Where Are They? – Part 2

In the previous entry in this series of blog posts about the possibility of alien life in our galaxy, and especially about such life visiting us here, I speculated about the wide disparity between the knowledge we’ve obtained about the universe—which is substantial—and our ability to move around in that universe—which is miniscule.  We’ve only just gotten to the moon.  Is that the reason we’ve never been visited by aliens from other star systems—that the distances are just too immense and space travel is not as easy as our science fiction stories make it out to be?  Or is it that they are really nowhere to be found?

There’s certainly no shortage of stars in our galaxy around which planets could form that potentially could harbor life.  But before any civilization can visit us here, a lot of things have to happen.  It has taken us 2 billion years and several major extinctions for us to reach the sophisticated level we’re at right now.  We can see galaxies that are billions of light years away, but we’re a long way in time from journeying there.  We’re a long way from visiting even just the nearest star for crying out loud!  Any other intelligent civilization almost certainly has to go through that same process of learning about the cosmos before they can make the leap from simply knowing about the presence of other suns out there, to actually visiting them.  That’s a huuuuuge step.

So, I’m wondering, how many civilizations out there have actually made that step?  Or is there a limit to what a civilization can do?

There’s a hypothesis about alien civilizations that postulates a “Great Filter” that has prevented most if not all civilizations from reaching the ability to travel the galaxy and visit us here on Earth.  Somewhere, the Great Filter suggests, in the evolution of a civilization, the inhabitants of a planet reach a stage where their ability to continue is blocked.  That’s a legitimate argument, especially as there are at least two processes that could possibly prevent us on Earth from moving on to visit other planets and star systems—annihilation either by nuclear war or by global warming.  We haven’t done a particularly good job in reducing the risk from either one lately.  But it’s one thing to postulate that, on the one hand, these processes are a risk for us on Earth, and, on the other, transferring those possibilities to other planets.  In some respects, the Great Filter seems almost too anthropomorphic, that what happens on Earth must, of necessity, happen on other planets.

One thing we can be sure of, however: that an alien civilization must acquire knowledge about the universe and the galaxy in which we live in order to visit us here, and it must develop the means of transportation around it.  But where does that knowledge lie that would allow them to close that gap?  Does it exist?  Don’t look to science fiction for the answer.

It’s entirely conceivable that a breakthrough will occur in the (near?) (far?) future that will allow us to travel to distant star systems.  I’m not ruling that out.  And it’s also possible that knowledge is available to any and all civilizations which can reach the highly sophisticated stage where they have access to it.  It’s more a question of a civilization being able to make it to that stage.  How many civilizations have reached that stage?  None?  Or does that knowledge even exist?  At least that would answer the question: “Where are they?”

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