Originally Posted by
Atrea
I don't think this question is very well thought out.
In order to really appreciate how astronomically unlikely it is that we will ever be in contact with another species, I refer to the "Cosmic Calendar"; in short, if 12:00 on January 1 was the Big Bang, and 12:00 on January 1 of the following year was "right now", then all of the events that took place in the Universe since its formation fall in between.
Our best estimate is that the Universe is 13.772 billion years old. Earth is 4.543 billion years old, which would place its formation somewhere on September 6th of the Cosmic Calendar. Our species, "homo sapiens" didn't appear on Earth until 11:52PM on December 31st of the Cosmic Calendar. The first human cities didn't appear until 11:59:46 - 14 seconds to midnight. In fact, Columbus didn't arrive in the Americas until 1 second to midnight.
Now, in the interest of simplicity, let's use that point (because otherwise we're dealing with fractions) as a reference point for when we started watching the skies. Of the 31,557,600 seconds in a year, we've only been looking for one of them.
How long will we be looking? Who can say how long the human race will live? Some cynics might not give us very long. But even optimists have to face reality: there will come a day when we are no more.
For argument's sake, let's say we live for another 1.58 million years -- hopelessly optimistic, I know, but there's a method to my madness: 1.58 million years corresponds to 1 hour on the Cosmic Calendar. So we live for another 3600 seconds. 0.0114% of the Universe's lifetime. A blink of an eye.
Now, this is all well and good, and you might be asking "What does this have to do with finding another species?"
Let's first make a few optimistic assumptions.
First, let's assume that life in our Universe is both abundant (likely) and intelligent (plausible, although probably not common). Let's also assume that it is something that would fit our definition life (probably, but not in all cases), and we could communicate with them (not likely at all.)
Consider first the size of the Universe. Then consider the extremely short window we're in it. Then consider the likelihood that another species will be in an equally short window. And finally, consider the chances that our "slice" of time intersects with their slice of time.
Are there other species out there, right now? Almost certainly. Intelligent ones, too. However, the likelihood that they will be at the point in their civilization where they will be able to communicate with us, while at the same time intersecting with our civilization's existence is very small. And then when you consider the huge size of the Universe - or even our galaxy - you see that the chances of all of these variables ending up in our favour are fairly low. Impossible? No. But chances are, most civilizations rise and fall without having ever met another.
I don't think ours will be any different.