Susan Schneider is a philosophy professor at UConn-Storrs. She's publishing a very interesting paper on the likelihood that any alien life with whom/which we come in contact will be artificial rather than biological, or post-biological. Her reasoning is sound in my opinion:
First, in order to communicate over vast distances a civilization must first invent and master radio waves. That civilization is only maybe 50 years from computational machines(computers) and only 50 or so years after that, the beginnings of hybridizing those computers with biological intelligence. We are already experimenting with neural implants to manage disease processes and enhance human intelligence, imagine where we'll be in another 50 years or 500 years.
Now, carbon-based creatures are abysmally ill-suited for deep space travel while silicon-based "creatures" would be perfectly suited for it. Additionally, human brain neurons are 7 orders of magnitude slower at processing than silicon-based networks. The human brain partially compensates with massive parallel processing but human performance requirements such as attention and concentration are definitionally serial in nature.
Lastly, carbon-based life-forms require huge amounts of water to survive, severely limiting travelling distance. Silicon-based life-forms require only energy which can be nuclear, solar, kinetic, etc., not limiting travel duration at all.
These three likely aspects of alien beings suggest that any civilizations that might reveal themselves to us will necessarily have been around for thousands or millions of years longer than us and therefor will be advanced and vastly superior in intelligence on a level we probably can't even comprehend.
And I for one, welcome our benevolent, silicon-based overlords as they shepherd humanity toward a better tomorrow......or eat us, whichever.
Here's a link to an article about it: http://motherboard.vice.com/…/the-dominant-life-form-in-the…