Stephen Hawking worries about extraterrestrials (ETs) conquering Earth if we try to contact them. These concerns are indeed justified – though not primarily because of possible colonization in order to exploit Earth's resources or enslave humans. There is another and more pernicious motivation, namely ideological – especially religious – delusion. If ETs were to visit earth, it is likely that they would be fanatical fundamentalists wanting to proselytize. If religious delusion is widespread, demographically expanding and perhaps even of evolutionary advantage, it is a threat to all peaceful sentient beings. This might even offer a solution to Fermi's paradox: ETs are not here, because if they were, we wouldn't be.

Key Words: alien life, astrobiology, extraterrestrial intelligence, SETI, extraterrestrial contact, Fermi's paradox, religion, religiosity, evolution, evolutionary psychology, natural selection, cultural studies, Stephen Hawking, Geoffrey Miller, Richard Dawkins

1. Why Worry?

Stephen Hawking has repeatedly warned against transmitting messages into the sky with a view to contacting extraterrestrial civilizations (Hawking 2002, p. 65; Hawking 2010). And he once presumed that the first contact, if it had happened, would have been recognized easily because of its similarity not with the movie E.T. but with Independence Day (Hawking 2001, p. 179). Though not a specialist in these issues, Hawking is an eminent cosmologist and one of the most famous scientists of the 21st century (Vaas 2005a, 2008a), thus his influential opinion makes a difference. It is praiseworthy that he brought up again a worry about a possible contact with extraterrestrials (ETs), though his opinion should not be confused with – and was not meant as – a scientific statement. Such a contact, although eagerly awaited by some, could turn out to be a disaster in human history. "We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet," Hawking (2010) said. "If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the American Indians."

But is this worry justified, and in what respects? Why should extraterrestrial civilizations want to conquer Earth?

2. Escape or Extinction

Of course it is an open issue whether extraterrestrial life (Cosmovici, Bowyer & Werthimer 1997; Goldsmith & Owen 2001; Horneck & Baumstark-Kahn 2001; Ward & Brownlee 2000) and in particular extraterrestrial intelligence (Drake & Sobel 1992; Shostak 2003a; Vaas 1993, 2003), exists in the Milky Way or in the entire cosmos. But if it does, it is still a matter of controversy whether extraterrestrial civilizations would be numerous, motivated and advanced enough to communicate with us, let alone to meet us (Vaas 2002a; Zaun 2010). They might well be isolated in space and time, and because of the finite velocity of light it would be barely possible to start a dialogue even with our closest neighbors in the course of a human lifetime, let alone to chat.

Moreover, if there is no feasible way to travel faster than light, via wormholes for instance (Visser 1996, Vaas 2005a), a flying visit seems rather unlikely. But nevertheless generation ships, still mostly a topic of science fiction, are technologically possible in principle and might travel through space for millennia (Savage 1992). And because both planetary resources and the lifetime of stars are limited, any advanced civilization is condemned someday either to die out or to leave its home planet – i.e. to settle in outer space or to move to other, younger stars and planets. This is a kind of cosmic imperative. On Earth, for example, we anticipate only another 500 to 1500 million years of moderate temperatures, i.e. a much shorter time than that until our sun blows up to become a red giant star, engulfing Earth in 7.6 billion years (Vaas 2007a; Schroeder & Smith 2008). Thus, planetary escape might very well be underway already, with extraterrestrial civilizations colonizing the galaxy right now (Ulmschneider 2003).

"I imagine they might exist in massive ships, having used up all the resources from their home planet," Hawking speculated. "Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach." This is certainly possible. But there are probably millions of Earth-like planets in the Milky Way (e.g. Franck et al. 2001; von Bloh et al. 2009), and many more planets, dwarf planets, and asteroids to exploit. Thus, if ETs don’t need Earth to survive, if they respect complex, self-conscious life, and if they are not only technologically but also ethically advanced, they would not wipe us out. Nor is it likely that they would just come to eat us and other terrestrial animals, because even if they could digest us it would be much less effort to breed their food, for example in space colonies, than to travel dozens or hundreds of light-years. Equally, cosmic slavery is improbable, for technologically superior intelligences would create robots to deal with hard and stupid work.

So perhaps we should calm down and relax. But this does not imply that we should be trying to establish contact. Firstly, it is much too early and too costly right now, and secondly there are other risks.

3. Already Discovered?

Without a doubt, trying to be silent is only approximately possible – it is a matter of quantity, not quality. And for a simple reason: Earth has already spoken to the stars. This happened not primarily by intention, and the couple of radio messages containing symbols that were transmitted into outer space – the first consisting of 1679 binary digits sent with the power of 1000 kilowatt-hours from the Arecibo observatory on November 16, 1974 in the direction of the globular cluster M13 in the constellation of Hercules – are negligible. But radio was invented at the end of the 19th century, and large-scale broadcasting began in the 1920s. These early transmissions, however, were of low power and at low frequency, thus had difficulty making it into space because they were reflected by Earth's ionosphere. But as early as in the 1930s amateur radio, radio, and television programs started leaking into outer space. These were augmented later by radar signals for both for terrestrial and astronomical purposes. Thus Earth has been broadcasting for decades, and if there is anybody out there, those extraterrestrial civilizations may soon discover signs of our technological existence or have already done so. And perhaps they concluded that there is no intelligent life on earth, judging from TV soap operas, advertisements, and speeches of politicians like the madman opening the Olympics in Berlin 1936, as so powerfully visualized by Robert Zemeckis in his film adaptation of Carl Sagan's novel Contact in 1997.

This should not be overestimated, however. A modern TV transmitter can put out a megawatt of power. It is not very tightly focused, so even though much of the broadcast energy spills into space, it’s fairly weak by the time it reaches another star system. Seth Shostak (2003b) put it in perspective: "Consider one of our early TV programs just washing over a planet that's 50 light-years away. To detect the "carrier" signal from this broadcast in a few minutes time would require about 3,000 acres of rooftop antennas connected to a sensitive receiver. That’s a lot of antennas, and an unsightly concept. But it’s not hard to build, and the aliens could conceivably do it. If the extraterrestrials were unwise enough to actually want to see the program, then they’d need an antenna about 30,000 times greater in area (roughly the size of Colorado). Ambitious, but possible." But their chances dropped since the invention of cable TV.

A rather easier task would be the detection of military radars. The bigger ones typically boast a megawatt of power, and they are focused into beams 1 or 2 degree across. There are enough such radars that they cover about 1 percent of the sky at any given time. "The signal from the most powerful of these could be found at 50 light-years distance in a few minutes time with a receiving antenna 1,000 feet in diameter", Shostak (2003b) estimates. "These military radars are the only signals routinely transmitted from Earth that are intense enough to be detectable at interstellar distances with setups equivalent to our own SETI experiments. With radio technology slightly more advanced than our own, Homo sapiens is detectable out to a distance of roughly 50 light-years. Within that distance are about 5,000 stars, all of which have had the enviable pleasure of receiving terrestrial television. And each day, a fresh stellar system is exposed to signals from Earth." On the other hand it seems quite unlikely that another civilization exists within only 50 or 100 light-years. But this does not mean that Earth is not within the focus of alien observers. "We're no doubt listed in some alien grad students data tables as a world with life, but without the footnote indicating intelligent life", Shostak (2003b) joked. "We are the new kids on the block, and so far it’s a safe bet that none of the other kids know we're here." But they would know that Earth is alive because it displays a great many biological indicators, for example atmospheric spectral signatures indicating that there is organic activity on the planet (oxygen, methane etc.). In that respect, advanced civilizations could have known for up to 2 to 3 billion years that Earth is a habitable planet. So there are expanding cultures out there, why didn't they visited or colonized Earth already?

This is one of the reasons for asking: Where are they? Why, if they are common, haven’t any ETs contacted or visited us already? (There is a vast literature on this issue, known as the Fermi Paradox after Enrico Fermi's famous question "Where are they?" in 1950, cf. e.g. Zuckerman & Hart 1995; Webb 2002; Vaas 2010a.) So do they have no interest, or are they not able to come, or are they simply not out there? In view of these questions, Hawking's worries might appear greatly exaggerated. This is not the case, however, because there are other things that may attract ETs apart from colonization needs. Here one of these shall be briefly sketched, thereby giving a genuine reason to fear an invasion from outer space and another justification for Stephen Hawking's worry.

4. Interstellar Proselytization

It is important to keep in mind that an active attempt to contact ETs, CETI (Communication with Extraterrestrial Intelligence) instead of SETI (Search for Extraterrestrial Intelligence), is not the same as the passive and involuntary signs of Earth's biological activities: First the signals would (have to) be much stronger, and second they indicate our willingness to meet the aliens. This makes a difference, because exactly this can motivate some ETs to visit us – if they are eager to exploit not our resources but our minds: The most severe danger is not that ETs want our planet or our bodies – but that they want our souls.

Though it is unlikely that souls exist as entities ontologically distinct from bodies, for instance as ghostly Cartesian egos (Vaas 1999a & 2002b), it remains likely that there are intelligent beings who believe in the existence of such entities, just as many of our fellow humans still do. On Earth quasi-schizoid attitude systems such as hightech engineering abilities going hand-in-hand with old-fashioned belief in creationism are relatively common too, even in technologically advanced civilizations like the United States of America.

Thus it is a real possibility that alien astronauts would like to visit us for reasons of interstellar proselytization; and no belief in Cartesian dualism is necessary for this, of course – the ETs might hold convictions we can hardly imagine. This sounds like science fiction, but there is already some scientific evidence right here on Earth, i.e. some examples and arguments from evolutionary psychology and sociology.

4.1. Extraterrestrial Theologies – and Religions as Cosmic Universals?

Though there were some considerations about theological implications of ET contacts (cf., e.g., Dick 2005, Kather 2004), speculations about the opposite, extraterrestrial theologies, are quite rare. Of course there is no reason to assume that religious belief is a psychological necessity of and for intelligent beings. Even if humans are "born believers", and this is what some scientists claim (Kelemen & DiYanni 2005; Bulbulia 2007) though the validity of the idea is disputed, and even if religiosity is an evolutionary by-product of an adaptive trait (cf. Boyer 2008; Pyysiäinen & Hauser 2010; Sosis 2009; Vaas 2009bc, 2010c), such circumstances would not imply that every sentient, selfconscious being is affected by these urges of transcendence. Most ETs might never have developed naïve belief systems or simply skipped such forms of psychological projections, wishful thinking, and subtle manipulation, especially due to scientific and social progress, secularization and enlightenment. But, on the other hand, there remains the possibility that there are some ultra-religious aliens out there. Religion might not be a cosmic universal – whether or not it is a human universal (Antweiler 2007; Brown 1991) – but a few devout populations might be enough to fill not the heavens but the sky.

4.2. The Great Temptation

It is rather speculative to think about the future of civilizations, especially extraterrestrial ones, yet a consideration of their underlying psychological, biological, and cultural constraints may be illuminating. Perhaps technologically advanced intelligence has a tendency to be self-limiting, even self-exterminating – either due to its owners’ evolutionary inheritance (becoming maladaptive because of the radically changed environment and dangerous technical abilities) or because of ecological and social problems. Furthermore, advanced civilizations, though they might not blow themselves up, could become trapped in diverse kinds of stagnation, for instance spirituality or addiction to entertainment, thus losing interest in space exploration. This is what Geoffrey Miller (2006) conjectured from the perspective of evolutionary psychology: "They forget to send radio signals or colonize space because they’re too busy with runaway consumerism and virtual-reality narcissism. They don’t need Sentinels to enslave them in a Matrix; they do it to themselves, just as we are doing today. Once they turn inwards to chase their shiny pennies of pleasure, they lose the cosmic plot. They become like a self-stimulating rat, pressing a bar to deliver electricity to its brain’s ventral tegmental area, which stimulates its nucleus accumbens to release dopamine, which feels … ever so good."

Evolution cannot anticipate novel environments. Modern society is such a novel environment. But it is possible for brains to evolve short-cuts: fitness-promoting tricks, cons, recipes and heuristics that work, more often than not, and under different conditions. Adapted to ancestral ecological and social environments, these short-cuts can go astray however. Evolved minds, such as those of higher primates, pay attention to indirect signs of biological fitness rather than tracking fitness itself. Thus, although evolution favors brains that tend to maximize fitness – as measured by numbers of great-grandchildren, for instance, not just direct offspring –, no brain capacity suffices to do so under every possible circumstance, because this would be computationally intractable. And here comes the problem: Modern society can fool the adapted minds and brains because fitness-faking technology tends to evolve much faster than the psychological resistance to it.

Geoffrey Miller (2006) argued, "that a certain period of fitness-faking narcissism is inevitable after any intelligent life evolves. This is the Great Temptation for any technological species – to shape their subjective reality to provide the cues of survival and reproductive success without the substance. Most bright alien species probably go extinct gradually, allocating more time and resources to their pleasures, and less to their children. They eventually die out when the game behind all games – the Game of Life – says ‘Game Over; you are out of lives and you forgot to reproduce.’"

Thus there might be a bottleneck in social evolution if reproduction falls below a certain threshold – though the other extreme, exponential population increase, seems a more imminent and much more serious threat, so this must be brought under control first. Civilizations overcoming those bottleneck(s) will solve the fitnessfaking problems. This might happen not only sociologically, but perhaps even biologically.

Miller (2006) speculated about the latter: "Heritable variation in personality might allow some lineages to resist the Great Temptation and last longer. Some individuals and families may start with an "irrational" Luddite abhorrence of entertainment technology, and they may evolve ever more self-control, conscientiousness and pragmatism. They will evolve a horror of virtual entertainment, psychoactive drugs and contraception. They will stress the values of hard work, delayed gratification, child-rearing and environmental stewardship. They will combine the family values of the religious right with the sustainability values of the Greenpeace left. [...] Those practical-minded breeders will inherit the Earth as like-minded aliens may have inherited a few other planets. When they finally achieve contact, it will not be a meeting of novel-readers and game-players. It will be a meeting of dead-serious super-parents who congratulate each other on surviving not just the Bomb, but the Xbox."

4.3. Explosive Ideologies and Population Explosion

But this sounds much too optimistic, even for Xbox abstainers. If reproductive outnumbering is what counts in evolution, ecological sustainability can hardly be maintained. Moreover, reproductive surplus is usually at the expense of others of the same, or other species. So it is doubtful whether such a meeting of "super-parents" would happen peacefully with mutual congratulations. Furthermore, it is not necessary that the resistance to the "Great Temptation" should be inherited, certainly not directly. Cultural habits and social pressures might be sufficient to preserve it. In any case, unbounded reproductive priorities will shape the course of civilizations, and they accompany or are intended by ideological superstructures, especially religious ones. On Earth, at least, this is clearly the case. Here adherents of fundamentalist religions have, on the average, more children than moderate religious and secular people (reviews in Vaas & Blume 2009, Kaufmann 2010), welfare and educational levels considered. If these additional offspring continually outnumber those turning away from the religion, the fraction of fundamentalist people would steadily increase, in spite of secularization – especially if levels of social injustice, correlated with religiosity and perhaps even abetted by it (Vaas 2010d), are high. Thus fundamentalist ideologies, especially self-immunized religious ones, are likely to sustain population growth despite fitness-faking distractions. If so, expansionist extraterrestrial civilizations are probably religious hardliners.

Their ecological challenges, of course, remain. But here fundamentalist religious doctrines might also be relevant. There are some indications that they foster and strengthen cooperation due to social control, diminishing the influence of free riders (who always undermine reciprocal altruistic cooperation), and thus at least partly solve problems such as the "Tragedy of the Commons" (cf. Irons 2001; Sosis 2004 & 2005; Vaas 2007bc; Schloss 2008).

Thus, one might even put religiosity into a broader perspective. Though religious beliefs seem not to be true (there are powerful arguments that they are wrong, see e.g. Blackford & Schüklenk 2009; Everitt 2004; Martin 2007; Stenger 2007) and even confused mind and brain states (Brüne 2009; Persinger 1987; Urgesi et al. 2010) or just emotions and projections (Epley et al. 2009; Harris et al. 2009; Vaas 2005bc, 2010b) or overactive pattern recognition mechanisms leading to superstition (Hood 2009), they have effects. And these effects could be a by-product of adaptive traits (obedience to authority, pseudo-explanations, superstition) or even have a more direct evolutionary advantage with regard to natural selection by fostering cooperation or improving health, or in relation to sexual selection (see Vaas 2006a, 2009bc; Bulbulia 2008; Vaas & Blume 2009; Voland & Schiefenhövel 2009 for detailed critical reviews and discussion).

Furthermore, many fundamentalist religions are expansionist. As the Pilgrim Fathers, the Mormons and many others on Earth explored and populated new and even harsh environments, religious ETs might also be colonizing outer space to cope with their population increase. And they most likely feel themselves called upon to "spread the word" if they are able – perhaps even beyond their own species. Thus if they happen to receive contact calls from Earth, they might soon visit us in search of new followers and believers. And if we do not follow and believe, they might bring us their "truth" with fire and sword…

4.4. Shall the Religious Inherit the Milky Way?

Of course, no single step in this sketch of extraterrestrial cultural development is necessary and self-evident. But if it were to take place it might be self-sustaining and self-enforcing, leading to social and perhaps even biological selective advantages. The latter, depending on genetic constraints, are more controversial (cf. Vaas 2005d for spirituality), but need not to imply specific genes "for religiosity" – religiosity might simply be a by-product or "parasitic meme" based on other traits such as obedience to authority (Bouchard 2009, Vaas 2010d).

Summing up, fundamentalist belief-systems could be a driving force for cultural proliferation, interstellar expansion included. If such fundamentalist doctrines are successful, and as an object of cultural (or memetic) selection (Dawkins 1993) they very well could be, then they even might cross the borders of species. Thus one can imagine expanding extraterrestrial civilizations that are driven by religious doctrines and occupied with a cosmic kind of evangelization – the extreme case being that invaded inferior civilizations either subscribe to those doctrines or simply get eradicated.

Such a scenario is not that speculative. On Earth there are many small-scale examples of it. (Of course religion is not the only such driving force.) Indeed the colonization and subjugation of the Americas, which Stephen Hawking also mentioned, was driven by a complex interplay of economical, political, military and religious factors. And this is just one example. Furthermore, such struggles are continuing globally, and future clashes of civilizations are probable. Reproduction rates of fundamentalists such as Christian Pentecostals, radical Muslims, orthodox Jews and also lesser known, much more peaceful groups such as the Amish and the Hutterites are high. Therefore perhaps this "breeding for God", as Stuart Kaufmann (2006 & 2010) calls it, implies that "the religious shall inherit the Earth". This tendency can be combined with Geoffrey Miller’s view. He pointed out (2006) that "Christian and Muslim fundamentalists and anti-consumerism activists already understand exactly what the Great Temptation is, and how to avoid it. They insulate themselves from our creative-class dreamworlds and our EverQuest economics. They wait patiently for our fitness-faking narcissism to go extinct."

Religious convictions might not be psychologically necessary. But, on the other hand, neither is it a necessity that all advanced civilizations abandon strange, non-verifiable beliefs in transcendent entities. Just a few of them would be enough to conquer the galaxy if sufficiently motivated. And more peaceful, wiser secular civilizations might be completely at the mercy of their spiritual and accompanying military attacks. An obviously increasing threat here on Earth too.

In conclusion, it is likely that if ETs visit Earth, interstellar proselytization will come with them. Thus they might force us to make a choice between complete subjugation or becoming extinct. (It would be a galactic version of the "cuius region, eius religio" rule: "whose realm, his religion".) It is also possible and even more alarming that the dominant fundamentalist doctrine may be based on a uniqueness dogma claiming superiority of the adherents and a dualistic good / evil scheme: a cosmic Armageddon. So if these devotional civilizations spread "successfully" in this manner, mankind, standing in their way, will simply be thrown aside from the road of salvation, like all dissenters. The winner takes it all.

4.5. The Hazard of Faith

All these considerations might appear far-fetched. But they aren't. We have these same problems and hazards right here on Earth at present, albeit on smaller scales. But if we cannot and will not hold the ideologists at bay, they will sooner or later devastate our own planet or at least the fruits of our scientific and philosophical cultures long before frenzied aliens will do.

Religiosity and religions are not always, and not in every case, devastating, of course. But because of their inherent tendency to claim infallible truth and even absolute relevation, in the extreme immunity to any criticism, they carry the evil seeds of intolerance (Dawkins 2006a; Grayling 2007; Hitchens 2007; Persinger 1997). This may go as far as condoning killing of all non-believers – or at least opening the door for such (mis)use by fanatics, and allowing those greedy for power to exploit them for their own purposes.

Even if religion was useful or advantageous in the past, it might be harmful and detrimental nowadays or in the future. The main problem is that ideological dogmas – and there are not only religious ones! –, claiming to own absolute, infallible truths, can and often did motivate people to dehumanize and debase others. As Steven Weinberg (2001, p. 174) once wrote: "with or without religion, good people would tend to behave well and bad people would do evil things, but the peculiar contribution of religion throughout history has been to allow good people do evil things."

It is religious ideology or, according to people like Richard Dawkins (2006a), religious delusion, i.e. madness, which provides a strong motivation for galactic colonization and the concomitant cosmic dangers. In certain social contexts, religious doctrines (i.e. mind or brain states, not free-floating ideas) can act as powerful motivational forces (meant as a heuristic description without ontological implications or connotations); this should not be underestimated or considered only with respect to Earthly circumstances. And that seems also to be the main justification for, and applicability of Stephen Hawking's warning. It is interstellar proselytization, combined with avarice and inclemency, which we should fear most – and for which there are numerous examples in human history. As Richard Dawkins once wrote (2006b, p. 330 f): "Faith cannot move mountains (though generations of children are solemnly told the contrary and believe it). But it is capable of driving people to such dangerous folly that faith seems to me to qualify as a kind of mental illness. It leads people to believe in whatever it is so strongly that in extreme cases they are prepared to kill and die for it without the need for further justification. […] Faith is powerful enough to immunize people against all appeals to pity, to forgiveness, to decent human feelings. It even immunizes them against fear, if they honestly believe that a martyr's death will send them straight to heaven. What a weapon! Religious faith deserves a chapter to itself in the annals of war technology, on an even footing with the longbow, the warhorse, the tank, and the hydrogen bomb." – Why should extraterrestrial faith be any better in these respects?

5. Discussion

It is not claimed here that ETs who inhabit the Milky Way and want to contact or visit us are necessarily malevolent. On the contrary, there are also arguments suggesting that advanced civilizations should be peaceful and wise, otherwise they would have blown up themselves before colonizing space (cf. von Hoerner 2003). Thus there could be a kind of self-deselection of aggressive, destructive character traits. But this is not necessarily the case. Even if there is only one species, or just a small minority, its individuals, driven by strong ideological motivation, these alien beings might spread out across the whole galaxy if nobody can or wants to stop them.

5.1. SETI Yes, CETI No

So Stephen Hawking's worries are justified: We should indeed not actively try to contact ETs because the risks are still much higher than the potential gains, and we have a lot to lose. However, this does not mean we should abandon the Search for Extraterrestrial Intelligence. On the contrary, SETI gains a further justification. It is not only basic research that might help us to better understand life and our place in the universe. It is also pre-emptive defense. If there are ETs in our neighborhood, already detectable within the limits of our current technology, we had better watch out and be prepared for contact, however and whenever it comes. At the moment it is certainly better to stay silent.

If ETs are out there, they have probably spotted us already, or will soon do so. And they should be technologically more advanced (otherwise there is no need to fear them). Because of this, it should be much easier and cheaper for them to contact us. Direct messages are far more effective than all-sky transmissions. And we do not know where to send our messages.

In any case it is much too early to broadcast. We know almost nothing about what is going on in outer space (if anything); we have just begun to explore radio frequencies and only recently started some searches for optical (i.e. laser) signals; but ETs might use completely different and much more effective channels like neutrinos, axions, or gravitational waves, which are still completely beyond our reach. Thus, until SETI, in its listening mode, is much more advanced than today and until we have scanned most of the sky at many different wavelengths, it is not only to early but also downright naïve to beam messages into the sky. Searching, i.e. listening, is good and important, but calling for contact, i.e. transmitting, is not. By the way this is also Stephen Hawking's position (2002, p. 65).

5.2. Accidental Existence

One of the most remarkable developments in human cultural history was the recognition of our tiny place in the vast universe (or perhaps multiverse), and that we are not obviously meant to be here. The overcoming of a naïve and infantile anthropocentrism, that the universe is there for us, and, strangely connected, that an all-compassing god is there for us too (and vice versa) was one of man's great – and still not fully accomplished – achievements: an "emergence from his self-incurred immaturity" (Immanuel Kant). Darwinian theory of evolution suggested that man, and indeed life itself, was not ingeniously designed, but a result of self-organizing processes, a "fruit of chance and necessity", as Jacques Monod (1970) used to cite Democritus. Astrophysics, big bang theory and, finally, the still speculative scenarios of quantum cosmology (cf. Vaas 2009a, 2010ef) taught the same lesson albeit on much larger scales: The emergence of intelligence was more or less an accident, not meant to be there in a universe that is indifferent to life's concerns, goals and values. However, in intelligent, self-conscious beings like humans the universe at least became partly aware of itself, poetically speaking.

But self- and I-consciousness also revealed the absurdity of life in the face of chance, futility and misery (Vaas 1995, 2006b & 2008b). The shirking of belief in transcendent creators or in an almighty, omnibenevolent god, though perhaps consolatory for some, cannot surmount absurdity because misery, injustice and death would be even more scandalous, thus antitheism should be the natural reaction (Vaas 1999b). Anyway, it is hard to accept for intentional, goal-oriented beings to regard the sometimes sophisticated structures of nature as the result of "blind" self-organized processes. Although exactly this is the scientific approach casting out any exigencies for design assumptions or teleological explanations, psychological resistance might prevent ETs from accepting it – as it is common here on Earth too.

5.3. Another Solution for Fermi's Paradox

One might object that interstellar proselytization would be no danger but a kind of cosmic first aid – perhaps even saving us from self-destruction. Or taking ancient astronaut theories more seriously than they deserve, one might even speculate that extraterrestrial mission has already been tried on Earth. For example in their book Intelligent Life in the Universe Iosif Samuilovich Shklovskii and Carl Sagan (1966) devote a chapter to the suggestion that historians and scientists should take into account the possibility that extraterrestrial contact occurred during prehistory or recorded history. Shklovskii and Sagan stressed that these ideas were entirely unproven. But it is not absolutely impossible that cosmic Evangelists have already appeared and seeded Earth with "viruses of the mind", as Richard Dawkins (1991) characterized religious ideas.

Such considerations, however, are beyond the scope of this argument. Under certain conditions religions and proselytization might or might not be beneficial. But as aggressive ideologies they would not. And this is the threat Hawking worries about – a threat nobody should deny or minimize. After all mankind's history has many examples of missionaries, the Crusades, the Conquistadors, the Inquisitions, and so on, being sent to convert other people or to kill them if they do not comply with the ideology (cf., e.g., Burman 2004; Holt 2005, Innes 2002; Schwerhoff 2004). One can also object that interstellar proselytization might threaten our freedom, but not our lives – because dead bodies cannot be converted – but who knows…? However, this could be proved wrong, not only by cosmic Armageddon doctrines – restricting freedom is necessarily life-threatening, at least for some people. And even if interstellar Evangelists chose not to kill or enslave us, do we really want to be brainwashed once more by obscure doctrines, as has happened already throughout much of human history and still happens today? We should resist false promises, metaphysical shirking and cowardice. And we should stand up for a secular naturalism including the ultimate absurdity of life and tragic individualism (Vaas 2008b); it might sound uncomfortable, but at least it seems honorable, honest, and true.

If we take the idea of potentially life-threatening interstellar missionaries seriously, and it was argued here that we should, this idea could even offer a (weak-anthropic-principle- like) solution (cf. Vaas 2004) to Fermi's paradox: ETs are not here, because if they were, we wouldn't be.

Acknowledgments and dedication: It is a pleasure and honor to thank Angela Lahee for very helpful and timely comments and suggestions. Thanks also to Jill Tarter and Frank Drake for an inspiring contact years ago, to Jenny Wagner for discussion, and to André Spiegel for an important reference. – This paper is dedicated in memoriam to Sebastian von Hoerner, though he probably would have been skeptical about parts of it; for me it was always a pleasure to discuss with him and to learn from him as well as sharing the experience of radio astronomy, especially at the Green Bank Observatory.

Blackford, R., Schüklenk, U. (eds.) (2009). 50 Voices of Disbelief. Chichester: Wiley- Blackwell.

Bouchard, T. J. (2009). Authoritarianism, Religiousness, and Conservatism. In: Voland, E., Schiefenhövel, W. (eds.) (2009). The Biological Evolution of Religious Mind and Behavior. Heidelberg: Springer, 165-180.

Boyer, P. (2008). Being Human. Nature 455, 1038-1039.

Brown, D. E. (1991). Human Universals. New York: Temple University Press.

Brüne, M. (2009). On Shared Psychological Mechanisms of Religiousness and Delusional Beliefs. In: Voland, E., Schiefenhövel, W. (eds.) (2009). The Biological Evolution of Religious Mind and Behavior. Heidelberg: Springer, 217-228.

Bulbulia, J. A. (2007). The evolution of religion. In: Dunbar, R. I. M., Barrett, L. (eds.) (2007). The Oxford Handbook of Evolutionary Psychology. Oxford: Oxford University Press, 621- 637.

Bulbulia, J. et al. (eds.) (2008). The Evolution of Religion. Santa Margarita: Collins Foundation Press.

Burman, E. (2004). The Inquisition: Gloustershire: Sutton.

Cosmovici, C.-B., Bowyer, S., Werthimer, D. (eds.) (1997). Bioastronomy. Bologna: Editrice Compositori.

Dawkins, R. (1993). Viruses of the Mind. In: Dahlbom, B. (ed.). Dennett and his critics. Oxford: Blackwell, 13-27.

Dawkins, R. (2006a). The God Delusion. London: Bantam Press.

Dawkins, R. (2006b). The Selfish Gene. Oxford: Oxford University Press, p. 330 f

Dick, S. J. (2005). Kosmoltheologie – neu betrachtet. In: Wabbel, T. D. (ed.) (2005). Leben im All. Düsseldorf: Patmos, 156-172.

Drake, F., Sobel, D. (1992). Is Anyone Out There? New York: Delacorte.

Epley, N. et al. (2009). Believers’ estimates of God’s beliefs are more egocentric than estimates of other people’s beliefs. Proceedings of the National Academy of Sciences 106, 21533-21538.

Everitt, N. (2004). The Non-existence of God. London: Routledge.

Franck, S. et al. (2001). Planetary habitability: Is Earth commonplace in the Milky Way? Naturwissenschaften 88, 416-426.

Goldsmith, D., Owen, T. (2001). The Search for Life in the Universe. Sausalito: University Science Books; 3rd edition.

Grayling, A. C. (2007). Against all Gods. London: Theatre Communications.

Harris, S. et al. (2009). The Neural Correlates of Religious and Nonreligious Belief. PLoS ONE 4 (10), e7272.

Hawking, S. (2001). Das Universum in der Nussschale. Hamburg: Hoffmann und Campe.

Hawking, S. (2001). Leben im Universum. In: Wabbel, T. D. (ed.) (2002). S.E.T.I. München: beustverlag, 53-65.

Hawking, S. (2010). Quoted in: Stephen Hawking: alien life is out there, scientist warns. Telegraph, April 25; http://www.telegraph.co.uk/science/space/7631252/Stephen-Hawkingalien- life-is-out-there-scientist-warns.html

Hawking, S. (2010). Quoted in: Don’t talk to aliens, warns Stephen Hawking. Sunday Times, April 25; http://www.timesonline.co.uk/tol/news/science/space/article7107207.ece

Hitchens, C. (2007). God is not Great. New York: Twelve Books.

Holt, A. (2005). Crusades-Encyclopedia. http://www.crusades-encyclopedia.com/index.html

Hood, B. M. (2009). Supersense. New York: HarperOne.

Horneck, G., Baumstark-Kahn, C. (eds.) (2001). Astrobiology. Heidelberg: Springer. Innes, H. (2002). The Conquistadors. London: Penguin.

Irons, W. (2001). Religion as a Hard-to-Fake Sign of Commitment. In: Nesse, R. (ed.) (2001). Evolution and the Capacity for Commitment. New York: Russell Sage Press, 292-309.

Kather, R. (2004). Gott ist der Kreis, dessen Mittelpunkt überall ist. In: Peitz, H.-H. (ed.). Der vervielfachte Christus. Hohenheim: Akademie d. Diözese Rottenburg-Stuttgart, 17-72. http://www.akademie-rs.de/fileadmin/user_upload/pdf_archive/khr46.pdf

Kaufmann, E. (2006). Breeding for God. Prospect Magazine 128 (11); http://www.prospectmagazine.co.uk/2006/11/breedingforgod/

Kaufmann, E. (2010). Shall the Religious Inherit the Earth? London: Profile.

Kelemen, D., DiYanni, C. (2005). Intuitions About Origins: Purpose and Intelligent Design in Children’s Reasoning About Nature. Journal of Cognition and Development 6, 3-31.

Martin, M. (ed.) (2007). The Cambridge Companion to Atheism. New York: Cambridge University Press.

Miller, G. (2006). Why We Haven't Met Any Aliens. Seed Magazine (4/5), 41-43; http://seedmagazine.com/content/article/why_we_havent_met_any_aliens/

Monod, J. (1970). Chance and Necessity. New York: Knopf 1971.

Persinger, M. A. (1987). Neuropsychological basis of God beliefs. New York: Praeger.

Persinger, M. A. (1997). I would kill in God’s name. Perceptual and Motor Skills 85, 128-130.

Pyysiäinen, I., Hauser, M. (2010). The origins of religion: evolved adaptation or by-product? Trends in Cognitive Sciences 14, 104-109.

Savage, M. T. (1992). The Millennial Project: Colonizing the Galaxy in 8 Easy Steps. Denver: Empyrean Publishing.

Schloss, J. P. (2008). He Who Laughs Best. In: Bulbulia, J. et al. (eds.) (2008). The Evolution of Religion. Santa Margarita: Collins Foundation Press, 197-207.

Schroeder, K.-P., Smith, R. C. (2008). Distant future of the Sun and Earth revisited. MNRAS 386, 155-163; http://www.astro.ugto.mx/~kps/KPSPub51.pdf

Schwerhoff, G. (2004). Die Inquisition. München: Beck.

Shostak, S. (2003a). Cosmic company. Cambridge: Cambridge University Press.

Shostak, S. (2003b). Can Aliens Find Us? Space.com (Oct. 23); http://www.seti.org/Page.aspx?pid=751

Shklovskii, I. S., Sagan, C. (1966). Intelligent Life in the Universe. San Francisco: Holden- Day.

Sosis, R. (2004). The Adaptive Value of Religious Ritual. American Scientist 92, 166-172.

Sosis, R. (2005). Does Religion Promote Trust? Journal of Research on Religion 1, 1-30; http://www.anth.uconn.edu/faculty/sosis/publications/Sosis,DoesReligionPromoteTrust,IJR R.pdf

Sosis, R. (2009). The Adaptationist-Byproduct Debate on the Evolution of Religion: Five Misunderstandings of the Adaptationist Program. Journal of Cognition and Culture 9, 315- 332.

Stenger, V. J. (2007). God: the failed hypothesis. Amherst: Prometheus Books.

Ulmschneider, P. (2003): Intelligent Life in the Universe. Heidelberg: Springer.

Vaas, R. (1993). Sind wir allein im All? Universitas 48, 1174-1190.

Vaas, R. (1995). Masse, Macht und der Verlust der Einheit. In: Krüger, M. (ed.) (1995). Einladung zur Verwandlung. München: Hanser, 219-260.

Vaas, R. (1999a). Why Neural Correlates Of Consciousness Are Fine, But Not Enough. Anthropology & Philosophy 3, 121-141; http://cogprints.org/5810/

Vaas, R. (1999b). Der Riß durch die Schöpfung. Antitheismus als metaphysische Revolte. der blaue reiter, Journal für Philosophie 10, 39-43.

Vaas, R. (2002a). Außerirdische. bild der wissenschaft 2, 44-61.

Vaas, R. (2002b). Der Streit um die Willensfreiheit. Universitas 57, 598-612, 807-819.

Vaas, R. (2003). Die Suche nach außerirdischen Intelligenzen. In: Kneifel, H. (2003). Das Energie-Riff. München: Heyne, 224-286.

Vaas, R. (2004). Ein Universum nach Maß? In: Hübner, J., Stamatescu, I.-O., Weber, D. (eds.) (2004). Theologie und Kosmologie. Tübingen: Mohr Siebeck, 375-498.

Vaas, R. (2005a). Tunnel durch Raum und Zeit. Stuttgart: Kosmos; new edition 2010.

Vaas, R. (2005b). Gott und Gehirn. In: Sahm, P. R. et al. (eds.) (2005). Homo spaciens. Hamburg: discorsi, 181-208.

Vaas, R. (2005c). Hotline zum Himmel. bild der wissenschaft 7, 30-38.

Vaas, R. (2005d). Das Gottes-Gen. bild der wissenschaft 7, 39-43.

Vaas, R. (2006a). Die Evolution der Religiosität. Universitas 61, 1116-1137.

Vaas, R. (2006b). Das Münchhausen-Trilemma in der Erkenntnistheorie, Kosmologie und Metaphysik. In: Hilgendorf, E. (ed.) (2006). Wissenschaft, Religion und Recht. Berlin: Logos, 441-474.

Vaas, R. (2007a). Flammendes Finale. bild der wissenschaft 11, 44-51.

Vaas, R. (2007b). Lohnender Luxus. bild der wissenschaft 2, 34-41.

Vaas, R. (2007c). Schutz vor Schmarotzern. bild der wissenschaft 2, 42-45.

Vaas, R. (2008a). Hawkings neues Universum. Stuttgart: Kosmos; 5th edition 2010.

Vaas, R. (2008b). Aufrechtstehen im Nichts. Universitas 63, 1118-1137, 1244-1259.

Vaas, R. (2009a). Life, the Universe, and almost Everything: Signs of Cosmic Design?; arXiv:0910.5579

Vaas, R. (2009b). Gods, Gains, and Genes. In: Voland, E., Schiefenhövel, W. (eds.) (2009). The Biological Evolution of Religious Mind and Behavior. Heidelberg: Springer, 25-49.

Vaas, R. (2009c). Götter, Gene und Gehirne – Biologische Grundlagen der Religiosität. Die Kunde N. F. 60, 305-322.

Vaas, R. (2010a). Außerirdische – wo seid ihr? bild der wissenschaft 2, 40-47.

Vaas, R. (2010b). Gläubige Gehirne. bild der wissenschaft 1, 54-59.

Vaas, R. (2010c). Der Nutzen des Himmels. bild der wissenschaft 1, 60-61.

Vaas, R. (2010d). Weltangst schürt die Gottesfurcht. bild der wissenschaft 1, 62-69.

Vaas, R. (2010e). Multiverse Scenarios in Cosmology: Classification, Cause, Challenge, Controversy, and Criticism. Journal of Cosmology 4, 666-676; arXiv:1001.0726

Vaas, R. (ed.) (2010f). Beyond the Big Bang. Heidelberg: Springer.

Vaas, R., Blume, M. (2009). Gott, Gene und Gehirn. Stuttgart: Hirzel.

Visser, M. (1996). Lorentzian Wormholes. Woodbury: American Institute of Physics Press.

Voland, E., Schiefenhövel, W. (eds.) (2009). The Biological Evolution of Religious Mind and Behavior. Heidelberg: Springer.

von Bloh, W. et al. (2009). Habitability of Super-Earth Planets around Other Suns: Models including Red Giant Branch Evolution. Astrobiology 9, 593-602; arXiv:0812.1027

von Hoerner, S. (2003). Sind wir allein? München: Beck.

Ward, P. D. Brownlee, D. (2000). Rare Earth. New York: Copernicus.

Webb, S. (2002). If the Universe Is Teeming with Aliens... Where Is Everybody? New York: Copernicus Books.

Weinberg, S. (2001). A Universe with No Designer. In: Miller, J. B. (ed.) (2001). Cosmic Questions. New York: Annals of the New York Academy of Sciences, 169-174.

Zaun, H. (2010). SETI – Die wissenschaftliche Suche nach außerirdischen Zivilisationen. Hannover: Heise.

Zuckerman, B., Hart, M. H. (eds.) (1995). Extraterrestrials: Where Are They? Cambridge: Cambridge University Press.