According to the British physicist Stephen Wolfram, intelligent life is inevitable. But there is a hitch. Although intelligent life is inevitable, we will never find it -at least not by looking out in the Milky Way. As evidence Wolfram points out In order to compress more and more information into our communication signals - be they mobile phone conversations or computer- we remove all redundancy or pattern. If anything in a signal repeats, then clearly it can be excised. But this process of removing any pattern from a signal make it look more and more random - in fact, pretty much like the random radio "noise" that rains down on Earth coming from stars and interstellar gas clouds.
ET artifacts coordinated by computers would look far more like a natural artifact. It is easy to distinguish a technological artifact such as a car from a natural object such as a tree. The tree is far more complicated. But, says Wolfram,"this is simply because our technological artifacts are primitive. As they become more complex - with computer processors enabling them to make a moment-by-moment decisions - they will begin to look just as complex as trees and people and stars." We have slim chance, he suggests, of distinguishing an ET artifact from a natural celestial object.
If Wolfram is right and ETs are out there but we will not be able to recognize them - either in their communications or their artifacts - then of course they could be here in the Solar System and we would not have noticed.
Wolfram thinks ETs will not want to travel to Earth - or anywhere else for that matter. In Wolfram's view, everything in the Universe is the product of a computer program. In fact, he imagines an abstract cyber-universe of all conceivable computer programs, all the way from the simplest up to the most complex. This "computational universe" contains everything from the Apple Macintosh operating system to a programme for creating a faster-than-light starship
Wolfram believes he has found nature's big secret - how it generates the complexity of the world, everything from a rhododendron to a tree to a barred spiral galaxy by applying simple rules over and over again as a simple computer programs. Wolfram came to this remarkable conclusion in the early 1980s when he discovered that the simplest kind of computer program - known as a cellular automaton - can generate infinite complexity if its output is repeatedly fed back in as its input. Wolfram has found evidence that the kind of computer program that produces endless complexity can be implemented "not just systems of biological molecules but in all sorts of physical systems - chaotic gas clouds, systems of subatomic particles and so on. He concludes that all over the Universe life - though definitely not life as we know it - will spring up spontaneously. It is a fundamental feature of matter."
The existence of this computational universe is the crucial thing. But the reality is it would be it easier and more efficient for an ET civilization to stay at home and use a computer to search the computational universe for useful programs rather than try to get the same information by hunting for ETs to talk to among the 200 billion or so stars in the Milky Way. "It's a simple numbers game," says Wolfram.
Everything is generated by computer program,"and that includes you and me," says Wolfram. "Someone halfway across the Galaxy could have found the computer program for you and conversing with you at this very moment."
Casey Kazan via ] M. Chown,The Universe Next Door and A New Kind of Science by Stephen Wolfram http://.wolframscience.com/nksonline/toc.html