Tuesday, November 11, 2014

Collect call from E.T. Do you accept the charges?

[EarthSky] How many times have you watched Close Encounters of the Third Kind, or Independence Day and wondered if what happened in those films could ever really occur?
Well, that day may be getting closer as things start to get interesting in the search for extraterrestrial life.
A recent discovery proves that as much as 50 percent of the water on our planet predates the sun. Not only does this indicate water is more prevalent than we thought, it also means that many more worlds throughout our galaxy probably have habitats conducive to life. In our own solar system, even worlds like Jupiter’s moon Europa, and Saturn’s moons Enceladus and Titan, may host some form of life. This means the so called habitable zones – the specific orbits around stars, for example, at Earth’s distance from our sun – are no longer the only places where life can get started. These small moons don’t get all their energy from the sun. They also get energy from the gravitational push and pull of their host planets. Conceivably, there could be as many as a billion worlds in our galaxy with living things on them.
When speaking of technically advanced civilizations though, those numbers change dramatically. To evolve beyond one-celled organisms takes an extraordinary set of circumstances and an equal dose of luck. The number of starts and stops for life on a distant world probably outnumber all the grains of sand on a large California beach. If however, just a tiny fraction of those worlds with life develop into societies able to communicate, there could be at least 2,000 in our galaxy alone.
So, why in the 54 years since SETI began searching for extraterrestrial radio signals, haven’t we heard a thing?
First, the majority of stars in our galaxy are much older than ours and very far away. A signal from a distant civilization might arrive tomorrow or 100 years from now. When you compare the 4.5 billion years our planet has been around to the almost 15 billion years the universe has been in existence, our 54 years of searching for intelligent civilizations beyond Earth doesn’t amount to much. In fact, it equals about a hundredth of a second on a 24-hour clock.
Also, advanced extraterrestrial societies have probably evolved far beyond radio communications by now. Recognizing signals from them might be comparable to a primitive tribe deep in the jungle listening for evidence of a larger world unable to pick up vast amounts of information from the Internet flying all around them. Even a radio signal from a civilization only slightly more advanced than us would be difficult to pick up. You’d have to be at the right frequency at the right time and be very lucky. Read More