Aliens?

Imagine you are walking alone, at night, on a rural Nevada road. It is a clear night, and you pause to look up at the millions of visible stars. You see an especially bright light. A planet, maybe? A galaxy. As you peer at it, wishing you had a telescope, you realize the light is growing bigger. And it's heading straight towards Earth. Nervous, you keep walking. Glancing up again, you see the light is greenish, triangular-shaped, and emitting a high-pitched sound. Could it be a missile? Area 51 is nearby. Then you freeze, remembering the rumors about the military base. You look at the light again. It has landed in a nearby field, and strange, alien figures are pouring out of the ship. You have just witnessed the beginning of an invasion. An invasion that will lead to the end of the world.

http://www.ufocasebook.com/show/alien50.jpg

As much as scenarios like these are unlikely, they are very popular in science fiction books and movies.But could they really happen? Some of the questions will hopefully be uncovered on this page.

__Extra-terrestrial life (a.k.a. aliens)__ This counts as any life that did not originate on Earth. Though human-like creatures from outer space fall into this category, so does harmless bacteria-like organisms. Some scientists, such as __Stephan Hawking__, believe life has to exist in outer space. Because the universe is so huge, it would be highly unlikely that Earth is the only planet out of countless others that supports life. Two other hypotheses suggest that life emerged independently at many places throughout the universe, or that life spread between habitable planets. All life on Earth is made up of the same elements. Since Earth and other planets are made up of chemical elements formed from dead stars, other planets may have the same elements that Earth does. Therefore, it may also have the life; but certain temperatures, conditions, and chemicals are required.

__Communication__ As stated above, aliens don't have to be intelligent. But we are still trying to communicate with them:
 * over 100 years ago people suggested signaling to extra-terrestrial life on Mars or the moon by creating giant geometric shapes in in deserts or the tundra
 * inventor Charles Cros attempted to get funds for a giant mirror to signal to Martians
 * Nicholas Tesla thought his Tesla coil could communicate with beings from outer space
 * several people have devised languages: Lancelot Hogben created Astraglossa, a mathematical language, in the 1950s; Lincos, published by Hans Freudenthal, expands upon Astraglossa; Carl Sagan, in his novel //Contact,// explores how to create a message to communicate with aliens; Jack McDevitt, in his book //The Hercules Text,// describes a message based on powers of 2; in 1992 Carl Devito and Richard Oehrle based on physical scientific properties
 * Pictorial messages assume the receiver can see, and can understand basic math. This may not be all that effective, as symbols can be interpreted in different ways.
 * Famous pictorial message: in 1977, the Voyageur probes carried two golden records inscribed with diagrams of humans and the location of aour solar system, and recordings of pictures and sounds from earth
 * http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html has more information about the records
 * scientists have also found planets/ moons/ solar systems

__A theory on why aliens haven't found us yet (or maybe they have . . .)__ The Fermi Paradox points out that if aliens exist, why haven't ever visited us? You could argue that aliens have been on Earth, and we just haven't seen them, but Enrico Fermi offered a valid point. Unfortunately for Fermi, Rasmus Bjork, a Danish physicist, believes he has solved the paradox. Using a computer simulation of our galaxy, he devised a scenario in which aliens sent out probes to search for life. If the ships could travel as fast as 1/10th the speed of light, in 10 billion years they still would have only explored 4% of the galaxy. They could always detect television and radio waves, but even then, Mr. Bjork says, it would still take millions of years to find us.

__If we do contact some form of extra-terrestrial life, is it good for us humans?__ Most likely no. As Stephan Hawking said, "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans." Earth has valuable resources (water, metals, a wide variety of organisms) that aliens might want, assuming they manage to get to Earth. If aliens do ever set foot on planet Earth, they will probably wouldn't be very good at communicating with us. Just imagine if humans discovered a planet, full of precious metals and plants, inhabited by seemingly unintelligent creatures. Things wouldn't turn out to well for the planet. But even if they are friendly, they may unwittingly bring microbial organisms with them. These alien life forms probably couldn't be acquired by a human, but they could be toxic. This hypothetical event is called back-contamination, and it, not intelligent aliens, could be the cause of our demise.

__What about abductions and "take me to your leader" and little green men?__ That, I'm sorry to say, is from movies, books and myths. Here's how I see it: why would they abduct us when they have the technology to take over out planet (they would have to be highly advanced to travel great distances in space). Also, we are not the only creatures on Earth. There are way more bugs (or even trees!) then humans, so they might try to contact them. Finally, even if they could speak a human language (why English?), they might not be able to hear, or see, or feel or taste. They might even have senses that we don't have. And they could be 100 feet tall, or 1 inch tall, or look nothing like humans. So my advice is that you will probablly recognize an alien if you manage to see one. And that alien will do you no good, so stay away. But it is most likely more intelligent than you, so pretty soon you'll be witnessing total world domination, or destruction, or whatever else that extra-terrestrial life has in mind. []