers say that this is about 200 billion.

Fp is the fraction of stars in our galaxy that actually have planets. On the SETI website, an estimate of 20% to 50% is given, but at the end of the day, I personally think that the fraction will be higher.

Ne is the number of planets per star capable of sustaining life. Again, SETI says estimates range from 1 to 5. Personally, I think it's probably closer to the higher end, if one also takes into accounts moons (e.g. Jupiter's Europa & Saturn's Enceladus were both shown to have liquid water).

Fi is the percent of potentially life supporting planets on which life evolves. Beats me... given that we have a data set of one (Earth, if you're wondering) any guess seems good.

Fc is the percent of planets harboring life, on which the life forms have the means and desire to communicate. What, we're not good enough for them?! SETI estimates this at 10% to 20% - personally, I think that this is seriously optimistic, but again, like my statistics professor used to tell his son: "Damn it Tanner, don't make an inference based on a single observation!"

fL is the percent of a life bearing planet's life during which a communicating civilization survives. Last year I heard Frank Drake speak about his famous equation. He clarified that Fl is also meant to capture civilizations that are still out there, but whose communications signature becomes undetectable for some reason.

So, what do we get? a lot of guesstimates. Using my own estimates, I get 180 civilizations out there in our galaxy right now. Not a very high number considering the distances involved. More qualified people have come up with numbers ranging from 0 to 10,000, so I don't see a reason to prefer their estimates to my own.

Try plugging your own estimates into the equation and see what you get.

Back in the 1960's, the distinguished physicist Enrico Fermi asked a simple, yet profound question regarding galactic civilizations: "where are they?" (the obvious answer "they're all at the mall", did not occur to him at the time). This became known as Fermi's Paradox.

The question is more sophisticated than it may seem at first glance. Consider the following three factors:

(1) the age of our Milky Way Galaxy is estimated at 13.6 BILLION years;

(2) it contains in excess of 200 billion stars;

(3) in the past 10,000 to 15,000 years man has moved from being a cave dweller to being a space traveller and a blogger (YES - the blogger is the pinnacle of civilization!).

From these factors one can infer that if there are civilizations out there, some must be older than us (given the age of the galaxy and the vast number of stars). If they are older by just a few million years, which is likely, they should be so technologically advanced that they should have colonized the entire galaxy by now (what, can't an alien take a bathroom break around here anymore?!).

Fermi's Paradox therefore, basically says this: "If they were out there, they should already be here. Since they are not here, they do not exist".

My surfer friend would say to this: "Harsh, dude." Shyeah...

Over the years many have tried to offer solutions to Fermi's paradox, including:

1. They are really not there...

2. They are out there, but they do not want to be seen.

3. They are out there, but they are not interested in space travel, communications or colonization.

4. They are already here... (oooo....spooky)

5. They are communicating, but we don't know how to listen.

6. They are obeying the prime directive, i.e. not talking to primitive civilizations (yeah, I'm a star trek fan. Wanna fight?!)

Personally, I believe in the scientific method. The sheer numbers of stars out there, and recent scientific discoveries (huge numbers of exoplanets; water on Encledus, Europa etc.), lead me to believe that it would be sheer pride to think that we are the only intelligent species in the entire galaxy. BUT until we find scientifically verifiable proof, Fermi's Paradox stands. In fact, with every passing year without a SETI discovery, the questions it poses become larger.

Well, humanity (or small portions thereof) have made a number of attempts to contact ET:

1. Radio and Television Broadcasts - the first radio broadcasts on Earth were made about 100 years ago. These original communications continue propagate outwards into space at the speed of light. This means that extra terrestrial beings located in a sphere with a radius of about 100 light years, centered on the Earth, who posess the necessary technology and who have the inclination to look for us, could find us by detecting our radio emissions.

2. Physical Messages - with the idea that these spacecraft destined for the stars may one day be located by alien beings, NASA scientists placed certain messages in the Pioneer 10 and 11 spacecraft, as well as into the Voyager 1 and 2 spacecraft. All 4 vehicles have now left the Solar System and are slowly (comparatively speaking) making their way in interstellar space. Should an alien ever find these craft, he would see images of earth, directions for locating our home planet and in the Voyagers' case, a golden disk containing sounds and pictures from the blue planet. Don't hold your breath though... the chance that a few tiny spacecraft would be detected by ET in the vast expanses of space are infinitesimal.

3. Intentional Radio Broadcasts - in 1974, the Arecibo radio telescope broadcast a short radio message towards M13, a globular cluster containing hundreds of thousands of suns, located 23,000 light years from Earth. Of course, any return message will take 46,000 years to get here, and the choice of a globular cluster as a target for the broadcast is considered by many to be a poor one, since scientists suspect that star density, composition and age would make globular clusters in hospitable to life. Who knows?

Humans have made a few other attempts to proactively contact ET, but there are no ongoing, sustained efforts to send messages to the stars. If we are not calling ET, could it be that they are as lazy as we are?

There are a number of places in the Solar System places where life could conceivably exist today, or could have existed in the past. At best, real evidence for such possible life is contravesial, but the search for life in the Solar System is far from over.

Here are some of the locations where our next door neighbors might lurk:

Mars - possible life signs include: fossilized bacteria in Mars meteors; traces of methane in the Martian atmosphere; possible positive result on chemical experiment conducted on Viking; existance of water on Mars in the distant past.

Europa - there is no evidence for life on Europa, however the moon is believed to have vast oceans underneath a thick layer of ice. On Earth, water = life. Of course, that does not mean that the same equation holds for the Jovian system.

Titan - there is no evidence for life on Titan, however, Saturn's moon is believed to be a host to a full blown methane cycle, in much the same way that Earth supports a water cycle. Further, organic compounds have been identified in the moon's thick atmosphere.

Enceladus - recently discovered to have liquid water, some of which is released into space by massive geysers.

Portions of Los Angeles - granted, it's not intelligent life, but we'll take what we can get.