Would E.Ts try to kill us off? (Nope. They’d be deterred.)

There has been some debate in the sciencey & science fictionish circles about whether searching for and contacting extra-terrestrial aliens is really such a great idea. No less a luminary than Stephen Hawking recently warned the humanity about the possible dangers of phoning the E.T. (as if the humans would listen…), and contact with hostile aliens has understandably been a staple of science fiction since the beginning.

In fiction, aliens are usually depicted lusting after our planet/water/bodies/female bodies (cross off as appropriate).  There are some reasons to believe that these fears may have been exaggerated: as long as there are much easier pickings remaining in, say, the Asteroid Belt or the Oort cloud, a species capable of traveling across interstellar distances does not seem to be very likely to need much anything from the bottom of a deep gravity well also known as the Earth. Curiosity items and biological/historical information, perhaps, but wars do not seem to be the optimum method for obtaining them. Trading would be much easier for all concerned – and let’s face it, put a bit of glassbeadanium from a hyper-advanced civilization on offer, and you’ll get all the museums and collectors on Earth lining up for a chance to trade whatever treasures and/or employees they have for it.

However, some more recent works, such as The Killing Star by Pellegrino and Zebrowski (1995), depict a bit more dystopic universe. These authors have thoroughly understood what is also known as the Jon’s Law: Any interesting space drive (i.e. anything that is capable of interstellar flights in at least somewhat reasonable timescales) also happens to be an immensely powerful weapon of mass destruction.

Why? Because interstellar travel requires pretty humongous expenditures of energy. And that energy needs to be controlled very carefully; as one thinker puts it, how would you like to have the captain of the Exxon Valdez skippering a tramp freighter with an antimatter drive?

Consider just a rather simple, down-to-Earth example, a beamed propulsion space probe proposed by a noted hard sci-fi author and rocket scientist (no, really!) Robert L. Forward (1984, 1996). He believes that using only technologies currently being developed, and a rather modest outlay of funds compared to, say, the Olympics, the humanity could soon send a 785-ton interstellar probe hurtling through the cosmos at a rather brisk pace of 50 % of light speed, or 0.5 c. Now, what happens if this small probe just happens to have a slight brush-up with a planet?

It goes boom. Big time; with some 2600 gigatons to be precise. To get a sense of scale, one estimate puts the entire nuclear arsenal of the entire Earth at somewhat firecracker-y 6.4 gigatons, give or take some decimals.

I don’t know for sure what 2600 gigatons of flaming relativistic death will do to a planet, but I’m fairly certain it’d be bad news all round. There is a reason why techno-jargon for these things is Relativistic Kill Vehicle, or RKV. (Yay, acronyms!)

And did I mention that stopping a chunk of metal that’s coming for you at 0.5 c seems to be somewhat “challenging,” no matter what kind of technology you would be using? Even if the probe can be hit, much of it would simply break up – and instead of a single planet-shattering blast, you’d get what would amount to nearly 500 all-out nuclear wars being fought within a second. Not exactly good news, that. In fact, if one wants to relativisticly fry an inhabited planet, the optimal approach would most likely be to break the RKV into smaller fragments well before impact. Harder to detect, harder to intercept, more chances of hitting the planet and something important in it, and less energy wasted into gigantic fireballs that promptly exit the atmosphere. Also, longer baseline for distributed sensors, meaning better targeting capability.

That, my friends, was a single small probe from a pretty sub-standard civilization that has barely learned how to fly up to space and not burn all up when coming down. What if the attacker is using three such probes? Or twenty? Or rather larger 7850-ton ships Forward believes we could also have relatively quickly? (26 000 gigatons per ship, enough to punch sizable holes in the planet’s crust.)

In short, it seems that Attack will always be more effective than any Defense. The Attack Will Always Get Through, and when it does, the results will be spectacular. (From a safe vantage point that is, i.e. from the next star system.)

So – either interstellar travel is not really feasible, in which case we have little to fear from the E.Ts and the discussion whether SETI is a Good Idea is largely moot, or it is feasible, and we have the aforementioned problem. In answer to which, any aliens could be hell-bent on killing us off sooner rather than later simply because

  1. Their survival will be more important than our survival; if an alien species has to choose between them and us, they won’t choose us.
  2. Wimps don’t become top dogs; no species makes it to the top by being passive.
  3. They will assume that the first two laws apply to us. (Pellegrino & Zebrowski 1995, p. 115)

In other words, we could be under threat simply because we may be a threat one day, some day. This is a sobering thought: if it is possible that we may be a threat, shouldn’t it be rational to exterminate us sooner rather than later?

Fortunately for us, there is one thing working in our favor. The alien attackers do not know whether we can already retaliate. Yes, they might fry us with their RKV’s or Alien Death Zappers (ADZ’s for MOAR acronyms!), but are they sure we are not hiding any of our own in the Asteroid Belt, for example? Really sure?

Of course, we know we don’t have those things. But think about an alien civilization picking up the first TV broadcasts from the Earth – incidentally, they’d probably see Hitler opening the 1936 Olympics, which may not be the best introduction to our species unless they’re really into uniforms, but let’s leave that for now. Could they really piece together enough information from our 1950s soap operas, observations of Earth from a distance, et cetera, to absolutely rule out that this species is incapable of building RKVs or something even nastier? What if – let’s say – the grainy broadcasts are all part of some futuristic version of a Renaissance Fair, or a religious ritual? What if it’s a trap ?

And if they then send their killer probes, what will happen during the 200-2000+ years or so the probes will need to reach us? (It seems likely there are no advanced civilizations within 100 light years from Earth, although one must always be ready to be surprised.) Are they really, really sure we then don’t have technologies, if not to defeat the attack, at least to respond in kind? After all, the aforementioned planet killers are likely to be within our reach during this century, and any space habitats in out-of-way places like the Asteroid Belt would have a good chance of surviving the initial attack.

Furthermore, are they absolutely certain we’re not talking to any other aliens? It would be somewhat suspicious if the last message from the Earth would scream about relativistic attack, and the recipients would very likely want to lock’n’load some RKV’s or ADZ’s of their own. Yes, nth aliens are unlikely, but if you find one species, that’s existence proof that it’s not impossible.

In short, it would seem that any civilization that has any reason to be afraid us would also be so afraid of us that it’s far from certain they would really want to hit us first. In other words, they would be deterred from attacking. Yes, they might be very concerned if humans get their dirty hands on relativistic space probes, and they might take a dim view of us practicing parallel parking with those vehicles in their neighborhood. But concerned enough to launch a preventive attack? Hardly.

After all, we’ve been there and we’re still around to tell the tale. From the late 1940s, a group of very eminent minds – including John von Neumann, widely considered one of the greatest mathematicians ever – became increasingly concerned with what they saw as the relentless logic of nuclear war. If there is a non-zero probability of a nuclear war, they said, it is logically only a matter of time before a war breaks out. And given the trend towards increasing numbers of nuclear weapons, a war in the far future would be far more devastating than a war today. So, they and their followers in the military argued, let’s bomb the nasty Commies before they do the same unto us. An example is given in the 1954 briefing to the President Eisenhower by a U.S. Joint Chiefs of Staff advance study group: the U.S., they said, should

“…deliberately precipitat[e] war with the USSR in the near future… before the USSR could achieve a large enough thermonuclear capability to be a real menace to [the] Continental U.S.”

(Kaku & Axelrod 1987:101)

Another air staff study from the period concluded that anyone calling for restraint and relying on retaliation in the event of nuclear attack, i.e. not advocating surprise attack, was a

“…pseudo-moralist who insists that [the U.S.] must accept this catastrophe.”

(Kaku & Axelrod, 1987:100; Rosenberg, 1983:196)

Substitute Aliens for the U.S., Humans for the USSR and RKV for thermonuclear, and there you go. Von Neumann et al‘s logic was sound, in theory, but in practice, these things are fortunately not so simple. It’s quite widely acknowledged now that the logic of deterrence – the inevitable retaliation – made deliberate nuclear wars pretty much impossible, although accidental wars remain threats enough on their own (as I’ve written before). I see no real reason why deterrence wouldn’t work in interstellar relationships: if hitting us is seen as a strategy to ensure continued survival of the alien species, and if any humans survive for long enough to hit back – even if retaliation takes hundreds of years to find and reach the perpetrators – the strategy will be deeply flawed. Simply put, the negative payoff from a not-100%-successful attack will be so large, and the likelihood of the attack being 100% successful so low, that ensuring survival of the species is not a good reason to try to kill off another. (Yes, there may be other reasons, but these, too, will be at least somewhat deterrable.)

But that’s enough qualitative rationalization for now. The next installment of this post will detail the history of One Million Interstellar Wars, fought by yours truly (it’s amazing what you can do with telepresence these days). With that, I’ll show quantitatively why preventive attacks are generally not a good idea – except, perhaps, in a few well-defined cases. Also: what we can do to avoid painting a bullseye on the Earth.


About J. M. Korhonen

as himself
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10 Responses to Would E.Ts try to kill us off? (Nope. They’d be deterred.)

  1. Nice stuff! But what if the E.T.’s have abandoned their home system and travel around as a swarm of spaceships, just stopping to refuel / resupply if necessary?

    • The energy resources required for large-scale interstellar travel are so large that it is hard for me to believe anyone controlling them would need much anything from other civilizations at this stage of our galaxy’s history (i.e. it’s not yet mined empty). Certainly not basic materials!

      Anything so sophisticated aliens would need, they’d get easier from resources that are outside gravity wells, like the Oort cloud or the Asteroid Belt. What they cannot find there, they can synthesize given that much energy. If they are capable of relativistic (i.e. slow) travel between stars, they’re very well adjusted to living in space, probably to the extent that they’re not willing or perhaps even capable of living on planets any longer. So even if the Earth’s environment would be suitable for them, it’s uncertain whether they’d want it even if offered. And living in maneuverable spaceships, they’d have little to fear from our experiments with relativistic rockets etc.

      Of course, killing for fun or for some alien (perhaps religious?) reasons cannot be fully discounted for, but deterrence works – at least to an extent – even against very advanced crazies.

  2. Hagbard says:

    Doesn’t this rather assume that any E.T. happening across the Solar system is a (relatively) lone representative of a cohesive culture? What if they’re part of an expansion wave, driven forward by depletion of resources elsewhere?

    If there’s life out there, probably there is, or has been, more than one species. The most likely to spread would be one with an aggressive tendency to grow. Such a species, if capable of interstellar travel, would devour all resources available to them, at an alarming rate. They would travel from system to system, set up for resource exploitation, populate all suitable areas and quickly end up at war for resources, either internally or with other species. The resource pressures would become unbearable and some offshoots of this species would move on to repeat the same process elsewhere. Given the timescales involved, speciation would also occur.

    Should we encounter such an incursion into the Solar system, the intruders might not care much about the risks of going to war with Humans. They’d be between a rock and a hard place anyway.

    What I’m getting at is that in this scenario, there would not be “them”, or in the more distant future, even “us”. There would be various mutually hostile factions competing for resources, and after any conflict the victor faction would experience a short outburst of growth followed by a splintering into new, mutually hostile factions competing for resources.

    • Thanks for the comment, you are right on the money! The full version of the paper I’m preparing based on this will consider this dynamic and is more general than this paper, as I talk about civilizations, not species. The scenario outlined above is mostly concerned with intentional surprise attacks by Extra-Terrestrial Intelligences (ETIs) that learn of us and fear we could be a threat to their existence. The dynamic itself doesn’t change if you increase the number of factions. The main difference is that there are more uncertainties to account for (which typically does not favor the attacker).

      Expansive civilizations are not necessarily threats to us, because we can’t currently threaten them, and they can get what they want from outside the Earth anyway. As I stated above, a civilization that has mastered interstellar travel has little to gain in the inner reaches of star systems; they can get whatever they want much more easily from the asteroid belt, the Oort cloud, the gas giants etc. for a very long time before they have to bother with gravity wells of rocky inner planets.

      They also don’t have to take risks with inhabited systems in the Milky Way for a long while, as there are likely to be a huge number of uninhabited, unvisited systems left. (If exponentially hyper-expansive civilizations existed, we should be seeing signs of them now, even seeing them within the Solar System.) A civilization strip-mining the Oort cloud might of course swat us down if we are a nuisance, but it’s hard to believe they’d have any reason to destroy us outright. Therefore I don’t see them as threats to us in a way Hawking or Pellegrino for example see them.

      I don’t believe any species capable of long-distance space travel will be growing at exponential rates (which is pretty much necessary for total resource depletion). The requirements of interstellar travel necessitate harnessing immense energy sources and finding practical ways of living almost indefinitely within closed-loop systems, and once such systems are invented and in wide use, why take the risk of retaliation by attacking someone for relatively easily obtainable resources? Being adapted to living in space, even planetary surfaces (especially on planets with corrosive, unstable atmospheres as the Earth) are likely to be more of a bother for them than anything worth going to war for.

      Furthermore, aggressive civilizations are a threat to all other civilizations, including those of their own species (and even more to those, considering that members or close cousins of the species are the nearest competitors for any resource). It should follow that aggressive civilizations run a high risk of being R-bombed out of existence.

  3. Nikki Lee says:

    Interesting article! Well I’d probably be crossing out the possibility of extraterrestrials coming to our little blue planet looking for water since there’s this massive reservoir in space for this precious resource (http://www.zmescience.com/space/enormous-water-reservoir-found-in-space-is-bigger-than-140-trillion-earth-oceans/). 🙂

    Thought of sharing some viewpoints on these ‘new-age’ stuff I’ve been reading (it might be a little off the topic but I’ll share nevertheless). According to one of these authors (I forgot which book, please do pardon me!) earth is like an experimental ‘project’ to see how different species cope, survive and grow together. And it seems that this experiment has been hugely successful, to the extent that other potential galactical races are considering claiming this planet as one among their clusters. Farfetched idea, and somewhat whimsical, but I do not discount the possibility of it at the same time.

    Yet others say that we are descendents of the Pleiadians (and several other races to which I just could not remember) based on analysis and studies of marks on those ancient monuments/artifacts. But most agree on one thing. We have more than 90% of so-called ‘junk DNA’ within us that are non-activated or involved in our bodily processes. So it is possible that once activated, we as humans actually harness far more capabilities than we could imagine. A theory of the ‘homo sapiens’ being elevated to ‘homo luminous’. Maybe the ETs are here to witness how we have evolved over time (unless of course, they come with probes and experimental equipments) 🙂

    I apologise for the long comment! I could go on and on but I figured I’d better stop before I go into more of inter-galactic discussions and quantum physics theories. :))

    • Yeah, water is hydrogen + oxygen, the former is the most common thing in the universe and the latter isn’t exactly scarce either :).

      There is so much stuff basically floating out there that it’s hard to see any ETs who are capable of building actual starships even wanting to come down to Earth and expend all that energy fighting against gravity when going up again. It’d be like having to go to Alaska every time you wanted to go shopping…

      What you say is known in the SETI discussion as the “zoo” or “quarantine” hypothesis. Could be true, though there’s at least one paper that argues the quarantine is unlikely to hold. And the problem with these hypotheses is always the same, proving the negative. But that’s a problem with most of the SETI stuff anyway, so I don’t really care :).

      There are probably simpler explanations for the junk DNA, but if there’s something biology has taught me, it’s that the universe is not just weirder than we think but weirder than we can think!

      BTW, I’ve been reading some summaries of SETI – as not even nearly all the interesting wavelengths are even monitored, the only thing we’ve been able to prove so far is that there are no deliberate, immensely powerful radio beacons out there, at least not within the closest 1000 light years or so. For what we know, there could be hundreds of civilized worlds chatting away with each other via directed high frequency beams, perhaps lasers or masers, and we’d have no idea because intercepting those transmissions is almost impossible.

      Although there are about a dozen very intriguing transient signals that COULD have been signal beams accidentally sweeping the Solar System – but they don’t really count because no one has been able to reacquire them. Which is exactly what one would expect if they were directed transmissions only accidentally sweeping the Solar System.


      • Nikki Lee says:

        Thanks for the link! Interesting read about the signal! 😀

        Your likening of the starships (and I just realised, you’re the first among my friends who uses the term ‘starship’ instead of ‘spaceship’! 😀 yay!) in descending upon Earth to going shopping in Alaska is funny haha.

        I didn’t know that SETI actually had that hypothesis. I’m sorry as I have not been following SETI much. I just thought that sometimes there might be things untold – no offence but I feel the same way about NASA 🙂 I fully agree with you on the high frequency wavelengths theory! It was running through my mind earlier about the possibility of other galactic members or even the starships vibrating at higher frequency levels of which we cannot perceive through our senses. Hence we come to the conclusion that there are no other life forms out there, no starships, and yes, no signals or wavelengths or messages at that. 🙂 I’m glad I’ve finally met a friend who shares the same views!

        Personally, I’ve always felt that there are other worlds around us. Its just that we at this 3rd-dimensional space can’t see or feel or hear them. Maybe these beings exist within 5th or 6th or even higher dimensions. And that brings us back again to the frequency levels. And topics of parallel universes and strings theory. And why elevating one’s vibrations to higher states through meditation/similar activities allows one to gain invaluable experiences.

        Back to the topic, I don’t see a reason why ETs would want to kill us, unless the intention is to hijack this planet or enslave populations or something along that. Sometimes we fear the unknown, and we turn defensive because of that, which consequently leads to bigger problems. But with an open heart and calm demeanor, things could altogether be different. 🙂

        p/s: may I suggest a book I’m currently reading? Was reading the Mandarin version but just had to order the original. Letters to Vanessa by Jeremy W. Hayward 🙂

      • The nomenclature re: spaceships and starships etc. could actually be a topic for another post :).

        A rule of thumb for ships and boats says ships carry boats but boats won’t carry ships. Or other boats. (That is, if we’re talking about motorized craft; if sailing vessels, it’s easy, as anything square-rigged with at least three masts is a ship and anything smaller is a boat, but I’ll return to that later.)

        So taking cues from this tradition, we could say that spaceships are vessels that

        1) navigate interplanetary space,
        2) and can carry smaller (crewed) vessels, like landers.

        Starships would then logically be vessels for traveling between stars (interstellar space) with smaller vessels tagging along for the ride.

        But! The technical term usually used for our current space going contraptions is “spacecraft,” not “spaceboat.” I therefore announce that this term denotes

        1) a vessel for navigating interplanetary space,
        2) that does not carry smaller crewed vessels.

        So we would have spaceships, spacecraft, starships, and (!) starcraft. The “crewed” distinction is there because otherwise space probes with landers in them would need to be called spaceships, and I just think that would be silly. (They’re pretty often called “spacecraft” in technical jargon.)

        The “smaller” part is also because of a definitional problem. Would the Apollo Command Service Module + Lunar Module combo have been a spaceship? I say no, because it was just two similarly sized spacecraft joined together.

        This becomes really interesting when you consider that the probe suggested by Forward in the above post would have used sails to ride the beam. Should that be then called a ship or a boat or a craft? What’s the equivalent of three masts and square rigging in space?


        Thanks for the book tip, will have to look into it! And for the comments as well :).

  4. Nikki Lee says:

    I’ll have to put a “like” to those definitions of starships, spacecrafts and the whole lot! Haha 🙂 Thanks for your time in explaining and defining them! 🙂 definitely made me think about those terms!

    Enjoyed the discussion! 🙂

  5. Pingback: MAD with Aliens? Interstellar deterrence and its implications | The unpublished notebooks of J. M. Korhonen

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