Scientists are apparently convinced that the universe is so vast that the it’s near-certain there is other intelligent life out there. I’ll take them at their word.
That said, though, the observable universe is a very tiny fraction of that. Then you reduce that further when you consider the portions of the observable universe that we can really interact with, especially by radio, and the odds of us making contact in this manner are sadly tiny. So it’s not surprising that we haven’t found anything concrete through our couple of little projects, I guess.
Hey, we’re beaming Hendrix into space. If they’re not cool enough to appreciate it, the hell with them. They can’t be that advanced.
Unfortunately that’s not the only thing being sent out into space. Wasn’t one of Hitler’s speeches one of the first?.. and if any of our news porgrams make their way out there, they all know what a violent civilization we are…
If only we could filter what we send out, we may have better luck!
I don’t know any scientists who say that. The problem with making any predictions about the frequency of life is that we only have one data point. Until we find life somewhere else that arose independently, we really don’t know.
This is a bit reason why programs like SETI are important, even if they return negative results. Because in this case, a negative result is a result. And the question to be answered is one of the most important we can ever ask: are we alone?
I don’t know any either. I do know what’s said every time we discuss things like “is there life anywhere else in the universe?” From that, I gather that some scientists think it’s a lead-pipe cinch, and I’m sure that’s not uncontested, but it makes enough sense for me in the abstract. In these threads, I think it’s an okay working assumption.
Who knows? The thing is, directed energy is much, much more efficient than broadband when sending point-to-point communications. And satellite relays means we don’t need high power transmissions. In the 50’s, HAM operators were operating 1000 watt transmitters to talk around the world. Today we do it with cellphones that use a tiny fraction of that power. TV transmitters may be moving to cable.
Maybe the communications of the future involves very low power, extensive Wi-Fi grids that blanket most of the planet.
Or maybe there’s a whole 'nuther communications medium that we just haven’t stumbled onto yet, and would be undetectible by us today if others were using it.
It wouldn’t surprise me at all to discover that the EM signature of a civilization grows like crazy during the early industrial ages, and then suddenly drops precipitously as it becomes archaic and inefficient compared to new technologies.
SETI tells us that nobody within 5 light years (see map) is broadcasting TV or radio, nobody within 50 light years (map) is using military radar, and nobody in this galaxy has been sweeping the skies occasionally with a powerful gigawatt beam, like we did once twenty years ago (ie.Arecibo), just to see if anyone sent anything back. So, at 20 light years I believe they could detect military radar (but not TV or radio) having “structure”, and could certainly detect the deliberate high powered emissions. TV and radio fades to become indistinguishable from noise within a few light years.
Now, this does not necessarily mean that there is nobody there, but the alternatives are all unlikely for one reason or another:[ul][li]There might be a ruthlessly enforced galactic silence policy, and nobody uses electromagnetic signals any more. However, each such civilisation could still not prevent the leaks from their technological infancy, and it is difficult to believe that nobody, not even a malfunctioning piece of equipment or a mischievous joker, ever lets slip an electromagnetic signal detectable by the incredibly sensitive receptors on Earth.[]The aliens might have encased this planet in a “shield” impermeable to transmissions. Unfortunately, this would require such enormous resources and manipulation of spacetime that we might as well suppose that they are keeping us in the Matrix.[]To disagree slightly with QED, perfect compression is indistinguishable from noise (ie. a signal which has been coded for optimum efficiency simply sounds like a detuned radio). This is a genuine possibility. However, again, there must surely be some leaks from way back when the coding was imperfect, and it would seem imprudent to code eg. emergency beacons so that they couldn’t be identified.[/ul][/li]
Put simply, if everyone is trying to be noticed as half-heartedly as us, we’ll never find them, and so it is still entirely possible they are out there in this galaxy. However, there are two definite facts:[ul][]The technology required to emit a galaxy-wide audible signal is only as advanced as that required to make a nuclear weapon. [] We appear to be the only ones ever to have done so.[/ul] One wonders whether the two facts are related.
Didn’t Fredrick Pohl’s Gateway series mention something like that? That every race that got advanced enough to start broadcasting a lot got smushed by belligent silicon based aliens?
I don’t think this helps us much in our search. Developments in the last 20 years on earth have made our signals appear much more random. Unless you know the exact symbols used for modulation the signals look pretty much like noise and this will be getting worse not better as time goes on. I don’t think there is much reason to believe that aliens won’t be using these wider bandwidth communication techniques.
Perhaps all existing ET civilizations with interstellar-travel technology in this region of the galaxy have some sort of Prime Directive against interference with primitive races like ours, and their version prohibits them from even tipping us off that they exist. (But it does allow for the occasional clandestine anal probe! )
Either that or they’ll come looking for us demanding to know if the castaways ever got off the island, and threatening to blow up the earth if they don’t see that episode.
I would think given the extreme size of the universe that intelligent life occuring at least one other time is certain. But for our purposes, isn’t finding another occurence of life here in the Milky Way the only thing that matters?
Remember, also, that if we were to visit another planet, even one with life on it, that planet has a very long past and (presumably) future, and all we see is the one momentary single-frame or snapshot in the evolution of its biosphere. And there’s no reason why evolution on one planet would be on the same timetable as on any other planet. If ET’s had visited Earth at any time in the past two billion years there has been life here, but before the emergence of the genus Homo a mere 2.5 million YA (a mere eyeblink by comparison), they would have reported, “No intelligent or proto-intelligent life found.” And said ETs, by now, might have either gone extinct or evolved into something beyond our comprehension – either way, no longer reachable by SETI.
