It's too late to worry that the aliens will find us
newscientist.com
newscientist.com
And Earth has been broadcasting "I'm alive!" for at least 2.4 billion years, since the Great Oxygenation Event: http://en.wikipedia.org/wiki/Great_Oxygenation_Event Ever since then, any intelligence within the area of probably several hundred light years or more has had the ability to take a simple spectrograph of our planet, observe free O2 in the atmosphere, decide that's too likely to be the result of life for comfort, and obliterate the planet.
Nobody has. (Unless you believe the official Current Earth Destruction Status: http://qntm.org/board However, it appears to simply be instrument failure. Somebody really ought to fix that.)
Even on the galactic timescale, 2.4 billion years is not chump change.
Either the game theoretic optimum is not to smash your neighbors immediately (for instance, widespread orbital colonization is indeed practical and is what happens, which as people have observed changes the balance away from "smash"), or we are effectively alone. Either way I think we can discard the relatavistic-projectile-death scenario, except as a major, unplannable fluke.
But you're right: the fact that our suspiciously life-supporting planet has been sitting here for billions of years unmolested does appear to indicate that there aren't any planet-destroying game theorists in our neighbourhood.
Alternative scenario: instead of a relativistic projectile, they sent a starship, which will leave us alone unless we develop enough technology to be a threat to its home planet. If we think that's a likely scenario we should all be sitting around worrying about how to not piss off the starship.
On the other hand, since knowing about the starship is a threat to the starship, we should try to avoid even thinking about whether there might be a starship.
(Far, far more likely in my mind would be the uplift scenario, that helping these civilizations would be seen as a moral duty once that was actually a real possibility. And it also sort of requires Star-Trek-like limits on technology as well; the Federation lacks the capability to rewrite a primitive civilization from the gene level up, but that seems an unrealistic limitation in real life. And that's not even what I consider the "most likely" scenario; I'm just saying that anyone who tried to instantiate the Prime Directive would probably break down into this moral duty idea pretty quickly. Why sit and wait for them to develop when you can just make it happen? Artificiality of development is a small concern next to potentially billions of unnecessary deaths. Whoever is out there, watching us war and burn and die and doing nothing, is not being an upstanding moral citizen.)
Really? Do you go out of your way to stop fish and insects from killing each other?
edit: I admit this was a badly phrased example. Fish and insects rarely kill each other.
It could be that to aliens, our planet's shared culture is still too close to tribal warfare for them to be comfortable raising us to their level. It wouldn't be quite the same as the Prime Directive as a motive, but it would have the same effect in a lot of situations.
Am I limited to either putting my child immediately in the driver's seat of my car or tossing him out into the wild and letting him fend for himself? My point not being that we are metaphorically children; I don't like metaphors like that, we are what we are and we have no idea whether we are or are not like children. My point is that we are not limited to such constrained choices.
It actually comes from my observations of politics on earth. Countries with closely shared cultures and correspondingly close levels of advancement in certain areas tend to be more trustworthy with the technology they create than countries that were previously poor and balkanized. Most of our intrusion in Africa and the Middle East, even when it's intended to help, tends to just get more people killed. This is not to say that everyone there is a savage, but their culture just isn't at a point where it prepares the citizens or the leaders to handle elements of our culture properly.
I don't see how a parent and child relationship is applicable here either. It doesn't tend to happen that way in international politics, so I see no reason to believe it would be more like that on a galactic scale.
Yeah, good point. If nothing else you reset the clock to zero, and that buys you an awful lot of time even under the worst case scenario.
"instead of a relativistic projectile, they sent a starship,"
A starship is a relativistic projectile that bothers to slow down. If you're going to smash a planet that acts up, you might as well just cut to the chase. All even-remotely-physically-plausible forms of interstellar travel are also intrinsically planet-busters, including the various exotic FTL drives that hover on the edge of plausibility.
Sure, but they might not be complete dicks. They might not want to kill us unless we're a threat to them.
The more I think of it the more unlikely the kill-everyone-immediately strategy seems. Suppose you're Robinson Crusoe. You've been all alone on an island for five years. One day you're out hunting and you see another human. Do you pull out your gun and shoot him in the head before he can do the same to you? Or do you take the calculated risk that he isn't a homicidal quick-draw champion?
It's worked so far. No possibly-homicidal-quick-draw-champion aliens encountered today! Good job, Team!
OR
Or perhaps this is a grim answer to Fermi's Paradox: the galaxy is quiet because someone preemptively wiped out the competition a long time ago.
Except us?
Nuked the planet? Find out where they came from. Tried to contact, and eventually left, after some vague friendly gesture? Might not try to kill you.
Awww :'(
I do not want to insult Quetyzcoatl by comparing likelihood of his existence to that of space aliens. Evidence of winged serpent gods is lacking, but since the Drake Equation means that anything which makes for a good sci-fi novel is good enough to write a grant proposal for, I suppose I should cover my bases.
How? If radio waves travel at the speed of light and the first radio transmitters were in operation in the late 1800's, this would mean that the transmissions would be no further than 150 light years or so.
There are stars in this range, sure, but I'm interested in how antennas outside of this range might be able to pick up the signal.