Well said, Jeryst. I've often thought that if we had a time machine and could take a man from the ancient world and bring him forward 3000 years to our time, he wouldn't be able to comprehend what he was seeing. He simply wouldn't have the capacity or background to understand. Imagine - airplanes, computers, telecommunications, robotics, refrigeration, gas grilles, even the light bulb. He would find many of the things that we take for granted as conveniences of modern life to be sorcery, smoke and mirrors. Even someone from colonial America would be amazed. Would it be any different for us?
That doesn't address the question about whether life exists elsewhere - just one of the challenges we're up against in knowing what to look for. Science is mute at this point about the existence of extraterrestrial life. All we have is a statistical likelihood, based on the information gathered about how life may have formed on this planet and extrapolating it statistically to the innumerable stars in our galaxy and in the universe. Given the sheer numbers of stars, it's statistically likely that life formed on other planets in the universe. But until someone can present hard evidence that life exists on other worlds (see
http://en.wikipedia.org/wiki/Definition_of_life ), it's all conjecture and suppostion. It doesn't mean life exists on other worlds, but it doesn't mean it doesn't. Science simply cannot say yet. "Beliefs" about life on other worlds doesn't enter into the equation where science is concerned.
Speaking of which...P.G. mentioned something about "what scientists would have us believe." While his example was purely tongue-in-cheek (I hope), the underlying concept - that science "wants us" to believe something - bears further scrutiny.
Pure science and it's practioners will not have anyone "believe" anything. Science deals with observation, hypothesis, validated by testable, repeatable empirical results to arrive at a theory. That theory is subject to review and revision when the facts fail to agree with the hypothesized result. It presents facts and says "Here's the best explanation I can come up with why this happens this way." If someone can come up with a better explanation that better fits the facts, pure science demands that this new explanation be adopted as truth. Science offers no moral judgement on the facts - it merely presents them. Here's some more about the scientific method:
http://en.wikipedia.org/wiki/Scientific_methodMany good people of faith believe that, because science offers alternative explanations about the origin of the universe and the origins of life on Earth from the creation stories taught in many religious traditions, that science and, by extension, scientists as a group, deny the existence of God (or gods, in a nod to our Hindu and other pan-theist friends). In fact, science has nothing to say about the existence of any deities because, as of yet, the existence of God is not a testable hypothesis by empirical means. In fact, many scientists believe in the existence of God, taking it as an article of faith that He exists. Others choose to extrapolate the lack of empirical evidence as evidence that God doesn't exist. For now, the existence of God remains a philosophical debate. Science has no answer one way or the other.