by Larry Klaes

Larry Klaes wraps up his two-part essay on our attitudes towards extraterrestrials by looking at how the subject has been treated in the past, and speculating on the scenarios that might bring disaster. Do Earth-shattering depictions of space invasion reflect what people really believe, or are they merely a form of escapism? Either way, they tell us something about ourselves as we confront the possibility of contact.

For those who may still wonder and question just how much weight the words of the famous cosmologist Stephen Hawking hold for the concept of alien intelligences and their potential reactions to encountering humanity, consider this: A new science fiction film coming out this November titled Skyline has recently premiered its theatrical trailer, which you can view here. The trailer begins with the line: “On August 28th, 2009, NASA sent a message into space farther than we ever thought possible… in an effort to reach extraterrestrial life.”

Now it is true that a transmission was sent from Earth into deep space on that very date and it was indeed broadcast by a NASA-owned radio telescope located in Australia. However, the collection of messages sent into the Milky Way galaxy from people all over the world as part of the Hello from Earth campaign were aimed at a planet in the red dwarf star system of Gliese 581, which is only 20.3 light years, or 194 trillion kilometers from us. Now that may seem like a long way to Earth-bound humanity, but on a celestial scale the Gliese 581 system is a near neighbor. Besides, the transmission, moving at the speed of light (almost 300,000 kilometers every second), is just over one light year from Earth as of this writing. That isn’t even far enough to reach our closest stellar neighbors, the Alpha Centauri system at 4.3 light years distant, let alone be properly given the title of the farthest human message ever.

As a final point, we are far from certain if any life of any kind exists either on or near the target of Hello from Earth, the fourth world circling the star Gliese 581. However, astronomers now think at least one and possibly three planets in that system have the potential to possess water in a liquid state, a major ingredient for the formation of at least terrestrial types of life. Of course the transmission is not going to stop once it reaches that alien planet. The messages will spread outward and onward into the galaxy at light speed, which will give them an increased chance of being detected some day by an ETI, assuming any exist in the signal path.

Image: Alien devastation in the upcoming movie Skyline. Credit: Universal Pictures.

With this inauspicious beginning to the trailer, the viewer is then treated to some apparently real news broadcasts about Hawking’s alien warnings interspersed with images of strange bluish-white meteor-like lights dropping down upon the city of Los Angeles. In the news segments, former CBS Television news anchor Dan Rather intones that “if extraterrestrials visit us, the outcome might be similar to when Columbus landed in America. In other words, it didn’t turn out too well for Native Americans.” The trailer caps off this dire warning with the text “Maybe we should have listened.” And done what, I have to ask? Cover Earth in black tarp with some stars painted on the outside and hope nobody notices us?

Too late, the alien Columbuses arrive in their bizarre and menacing spaceships over the city, looking like some kind of gothic metal sculptures bearing down on the places where the lights had landed. A quick reveal is made to the audience of the name of this film being advertised and then the final scene: A close-up of one of the alien vessels hovering over LA, its underside open wide like the jaws of some immense beast, pulling thousands of tiny screaming, tumbling humans up through the air and into itself for reasons as yet unknown, but ones the audience has little trouble imagining may not be for the benefit of humanity.

A final text warning suggests that we “Don’t look up”, which is directly counter to what our society has been taught in terms of social progress and evolutionary development – to say nothing of what the recently deceased astronomy popularizer Jack Horkheimer said at the end of every episode of his PBS program Star Gazer, which was to “Keep Looking Up!”

More Than One Side to the Alien Encounter Debate

Aside from the more than likely possibility that Skyline will be little different or better than the majority of alien invasion stories of the last one hundred years, using the real words of a real scientist (and a cosmologist at that) to give a sense of weight and urgency to just one side of the concept of alien interaction with our species and our world ultimately blurs and overshadows the wider range of possible behaviors and outcomes for what may one day define the ultimate course of humanity among the stars.

While it is true that the primary overall purpose of Skyline is a material one – to line the pockets of its makers with money by appealing to the basic instincts of those who will provide said profits – the film (and Hawking) are nevertheless contributing to the debate on whether and how we should deal with other intelligences in the Cosmos. This is the case whether the filmmakers had any deep intentions of doing so or whether the idea is plausible or not.

Since so many science fiction stories about aliens tend to focus on the negative aspects of and possibilities for encounters between varied species, thus biasing (and reflecting) public thought on this topic, it is both fitting and important to take a look at just how plausible Hawking’s dire prediction and all the related ones truly are. There are of course certain limits as to how much one can reasonably determine what an ETI may or may not do in regards to humanity in its present state: Not yet knowing for certain scientifically if there is any life beyond Earth tops the list here. However, we do possess enough scientific and technological knowledge to make some plausible determinations on just how likely our greatest fears about our galactic neighbors might be true or not.

Image: Skyline‘s imagery portrays alien encounter as disaster. Credit: Universal Pictures.

Just as there has to be a set of solid parameters for current SETI on this planet to work, meaning that a society has to have both the means and a purpose which presumably is not willingly detrimental to itself to signal others across space and time, so too must there be some sense of foundation regarding an alien invasion or attack.

As SETI requires its hypothetical subjects to share some common elements with humanity in order to work, any beings who wish to do harm on us must also think and behave with some similarity to us. So when examining the types of invading alien beings, I am excluding the ones with abilities we would consider to be godlike: Able to appear at will anywhere or anytime and commanding so much knowledge and power as to make the act of rendering us extinct a quick and easy exercise. I make the presumption that if such superbeings wanted us gone, it would have been done by now. The fact that it has not happened could mean a number of things, such as they are much too smart and nice to harm lesser life forms, or they don’t care about us one way or the other, or they will destroy us but they just haven’t gotten around to it yet. As a result, I am staying away from speculating any more on the superETI, except to warn that beings which are given abilities to do just about anything blur the line between physics and supernatural magic. In addition, I make no pretense that my lists of alien motives and weaponry are in any way complete, so further ideas are welcome.

The Why of Alien Invaders

Assuming that invading another world across interstellar distances requires some serious time, currency, and resources, our hypothetical alien marauders will not be attempting to take down humanity and its home planet on a whim or to follow some cliché of galactic hegemony. Like the future humans in the 2009 film Avatar who travelled 42 trillion kilometers to reach the Alpha Centauri system moon Pandora for its mineral wealth to aid their ailing civilization, our invaders will have to come up with a very good reason for traveling all that way if they ever literally want to leave the ground.

Of all the “whys” for an alien assault on Earth, taking our planet as a new place to live and utilize because their homeworld is dying or destroyed for one reason or another, is at least as old as H. G. Wells’ The War of the Worlds.

Well’s 1898 novel was a combined reflection on how European colonizers of the era were treating the people and places they were colonizing and an extrapolation of the idea of advanced beings responding to the slow but inevitable demise of the habitability of their home planet, in this case the fourth world from Sol, Mars. The numerous astronomical reports of seemingly straight lines on the Red Planet since 1877 had led to speculation that they were artificial in nature.

One fellow, the wealthy American astronomer Percival Lowell, championed the idea that the lines were actually immense canals built by the Martians to bring water from the icy white polar caps to quench their drying and dying cities. While Lowell seems to have assumed the superior Martians would eventually accept the end of their species and become extinct with dignity, Wells imagined these same creatures not wanting to go down with their planetary ship, thus their invasion of Earth.

Image: This early issue of Hugo Gernsback’s Amazing Stories brought H.G. Wells’ War of the Worlds to a new audience.

Now of course one advantage Wells’ Martians had over just about any other species in the Milky Way galaxy was living so relatively near to our world. A conventional rocket can propel a spacecraft to Mars in a matter of months, as they have in reality since the early 1960s. However, it is an entirely different matter to send a ship between even the nearest stars. Unlike the vessels of science fiction which are equipped with fanciful warp and hyper drives or have a conveniently placed cosmic wormhole nearby, our current knowledge of what it would take to get from one star system to another is fraught with technological and celestial hurdles that make even a slow multigenerational ship a daunting task.

So even if say an alien planet was going ecologically, geologically, or cosmically south, would it be wise to say nothing of practical to send a fleet across interstellar space to take over another star system, when unless their sun was turning into a red giant or going supernova, it would be much easier to utilize the worlds in their own solar system for resources and settling. If, for example, an alien society was in desperate need of water like the Martians of Lowell (and presumably Wells), it would be much cheaper by comparison to mine the many, many comets that we know exist around other stars, just as they do at the fringes of our Sol system. And while we have yet to detect any exomoons, we do know that most of the moons circling the four Jovian planets are covered in water ice and in some case, like Jupiter’s Europa, likely have deep global oceans of liquid H2O.

The same goes for mineral resources. There are estimated to be many billions of whole solar systems in the Milky Way galaxy alone. Presumably they have lots of planetoids in addition to their major worlds and the comets, just like our celestial neighborhood. It is also probable that many of those worlds are uninhabited but rich in elements that a technological civilization would find useful. So even if our marauding aliens do want to journey all the way across the galaxy for gold or oil or whatever, with so many star systems to choose from, why focus on Earth and its environs when the pickings are so easy and plentiful elsewhere? Plus since hauling all those rocks home would be expensive as all get out, trying to colonize a solar system that already has one intelligent species, even if that species is just starting to explore and utilize space, might be more trouble than it is worth.

Now let’s look at another classic reason for an ETI to want to come to Earth: Dinner. It has become practically an old joke that some aliens would see all the teeming life forms covering our planet and consider us an open buffet. Not only do we once again invoke the question of whether it would be worth going to all that time and expense for a meal when there are probably much closer snacks at home, but it has been said that our biochemistries would be so different that Earth organisms would be pure poison to an alien creature (and vice versa). The vastly different genetics would also go for interspecies breeding, especially since it is considered unlikely that we and they will look anything alike. As for needing a race of slaves – robots would be so very much less expensive and far more efficient. This all sounds like some very old and very low-grade science fiction in any event.

Image: This classic episode of Twilight Zone featured Damon Knight’s short story ‘To Serve Man,’ in which the idea of humans as menu items made a sardonic appearance. Credit: Cayuga Productions/CBS.

If it is just too much to fly all the way here for rocks or a meal, are there any other reasons why an ETI might still want to exterminate us? We may not be a threat *now*, but perhaps some day if we do spread ourselves into the galaxy, there might be others who could see us as future cosmic competitors for all the places and resources previously mentioned. If the galaxy has beings who think and act in very long terms, certainly much longer than most present humans do, they may not want to wait until our descendants are arriving at their doorsteps and instead take us out now.

I for one would like to think and hope that a stellar island of 400 billion suns over 100,000 light years across with perhaps 100 billion galaxies beyond our Milky Way in a Universe 13.7 billion light years wide would be plenty for everyone. However, perhaps some cosmic real estate is more choice than others and its finite nature makes it a valuable target worth fighting for. One estimate I saw in a Scientific American article from 2000 said the galaxy could be conceivably colonized in just 3 million years – a very short time compared to the 10 billion year age of the Milky Way. The fact that our planet appears to be free of any alien conquerors/settlers may say something about that idea, or perhaps conquest and colonization is not as popular as we might imagine (and often do).

Even if we and others decide to be planetary homebodies for many generations, there will come a day when a home system’s main source of light and heat, their sun, will begin to die out. Our yellow dwarf star is no exception: Sol is expected to start making things pretty unbearable on Earth in just a few billion years as our sun begins to expand into a red giant star. Even if Earth is spared being swallowed up by this bloated monstrosity of hot gasses, our planet will be cooked into molten slag, killing anything living that remains. Earth will later turn into a frozen iceball as Sol shrinks into a white dwarf and eventually a dead, dark cinder of itself. Even if our planet survives all this in at least its physical presence, when Sol goes completely so will Earth, its icy battered carcass floating off into the depths of the Milky Way as a rogue world.

So while we do have several billion years to prepare for this event, the point is that eventually nature will force our hand and make us choose either flight or extinction. Even staying in distant parts of our system will pass once Sol starts collapsing upon itself. And this is the fate of every star some day, even the very long lived red dwarfs, though some suns will also turn supernova or collapse into neutron stars or black holes. I know things will be very different in those distant epochs, but doing more than briefly visiting Earth or anyplace else nearby in those eras seems infeasible at best and deadly at their worst.

Have other species around other suns realized this about their celestial hearths as well? Will they decide to stay at home and wait for the end, or will they pack up and look for worlds where their suns won’t be going out quite so soon? Will the fact that we have at least a few billion more years of relative safety be appealing to such refugees? What happens when it is our species turn some day? Perhaps there are many vague and hidden factors which will render all this particular speculation and prediction moot, but at least this idea has the merit of being a plausible reason why one might have to go interstellar voyaging.

Image: From the film Alien Invasion, strange craft fill the skies over Earth’s cities. Credit: Richmanclub Studios.

Another reason ETI might want to come to Earth is a religious one. Perhaps like certain segments of humanity there are alien beings who have very strong spiritual and religious beliefs and it is their sacred duty to share the Good News with everyone else, whether they want it or not. Will alien missionaries ply the stars seeking to convert other species to what they perceive as The Truth, perhaps affecting their “heathens” in the same way that missionaries affected the cultures of the Pacific in their zeal to save souls – settling in some very nice real estate in the process. What will happen when a human group and an alien collective of very intense and very certain religious missionaries encounter each other? Or is religion a primarily human concept? Well, so far we have not been forced to worship any strange alien deities by clergy from the stars. Unless some of our current religions were the direct result of an ancient missionary visit.

How Might They Vanquish Us?

Although we have now looked at the primary and most obvious motives (to us at least) for an alien species to want to crush humanity and found most of the feared concepts wanting, it is time to explore the ways that said alien marauders might still take us out of the galactic picture. Ironically, while the potential motives for invasion and destruction are often weak if not outright impractical or implausible, the methods that a smart but aggressive species might want us gone (or we they) are often even more likely and effective than the usual imagined scenarios for the conquest of Earth.

If asked to visualize how an alien race might come after humanity, the scenario that seems to jump to most people’s minds is the one of giant spaceships hovering over major cities (Skyline is just the latest incarnation of that scenario), or a whole fleet of shiny silver spinning disks carrying troops of alien soldiers wearing shiny silver spacesuits and gripping laser rifles in their clawlike hands.

Now while one cannot entirely rule out the possibility that one day Earth’s skies will be filled with large and dangerous alien vessels up to no good for us, the idea that more advanced beings would engage in a battle for Earth and against humanity in a manner similar to the scenarios described above seems about as efficient as targeting our world for its supply of water with all the much easier and more effective alternatives available.

If you want to get rid of the higher life forms on Earth and don’t care if most of the flora and fauna inhabiting our globe also gets destroyed in the process just so long as the planet remains intact, then all you need to do is attach some rocket motors to a collection of planetoids and manipulate them so their ultimate destination is Earth. Humanity could be doing this with some of the smaller varieties of space rocks in just a few decades if we choose to, so a species that has actually made it to our Sol system via starship would be able to conduct this activity too.

Depending on the size and mass of the planetoid and where the ETI would target it, our civilization if not our very species could be rendered helpless in short order in a style reminiscent of the dinosaurs 65 million years ago. Indeed, there have been a number of small planetoids which have come close to Earth in recent times that astronomers discovered just a few days before their close encounters, leaving very little to no time at all to develop any countermeasures had they been on an intercept course. And these objects were guided only by the forces of nature! A deliberate use of planetoids to smash us into submission or worse is a scenario that has been discussed and written about, but a real organized defense system is still decades away.

An even more frightening concept is using a starship itself as a weapon. A large enough vehicle moving at relativistic speeds, even a fraction of light speed, could hit Earth with more force than humanity’s entire nuclear arsenal at its peak in 1990 (55,000 nuclear bombs). Such a weapon would be very hard to track and virtually impossible to stop at our present state of things.

Image: Artist’s impression of an asteroid strike. Do we have any defense against this kind of impact? Credit: NASA.

The details on this scenario, along with a very interesting discussion as to why an ETI might do such a thing to us and others (take out any potential aggressors/competition before it does the same thing, in essence) may be found on this part of the Aliens chapter of Atomic Rockets from Winchell Chung’s fascinating Web site.

Keep in mind that while Chung does make some very compelling arguments, he is also a very big space war gamer, so having a galaxy full of mature, peaceful, and altruistic beings may make for a nice place to live on a cosmic scale, but a rather dull RPG. Going on the offensive with other species is also a pretty good guarantee that even an advanced ETI that gave up aggression and war ages ago may not like being threatened or seeing others in such a state and take action against such a paranoid and self-serving race.

Another method for taking us out is one that has probably happened naturally across the Universe since the first stars came along: Supernovae. An exploding star would not only vaporize the members of its system but spread deadly radiation for hundreds of light years around. Earth has obviously survived having its native life forms become completely extinct by any stellar explosions over the last four billion years (and we can thank a supernova for even being here in the first place, as astronomers say it was the violent death of an ancient star some five billion years ago that kick-started the cloud of dust and gas that became our Sol system, along with giving us the elements needed to make life possible), but if an advanced species knew how to make and control a stellar detonation, they could fry us and our galactic neighborhood. Other methods of sterilizing whole solar systems includes smacking two black holes together and directing galactic jets, which are streams of particles and radiation thrown out by massive black holes in the cores of some galaxies. One hopes it won’t be possible to harness such energies, but who knows what beings that can survive and grow for eons in this Universe might be capable of.

Another cosmic weapon which fascinates and frightens is known as the Nicoll-Dyson Beam. Dyson Shells are a fascinating concept in their own right: Freeman Dyson envisioned a society taking apart its solar system and building a vast swarm of communities around its sun to collect as much energy from it as possible (right now 99% of Sol’s energy gets “wasted” into space). From a distant vantage point, anyone monitoring such a system would see its star gradually dim in the optical realm and brighten in the infrared region of the electromagnetic spectrum.

Being able to collect and utilize so much energy from a sun has many benefits for an advanced technological society – and a few dangers for others as James Nicoll would later point out. Dyson Shells would be able to focus and redirect the solar energy they collect into tight and powerful beams called a phased array laser. The beams could easily destroy whole worlds many light years from the Dyson Shell.

Whether Dyson Shells actually exist and would their makers use them as galactic-scale weapons is another matter (though there have been actual SETI programs which attempted to find these astroengineering projects), but this page from the Orion’s Arm Web site gives an interesting visual and text description of this idea.

Is SETI Itself Dangerous?

There have been many who warn about sending greetings and other messages into the galaxy and beyond. The idea, called METI for Messaging Extraterrestrial Intelligences, is that since it may be hard for an alien species to find Earth and humanity among the 400 billion star systems of the Milky Way, we should increase the chances for detection by broadcasting into deep space towards what we think are favorable cosmic places for intelligent life. The main idea behind SETI is that alien beings are conducting their own METI programs, as that is likely the best and easiest way for humanity to detect another society in the galaxy at present.

The main and obvious issue with METI is that we do not know what other kinds of beings are out there. Folks such as Carl Sagan have speculated that aggressive species tend to wipe themselves out before they can achieve space travel. However, this has the flavor of painting an alien race with the traits and behaviors of our species. What if there were species which cooperated as a unit and still decided that other beings must go before they become a threat to them? Or what if they felt that other species, being viewed as inferior, were in need of a serious “makeover” that would effectively destroy whatever made the target species unique?

Some have speculated that an ETI might take out humanity and any other species at our stage of knowledge and development by operating a METI program that carried what we might call an artificial virus. The target species would pick up the alien “message” and in the process of decoding it would unleash a program that could do all sorts of dangerous and deadly things, from taking down our technology to giving us the plans for a superbomb that would detonate once we built it from the instructions given in the message. Other potential scenarios involve converting humans into their puppet slaves or replicating the alien species on Earth to take over and then aim more such messages at other potential worlds to continue their galactic conquest.

Of course it would seem easy to make sure that this never happens by simply keeping the alien message isolated or just never building the design plans. However, the combined excitement of detecting an ETI signal and the often wild, vast, and intricate nature of the Internet could bring about the spreading of the virulent message and be released by those who feel it is their right to have and know such information. In addition, as we see in the news on a regular basis, there are those groups of humans who might deliberately want to open up this cosmic Pandora’s Box to spread death and destruction across our planet for their own purposes.

Image: As iconic as it gets, this still from Independence Day highlights the menace from above. Credit: Twentieth Century Fox Film Corporation.

This Web site goes into detail about the possibilities for an alien species to take out Earth without ever having to leave home either in person or even through a robot vessel.

Final Thoughts

This essay began thanks to Stephen Hawking’s well-publicized views on alien intelligences which he thought would not be a good thing for us to encounter any time soon. While there is of course the possibility that we might encounter an alien species that is a threat, I was unsatisfied and disappointed with Hawking’s version of this scenario. It struck me as not only being one-sided, limited, and old fashioned in thinking, but far too reminiscent of numerous recent Hollywood-style science fiction plots – an industry not exactly known for its rigorous scientific accuracy.

Hawking’s take on alien life feeds into this negative, paranoid, and inward-looking attitude regarding the unknown that seems to be growing in human society these days. While it is prudent that we do not just jump into the galaxy without at least having some idea who and what is out there, focusing on the idea that all alien beings are hostile monsters and that we should dismantle our radio telescopes and hide under our beds is not exactly the actions of a healthy, maturing society. Besides, if an ETI were out to get us, remaining ignorant of the Universe and trying to be undetectable is not the way to go.

As I have pointed out in this essay, an advanced alien species will be able to destroy us in short order and we will have little recourse to stop them at present. The fact that it has not happened may mean they simply haven’t found us yet, but it may also mean that we are either lacking in large numbers of intelligent galactic neighbors or that taking out another species that has barely gotten its feet wet in the cosmic ocean is not the way to behave as a galactic society. We still have far more to worry about from members of our own species bringing down civilization than any hypothetical alien species anyway.

Another thing I do know about human nature: No matter how many warnings and precautions and even laws that get thrown up to control people when it comes to what society thinks is in its best interests, there will always be individuals and groups of people who defy these rules either because they disagree with them or because it is in their nature to go against the grain.

This will apply to voyaging into space as much as anything else. The only reason it hasn’t happened already is due to the technological difficulties in making a deep space mission a reality at present. However, I know once we establish a serious foothold in space in our Sol system, there will be groups who will not want to remain confined to our celestial neighborhood but want to venture to those countless stars surrounding us. This will keep happening for as long as humanity lasts.

This is the eventuality we must prepare for, because I will agree with Hawking on one thing: If life’s evolution is similar everywhere, then it is likely that some other species will also share our drive and desire to see what it out there beyond their home world. It may be only a matter of time before we are visited. How we respond to them depends not only on their intentions but how much we have learned and evolved when it comes to understanding the Universe as well. Hopefully we will not let our fears and hostility turn a potential friend into an enemy.