Where are they? Why I hope the search for extraterrestrial life finds nothing.

I have a sci-fi inspired theory that as a civilization advances, it modifies itself such that it's mental processing speed and speed of communication become faster. At a certain point, species at other speeds have less to offer and communicating would be impractical as emitting a signal at our speed would involve what would seem like eons of effort to them. Due to the speed discrepancies, they'd mainly prefer talking to themselves.<p>One way or another, the "sends radio waves into space hoping for contact" phase is probably very short. The possibilities for what phases come next are not all bad, but whatever the "usual" is, it probably doesn't involve sending radio waves out anymore. It's possible the next step is to evolve into something that wouldn't like talking to us very much. Maybe that's not bad.

Charles Pellegrino/George Zebrowski covers this in _The Killing Star_ (1995). They reason as follows:<p><pre><code> 1. Any species will place its own survival before that of a different species. 2. Any species that has made it to the top on its planet of origin will be intelligent, alert, aggressive, and ruthless when necessary. 3. They will assume that the first two rules apply to us. </code></pre> So any starfaring species might well destroy another starfaring species -- immediately. In _The Killing Star_ the aliens do so at the first opportunity with high-powered relativistic bombardment. The power that they use dwarfs that generated by asteroid impacts and past mass extictions. They blanket the entire hemisphere of planets with relativistic projectiles! The earth is taken out entirely in just two shots.<p><a href="http://sites.inka.de/mips/reviews/TheKillingStar.html" rel="nofollow">http://sites.inka.de/mips/reviews/TheKillingStar.html</a>

I think I just found a possible alternative explanation, which given the odds might actually be very probable: there is one situation in which aliens might not want to show themselves to us. That is, if we are an experiment that their interference would mess up. Perhaps they are just studying some sociology and evolution theory with earth. We already are the result of the "von Neumann probe".<p>We are not seeing any other aliens because our creators (not god, but some aliens) are so powerful that they destroyed them or kept them away.<p>Well, just a random thought I had after reading the article.

They became smaller. Found a galaxy in every atom and started colonizing them. Life on the micro-level is fun because the speed of light is relatively huge.<p>They became faster. Foreseeing the heat depth of the universe, they invented a way to squeeze an eternity of subjective time into a second of real time, and stayed there. Or turned around in time. Or started oscillating back and forth in the same time interval.<p>They invented wish control, eliminated the survival instinct and went extinct.<p>They contacted God and ascended.

Possible filters:<p>1. The singularity. (Though that begs the question: Why wouldn't robots be observable? Perhaps they exist at a largely "virtual" level, as code, even as they replace life.)<p>2. Dysgenics, aka, Idiocracy. At some point, it may be evolutionarily advantageous to <i>not</i> become more advanced. This is certainly true at present, on average, though the distribution of intelligence is becoming bimodal. The actual filter might ultimately involve a great genocide by Morlock-esque creatures.<p>3. Gamma ray bursts. Could wipe out millions of civilizations all at once.<p>4. Ice nine. This is the author's suggestion, basically. Some sudden discovery that wipes out humanity too quickly for us to recover.<p>....certainly, the author is correct in observing that there are no intelligent aliens, nor could they hide themselves unless they purposefully disabled every radio transmitter for the duration of their hiding.<p>ED: The wiki article is actually pretty good: <a href="http://en.wikipedia.org/wiki/Fermi_paradox" rel="nofollow">http://en.wikipedia.org/wiki/Fermi_paradox</a>

I've thought about this issue in the past and have a similar view to the author's, forgive me if it's a little bit childish:<p>I believe that in order to develop space technology a species(let's call it that) has to be technologically advanced but in order to be technologically advanced the specieshas to be innovative and competitive.<p>But competition is the trait that can cause conflict and wars so any species that has the capability to colonize foreign worlds also has the ability to annihilate itself.<p>Thus I have this idea that every species that has been able to get this technology has killed itself off. It's a morbid view but just an idea that I have.<p>What I like to think is that we are getting more and more in line with nature and less and less pugnacious so at one point maybe we'll get along with the world - hopefully these advanced aliens have reached that point.

If we are the only ones, I find that incredibly scary. We are incredibly more precious than we thought. The fate of all intelligent life rests on this one tiny speck.<p>I, for one, hope that we aren't the only ones, because if we fail, then its all over. If there are more, intelligence will be able to carry on.

The only real paradox on this matter is that UFOs are systematically out ruled as the expected manifestation of ETs.<p>There is apparently a prejudice on what an ET manifestation should or might be. If there is no match, people mistakenly conclude that ET don't exist instead of calling back into question their assumptions on what an ET manifestation should be.<p>Most reasoning about ET naively project humans constrains or interests on them as well as our rationale. This is quite naive.<p>The author suggest filters, I suggest barriers.<p>The most important barrier is interstellar travel which requires to be able to collect energy somehow during the travel (i.e. from dark matter) or the be able to completely freeze any activity and energy spending on board during the travel (i.e. as do plant seed) and using the destination sun as energy source to trigger to reactivation.<p>When a civilization has reached this stage, he most probably has become independent of the need to be on firm ground like an earth or so. He will be much more comfortable in a fully artificial, customized and big enough space ship. What I mean to say is that their constrains may be totally different than what we may expect based on our experience.<p>From this perspective I assume the real value (St Graal) is scientific and engineering knowledge and mastering, and for this, if avoiding direct contact and obvious manifestation can simplify the task, they'll do it.<p>We have no idea on their constrains, their knowledge and how humans are positioned regarding it.<p>There are enough facts and data on UFOs however to learn and deduce things about their technology. (i.e. electro magnetic propulsion, very intense magnetic fields, supra conductive vehicle shell at room temperature and above, protecting against magnetic field, etc...). These are not just speculations, there are hard facts justifying them. (i.e light polarization due to intense EM field around the UFO made visible on a photograph), etc.<p>Apparently very few people really take the time to investigate objectively and in detail the data at hand and the hard facts.

What difference would it make if there <i>were</i> extraterrestrial life?<p>How would an advanced Alien intelligence view human beings, who exploit and slaughter intelligent life around them on a daily basis, including other human beings, and helpless animals who they raise under torturous conditions and then dismember while conscious in order to consume them -- needlessly, as our physiology does not require animal products.<p>Not to mention the warmongering, as the majority of the U.S. public supported war -- as long as it seemed convenient. No anti-war stance on principle for most U.S. citizens, bogglingly, especially after the lessons of Vietnam.<p>A lack of human rights or environmental laws in the most populous country on Earth.<p>Widespread environmental destruction, wiping out forests and ecosystems all over the globe.<p>I don't think Aliens would be too impressed with humanity in general, including SETI researchers who retire to the cafeteria for a nice plate of murdered intelligent being on a daily basis.

<a href="http://www.exitmundi.nl" rel="nofollow">http://www.exitmundi.nl</a> is a great collection of the Great Filter candidates.

Nick mentions Environment Disaster as a possible existential risk, but perhaps the environment is a more mundane and yet still 'Great Filter' that befalls expansionist civilisations.<p>What if the resources required to leave the home planet (including here the resources required for generations of technological steps to reach that point) are more than an Earth-like planet can sustain? In other words, of necessity or as close to it as probability allows, intelligent life must destroy the sustainability of its home planet before it achieves the technology capable of leaving it.<p>Of course, by leaving it I'm talking on the scale required to explore and interact with neighbouring solar systems, not just sending Voyager 1 out there with a picture on its side.

If we're going to posit extraterrestrial life, I'd view the fact that they've stayed hidden from us as a de facto sign of intelligence. "Smart enough to stay the fuck away" sounds like a good start, to me.

I believe that the author makes one fundamental mistake: Assuming that there is one great filter, and that its common across all civilizations. It seems to me there are a large number of filters, some of which applied (to dinosaurs, for example). Some filters may cause end of all life (on earth), some others may simply eradicate all human life..<p>Either way, on a cosmic scale, all this is beyond our control (I'd worry about the sun going nova some day, but I have more pressing things to do), so not much point worrying about it.

I think there's another possibility: advanced civilizations exist, but since they're not malevolent (if they were, we wouldn't exist by now), their ethics prohibit "disturbing" us in the slightest bit, including via the knowledge that there are others out there. So they take care to camouflage themselves when they visit.

I'm not sure if Marconi or Tesla could detect WiMax signals. Of course, that's only 100 years, no telling what a thousand or a million years of tech could hide in the EM spectrum.<p>Also, stuff like nanopond makes me want to think self replication is easier than he's making it out to be.

I think that finding extraterrestrial life would challenge many of the worlds popular religions. Take Christianity for example. How will Christians interpret Genesis after the discovery of life on other planets? Was Christ sent to other planets as well?