The Fermi Paradox

The &quot;we are the first&quot; argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at &gt;0.9c. We must assume the same of ET.<p>Now information only reaches us at the speed of light; we are only capable of looking for ET in our own past light cone. That means that any Type I or Type II civilization like us should <i>expect</i> to see an empty sky for most of their existence, until all of a sudden the most distant stars go dim (Dyson sphere, or whatever energy capturing device). And the darkness spreads in a wavefront travelling at <i>almost</i> the speed of light, until it hits and ... the unpredictable happens.<p>We see an empty sky because if the sky wasn&#x27;t empty, the planet we call Earth and our Sun would already be consumed by some extraterrestrial Type III civilization and Fermi would never have existed.<p>[1] An inflationary universe provides incentive for a hypothetical Type III civilization to spread throughout the cosmos as quickly as possible, as idle time means regions of the universe becoming permanently inaccessible. Or maybe just resource competition and a desire for some elements of a population to remain on the frontier.

This article does a good job of covering a lot of different ideas on this paradox. I have a problem with the idea of &quot;big numbers&quot; in it though, like where it implies 500 billion billion is nearly infinite, or that one-in-a-billion is a freak occurrence. There is a saying that if enough monkeys pound on a keyboard, one will type Hamlet. This would take a lot of monkeys. If we take the odds of hitting one character to be 1 in 40 (which doesn&#x27;t account for properly hitting the shift key to make a capital), factoring in the 130,000 letters in Hamlet (according to Wikipedia), we get the odds of a monkey typing it at 6x10^208267. This number comes from 40 keys and 130,000 letters. How about when we start taking molecular numbers of items (6x10^23) and start raising that to a large power? I don&#x27;t think it is a given that the number of planets out there infer there should be other life.

I think Authors is way way optimistic with these numbers:<p>&quot;Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life&quot; and &quot;<p>&quot;And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth&quot;<p>Why 1% and not 10^-10%?

The estimates of stars seem reasonable; the estimates of Earth seem a bit ill-defined. (The study he links to discuses Earth-size planets, but there are many other factors that go into Earth&#x27;s suitability for life.) The real issue though is in the &quot;speculative&quot; part:<p>&gt; Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life... And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. &quot;<p>1% sounds like a small number, but it&#x27;s a bit ridiculous to just throw it out there and assume it&#x27;s reasonable. It&#x27;s a little bit like when a startup does a top-down estimate of revenue - &quot;If we only capture 1% of the e-commerce market, we&#x27;ll be worth billions!&quot;<p>I think if you do a &quot;bottom-up&quot; style analysis of the likelihood of atoms forming a replicating growing organism, or that organism evolving to think intelligently, you would get a far smaller number, say in the range of 0.00001% to 10^-20 for each one.

I&#x27;ve always wondered at what distance it would be impossible for current technology to detect life on earth.

I think the biggest fallacy in this rationalization is when it is assumed that advanced civilizations would want to expand like yeast; consuming everything, building dyson spheres... Why would they want that much energy, and why extract it from the sun? Trying to picture myself as one of these superlifeforms, I think would like to have the sun visible... For sunbathing and sh<i></i><i></i>... plants to grow etc... Maybe they have built little fusion reactors wherever they need energy?

I am surprised a more common argument was not mentioned: other life exists but the laws of physics limit our interaction. Maybe there is undiscovered physics like wormholes or time travel, or maybe there isn&#x27;t and the speed of light really is a fundamental limit that cannot be surpassed. In that case, no matter how advanced another civilization becomes, they still can&#x27;t violate natural law and are thus unable to reach us.

How about the theory that we are the way super-civilization spreads?<p>If physical space travel is extremely expensive (as it should be, considering the distance), then may be it is better to send a signal that would trigger creation of life (in our case on Earth).<p>Then when Earth civilization is advanced enough, it would be able to receive complete boot sequence and then fully advanced alien civilization would be replicated on Earth.

Possibility 5) There’s only one instance of higher-intelligent life—a “superpredator” civilization (like humans are here on Earth)—who is far more advanced than everyone else and keeps it that way by exterminating any intelligent civilization once they get past a certain level.<p>If we&#x27;re the most advanced civilization right now, that will be us in a few million years. We&#x27;re kind of dicks.

In that great expanse and time, there may also have been ample time for civilizations to rise, then fall. We might have just missed them on such grand scales. Nobody says we&#x27;ll be hanging around for a billion years trying to communicate with others... if we even last that long.

We are not even listening hard. SETI covers an incredibly tiny range of possible spectrum and possibilities of intelligent life. Are there any other attempts to find alien communication via data mining?<p>If I were a galactic artist, I would use pulsars to modulate their signals and create a statue that broadcasts the existence of life.<p><a href="http://www.technology.org/2013/11/20/extraterrestrial-civilizations-modulate-pulsar-signals/" rel="nofollow">http:&#x2F;&#x2F;www.technology.org&#x2F;2013&#x2F;11&#x2F;20&#x2F;extraterrestrial-civili...</a>

I personally find the &quot;we are first&quot; solution to be the scariest scenario. We are not suited for the responsibility of being the only intelligent life in the universe.

I don&#x27;t see why a &quot;Great Filter&quot; is needed to justify there being no other highly evolved lifeforms - all it needs is for there to need to be a reasonably large number of key evolutionary steps and environmental conditions with a sufficiently low probability. Multiply those and you end up with some pretty tiny chances of observing life as we know it.

Would discovering the fossils of some complex species on Mars (or any where else in the solar system) be any worse for getting past the great filter then the discovery of fossils of dinosours on earth. We allready know that mass extinction events on Earth are possible, and should expect them to occur on other planents with life too

The idea that maybe aliens visited before humans could record what they experienced struck me. Even if they did record it, we wouldn&#x27;t believe it. Need proof? See the Bible or virtually any other ancient religious text. Our modern society believes if we can&#x27;t prove it today, it didn&#x27;t happen.

I think they sort of cover this but here is my simple explanation. Think about how many slugs there are on Earth. How many of them have never seen a human? If we are slugs in comparison to advanced beings that have a billion years of evolution on us then it is no surprise we have not seen them.

How about this possibility: the Great Filter is now! We entered it, perhaps, when we developed sufficient collective nuclear weapons capability to wipe out most or all human life; we won&#x27;t be out of it until the major threats our civilization poses to the biosphere have been resolved.

My solution to the Fermi Paradox: Who the hell knows, who the hell <i>can</i> know, when all we have is a sample size of 1 to extrapolate from. The solutions to the FP seem to be representative of the personal beliefs of whomever is discussing it.

Thanks for letting me find out about this article and this whole awesome website!

i love this puzzle. here are some theories:<p>1. simulation argument<p>2. civilizations have a high or inevitable chance to self destruct after &lt;1M years of language<p>3. civilizations transcend our observable universe after &lt;1m years [1]<p>4. due to the single observer problem, humans fail to grok some very important feature of larger scale space that prevents detection&#x2F;increases isolation<p>[1] <a href="http://accelerating.org/articles/transcensionhypothesis.html" rel="nofollow">http:&#x2F;&#x2F;accelerating.org&#x2F;articles&#x2F;transcensionhypothesis.html</a>

Think of something like the &quot;Human Brain Project&quot; [1] scaled to what it could become after evolving&#x2F;improving&#x2F;growing for 3.2 billion years..<p>[1] humanbrainproject.eu

I&#x27;m a bit surprised nobody mentioned AI-s taking over as the Great Filter. I&#x27;m sure every technical civilization attempts to do that because it&#x27;s very tempting to accelerate your intelligence by computation.<p>I&#x27;ve also read an interesting article that why probably machine life is more abundant than biological: <a href="http://www.popularmechanics.com/how-to/blog/robot-universe-dominant-lifeform-17549081" rel="nofollow">http:&#x2F;&#x2F;www.popularmechanics.com&#x2F;how-to&#x2F;blog&#x2F;robot-universe-d...</a>

We might be very close to finding life on Mars. If we did and it was different than us that would answer a lot of questions.

when the question is: &quot;where are they?&quot; and the answer is: &quot;there is nobody here.&quot; then all long living civilisations must have left. so we should answer the question &quot;why did they leave?&quot;

Out of all those advanced civilizations in the universe, what fraction use electromagnetic radiation for communication? We are like ants waiting for other civilizations to communicate with us using pheromones.

Another possibility... there are plenty of civilisations within broadcasting distance from us that are all listening but not broadcasting for fear of predatory civilisations.