黑暗森林 – The Dark Forest

I’ve just heard an excellent podcast episode called ‘The 3 Body Problem Problem’, which you can listen to here. It’s very wide-ranging, and be warned, rather despair-inducing. I’m not going to go into too much depth about it, but I am going to talk about the Dark Forest Hypothesis in its social and political, and maybe psychological, setting, which is what that podcast already did.

The new Netflix series ‘The 3-Body Problem’ is an eight-part adaptation of 刘慈欣 (Liú Cíxīn)’s famous and award-winning novel, 三体, the first of a trilogy called ‘地球往事’, translated as ‘Remembrance of Earth’s Past’. In order to engage with this series in sufficient context, I feel like I’m going to have to zoom out so far that the actual trilogy itself is going to end up looking like an invisibly small dot on an invisibly small dot, and I don’t want that to happen so I’m going to have to break it down a bit. I am deliberately posting names and titles in 汉字 (Hanzi) because of the issues it raises. Two things about this: I am more used to Wade-Giles than pinyin romanisation and I prefer traditional Hanzi to simplified because the latter is trickier to associate with the ideas it represents. Looking at simplified Hanzi, which is what this is, is like having a migraine because there are bits missing from the characters which one really could do with being able to see. Yes this makes me a dinosaur, but non-avian dinosaurs would still be around today were it not for their “left hand down a bit” mishap 66 million years ago and there was basically nothing wrong with them.

I’ve read the first book of the trilogy. I didn’t so much not want to read the rest as find it an unnecessary financial outlay, so it ended there. Netflix too might end it there because they apparently haven’t had as much success out of this extremely expensive series as they’d hoped, so like several other series they may well cancel it way before time, while in the meantime adding lots of fluff to stories which were supposed to end like ’13 Reasons Why’, and while I’m at it, that book and series is interesting because it’s basically ‘An Inspector Calls’ for the twenty-first century and yet manages to be quite unfortunate in its implications regarding bereavement of people who have killed themselves (I don’t use the S-word because it’s not a crime). Anyway, before I get irredeemably off-topic I shall post a

Spoiler Warning!

and be done with it. So if you want to enjoy ‘The 3-Body Problem’, don’t read past here.

Before I get into the broader issues with the Netflix series and the book, I thought I’d explain what the Three Body Problem itself is. First of all, it’s fairly easy to work out where Cynthia (“the Moon”) and Earth are going to be at a given time, so for example we can easily work out when the phases happen, when it rises and sets, how far away they are from each other, when eclipses happen and how long lunar months are, and by extension the times of the tides. A lot of these things are also linked to Earth’s rotation, but the mathematics are fairly straightforward, although because both Earth and Cynthia move in ellipses relative to each other and the centre of mass (the “baycentre”) about which both orbit is not at Earth’s centre, and it would really help to know calculus, which I don’t, to make these calculations. Likewise with the Sun and Earth we know when the equinoctes and solstices are and how far away the barycentre of the two bodies is at any given moment to a high degree of accuracy. This is because Earth, Cynthia and the Sun and Earth are two bodies each when considered in that way. The fact that we can work out all this stuff in both cases also shows something else: that there are some straightforward pretty much accurate solutions for three bodies provided they’re in certain arrangements with each other. There are actually a lot of situations when the movement of three bodies fairly close to each other like the three mentioned here can be determined quite accurately. The case described here is simplified by the fact that Cynthia is both close to and much less massive than Earth and the Sun is much further away and more massive than either. Another very useful case is that of the Lagrange Points, where the balance between the gravity of two of the bodies is equal, leading to a stable point associated with them. Examples of this are sixty degrees behind or ahead of a planet or satellite in the same orbit, some cislunar point between a planet and its star or a planet and its satellite where the gravitational pulls are equal and cancel out, and some translunar point where the pull of Cynthia and Earth are again equal. As I’ve mentioned before on this blog, these points form a kind of “rapid transit system” around the Solar System which minimise the energy required to get between the various asteroids, moons and planets. There are other situations too. However, the Universe isn’t usually that neat and the majority of interactions between three bodies in fairly close proximity to each other are chaotic.

You really do need to look away now if you want to avoid spoilers.

The  三体 (Sān tǐ) are technologically competent aliens native to the Alpha Centauri system in the story. The Centauri system is in reality a ternary star system. Two Sun-like stars, one somewhat more massive and warmer than the other, orbit each other at a distance of between eleven and thirty-six times Earth’s distance from the Sun, whereas eleven thousand times the Earth-Sun distance, known as an AU (astronomical unit) from the barycentre orbits a much less massive red dwarf, Proxima, famously the closest star to the Sun except that since it takes half a million years to orbit the system so for some of the time it’s further from us than the other two, ignoring the fact that the entire system and the Solar System are both in their own orbits around the Galaxy. Right now, though, as its name suggests, its the closest. This situation, where two stars orbit each other much more closely than a third, is very common in the Universe and seems to be the most stable arrangement: the stars arrived in these positions after some chaotic behaviour and have now settled down. However, in 刘慈欣’s book, he imagines that a planet situated near these stars would have a chaotic orbit, some of the time getting too hot for complex life, sometimes getting too cold, sometimes being seriously perturbed by their gravity and sometimes almost being ripped apart by it and suffering severe volcanic eruptions. Life on such a planet could be imagined to be very difficult. It’s worth noting that this is not the real situation for most possible orbits of planets in the Centauri system, although it would be so for certain positions, such as for a planet halfway between the Sun-like pair or orbiting the Proxima far enough away to be strongly influenced by that pair’s gravity.

Due to the chaos of their home world, the 三体 decide to travel to Earth, and while doing so they also decide to harness the power of human intelligence by getting us to solve their world’s three-body problem through a VR video game where the player is put on the world in question, represented in a way humans can relate to, and has to find a solution to their predicament.

The first book, ‘三体’, begins in the 1960s during 毛泽东’s (Máo Zédōng’s) Cultural Revolution, where a scientist, 叶哲泰, is being denounced in a Struggle Session for his teaching of Einsteins Theories of Relativity. He is in fact killed in the process and his daughter, 叶文洁, is sentenced to hard labour followed by prison. This leads to her becoming very cynical about the human condition and our ability to improve things ourselves. Later on, she is employed as an indentured servant practicing science at a military base attempting to send and receive messages from any alien civilisations which might exist in other star systems, apparently focussing on the Centauri system. One day, she receives a message from an individual altruistic alien telling her that humans must at all costs cease to attempt broadcasting their existence and attempting to message aliens because it puts us all in danger. Because she now believes there is no way humans can sort out their own problems, 叶文洁 does the opposite, sending an enthusiastic message of welcome to the 三体, i.e. the aliens, and they proceed to plan to invade Earth, a process which will take four centuries because they can only travel at one percent of the speed of light.

There’s plenty more to both the series and the original trilogy, but this is enough to be going on with in terms of the details of the first book, and there is a particularly crucial point which is named after the middle novel of the trilogy: “黑暗森林”, or “The Dark Forest”. 刘慈欣 is not actually the first person to propose this idea.

Anyone who has read much of my blog will know that I think about the Fermi Paradox more than occasionally, but just in case you haven’t come across this, the Fermi Paradox, mentioned by the physicist Enrico Fermi in 1950 CE but not originally his idea, is this: the Universe is vast and there are innumerable Sun-like stars and planets orbiting them, and also æons old, so that life could have evolved from microbes to humans almost three times over or more given its age, and yet we hear nothing from intelligent aliens, are unaware even of the existence of life anywhere else in the Universe and have never been visited by them. In other words, “where is everybody?”. I’ve mentioned a few of the more interesting attempts at solving this problem in this blog. For instance, it might simply be that everyone else is really bad at maths and therefore there’s no rocket science on alien worlds, or it could be that the element phosphorus is always essential to life but is too scarce for it to happen very often, and when there are intelligent life forms, they can’t get out of their little oasis of phosphorus to reach other star systems, where in any case they’d have to take phosphorus with them to establish an outpost. One simple solution is that there’s no life anywhere else in the Universe at all. One I was keen on for a very long time was that other civilisations have something like the ‘Star Trek’ Prime Directive, that they can’t interfere with developing civilisations until they reach a certain stage of development. It could also be that there are plenty of civilisations which reach something like a twentieth century level of technological development but then end up wiping themselves out in a nuclear war, destroying themselves through climate change or developing artificial intelligence which then decides they’re a threat and kills them all. Note that I say “twentieth century level”: we could be living on borrowed time here.

Quite a lot of this is not at all reassuring. Perhaps even less reassuring is 黑暗森林, which is as I say not actually an original idea although it was 刘慈欣 who actually named it that. The exact metaphor was used by Greg Bear in the 1980s. The idea is this. There is silence out there because aliens elsewhere in the Universe are aware that broadcasting their presence would threaten their existence due to potentially hostile threats from other star systems, and humans are simply too naïve to realise what a bad idea it is to tell all and sundry we’re here. We don’t know any of them from Eve, and they could be really dangerous. They could just go, “ooh juicy, another race to enslave and another nice planet to conquer” and do something horrible to everyone. Another way of putting it: “it’s quiet. Too quiet.” It’s like the silence that falls over the clichéed hostile bar when someone from the Other Side enters.

Now I do not like this solution, to say the least. Obviously in saying that I could just be all weird about it and say, “well I don’t like this any more than you do, but facts is facts and it is what it is,” but that’s not what I’m saying. I might not like the course of a fatal disease or the policies of a particular political party, but it’s still possible to find that particular pathology interesting or the implementation of a particular set of policies fiendishly clever or elegant in a Machiavellian way. In this case, however, I see the solution itself as pathological, and apparently I’m not alone in that as you will find if you listen to that podcast. But I already had these misgivings before I heard it. The problem is that it’s very negative and cynical, which doesn’t necessarily make it unappealing, but more than that, it seems to be a reflection of the current state of the society, or perhaps world, in which it was written.

Because the thing is,  ‘地球往事’ is horribly, horribly grim and oppressive feeling. Suppose you look up at the skies and you see stars, an infinite horizon, endless hope and possibility and most of all for me the feeling that the atrocities and Hell we’ve made for ourselves on this small blue dot is as nothing compared to the hope the splendour of this unknown Universe around us shows. Even if it’s devoid of life entirely, it’s still magnificent and majestic, and moreover in spite of the actual Three Body Problem as opposed to the book, most of it works for pretty much of the time in one way or another. And if it isn’t devoid of life, there’s the optimism and awesomeness of a Cosmos replete with possibilities of friendship and fascinating variety. “Infinite variety in infinite combinations” as the Vulcans say.

There’s hardly any point in saying this, but just because something is appealing doesn’t make it plausible. I might be looking up at the sky with foolish, immature and groundless optimism. Absolutely, that could be so, and it’s very hard to decide whatbecause of the silence we all experience from the vast emptiness that surrounds us. So I don’t like it, but more importantly, what do the myths we make up say about us? What does it mean that 刘慈欣, in the 中华人民共和国 (People’s Republic of China) of the twenty-first century CE, is able to get this idea out to popular culture in the West via Netflix? Were there obstacles placed in front of him by the 中国共产党 (CCP) difficult to overcome, or were they not placed there in the first place because he perhaps has a knack of saying what they want him to say? Is he an establishment or an anti-establishment figure, and what does it mean that Netflix are apparently happy to stream what might be 中国共产党 propaganda? Or is it universal in some way, and if so is that universality a good thing or a bad thing?

‘ 三体’ has also been adapted by 腾讯 (Tencent) into a very different version. I know about 腾讯 on a personal level because someone close to me worked in 中国 (the Central State, i.e. China) for some time and the only way we could send messages to each other was through their app, QQ. Now I didn’t trust QQ very much at all and I was careful what I said on it, and I believe that was justified. One way of looking at this is that I’ve been duped by Western anti-Chinese propaganda, but it’s not that simple. QQ is their social media. Our social media are about as trustworthy, and this is not at all to say that 中国共产党 is better than the global megacorps. It’s more that they’re equally bad. It’s not about not trusting 中国. It’s about not trusting any big faceless organisation of any kind, because they simply will not have the interests of the ninety-nine percent at heart. We all know this.

Getting back to the actual Three Body Problem as understood in physics, it seems fairly clear that 刘慈欣 uses it as a metaphor for how unrestricted social systems are chaotic and unpredictable. A laissez-faire economic or social system, or a liberal or social democracy is just such a chaotic system, but it can be simplified by totalitarianism. If the likes of 中国共产党 and 腾讯, i.e. a few large organisations with a high degree of control over society, exist, we no longer have a chaotic Three-Body Problem but at least a special case of the problem like that of the Lagrangian Points or the Sun and Earth. Society can be made sense of and predicted. Likewise, in the West we have something like the social media firms, able to socially manipulate us all, and the US Republican Party, greatly simplifying the West through that extreme degree of control and gaslighting. So Netflix will be fine with streaming ‘The 3-Body Problem’ and by clamouring for a second season, which I must admit I personally want, we’re actually saying yes please, let’s have some more of that tasty propaganda.

There’s more than this though. ‘Star Trek’, and even more so Iain M Banks’s ‘Culture’ series and Ursula K Le Guin’s ‘The Dispossessed’, all provide a hopeful mythos for the nature of the wider Galaxy and optimism for the future. To quote from Banks’s ‘State Of The Art’:

Here we are with our fabulous GCU, our supreme machine; capable of outgenerating their entire civilization and taking in Proxima Centauri on a day trip…here we are with our ship and our modules and platforms, satellites and scooters and drones and bugs, sieving their planet for its most precious art, its most sensitive secrets, its finest thoughts and greatest achievements…and for all that, for all our power and our superiority in scale, science, technology, thought and behaviour, here was this poor sucker, besotted with them when they didn’t even know he existed, spellbound with them, adoring them; and powerless. An immoral victory for the barbarians.

Not that I was in a much better position myself. I may have wanted the exact opposite of Dervley Linter, but I very much doubted I was going to get my way, either. I didn’t want to leave, I didn’t want to keep them safe from us and let them devour themselves; I wanted maximum interference…I wanted to see the junta generals fill their pants when they realized that the future is––in Earth terms––bright, bright red.

Instead of such a myth, we are now asked to adopt 黑暗森林 as the explanation for the silence of the heavens, and maybe beyond that to accept that that silence justifies fear of the Other, and through that fear, as occurs later in the trilogy, that totalitarianism is the only answer. Does that sound at all familiar? Does it perhaps sound like certain members of the Republican Party rejecting democracy and freedom of the press in favour of Project 2025? And yes, it most definitely sounds like something coming out of 中国, but it’s equally at home in the West, and I happen to be mentioning the US Republican Party here but it applies just as much to many other Western countries, including Britain.

You may have struggled with my incessant use of 汉字 in this post but all that really is, most of the time, is a way of transcribing ideas into ideograms like our &’s and @’s. Just as we might look over at that country and think that the Central State has essentially foreign ideas based on the thoughts of “Chairman” Mao, we might also imagine that the capitalist West is free from such things. But it isn’t. It suits the West just fine actually. Nor is the Central State in any wise Communist, because by definition any economy with a stock market isn’t Communist. It’s just as capitalist as we are and it’s actually better at it, to the extent that certain people could learn from them how to be even more capitalist than they are already. Oceania has always been at war with Eastasia.

We are aware that encounters between White people from Western Europe and racialised people elsewhere, such as in Afrika, the Americas and Oceania, have not generally ended well for the latter, and this has often been associated with a mismatch in technology. We might attempt to deduce that this is also what would happen if another species from elsewhere in the Universe with superior technology encountered humanity. However, that makes the rather major and unwarranted assumption that aliens are like us. This is unlikely, partly because they’re alien but also because in this scenario they’ve reached another star system. It also assumes that the greed and materialism dictated by the European-derived economic system is a law of nature and that there’s no other way things can proceed.

This, though, is how I see things going. Here we are on Earth with increasing threats to our civilisation, mostly self-inflicted, such as the use of weapons of mass destruction, anthropogenic climate change and artificial intelligence, among other more prosaic problems. In the meantime, we haven’t been back to Cynthia for over fifty years and there’s no sign of us building large space colonies or going to Mars. Hence we’re missing out on the Overview Effect, or Arthur C Clarke’s ‘Rocket To The Renaissance’, both of which could stand a good chance of changing global consciousness, we have no orbital solar power stations which could satisfy all of our energy needs and enrich Third World nations around the Equator, and various calamities could, and probably will, befall us which space exploration and settlement would’ve prevented. On the other hand, suppose a civilisation out there somewhere has thriven and got past this, or hasn’t got itself into such a pickle in the first place. Those are the kinds of civilisation which we’re likely to end up contacting, because the others simply aren’t viable. Which kind of civilisation we are remains to be seen to some extent, although I know which one I think we are. Or maybe every species of this kind just ends up annihilating itself.

The attempt to contact aliens depicted early on in this series and book is an act of hope, of optimism, which is depicted as bringing down utter catastrophe upon the world. Well no, I’m not going to adopt that view, particularly when it seems to suit certain social forces exceedingly well. I prefer the other. Hence if technological cultures exist elsewhere, they would be of the following kinds: unable or unwilling to leave their planet and perhaps quite healthily uninterested in doing so, in which case they’re not a threat; capable of space travel but also wiping themselves out before leaving their solar system, and yes those would be hostile but are not a threat; able to leave their systems but unwilling to contact us for various reasons; able to leave their systems, peaceful, coöperative and friendly. Or, there could just not be any intelligent life anywhere else. Any of these options has nothing to do with the Dark Forest, is more inspiring than that and is less likely to be useful for political oppression. So there!

The Continuation Of Political Theory By Other Means

There are certain issues with certain people’s opinions of certain works. Consequently I’m going to push the details of what this post is about exactly beyond the fold, but not beyond the pale.

The only thing I know about Carl von Clausewitz is that he said “war is the continuation of politics by other means”. He also said “the best form of defence is attack”, “the enemy of a good plan is the dream of a perfect plan” and “to secure peace is to prepare for war”. However, this post is not about von Clausewitz. It’s about two fairly famous related works, one based on the other, both fairly thoroughly misunderstood and one also unfairly dissed: ‘Starship Troopers’.

Up front I’m going to say that I disagree strongly with the political philosophy of Heinlein’s novel although I do have quite a bit of sympathy with the idea. As for the film, something terrible seems to have happened to its reputation, and bearing in mind that Verhoeven is also reponsible for ‘Robocop’, also quite misunderstood, and ‘Total Recall’, it’s fairly obvious that if you think he meant for it to be a pro-totalitarian or pro-Fascist film, you’ve got it completely wrong. There’s also the issue of identifying what Heinlein intended with Fascism or even totalitarianism and whether it’s a thought experiment or direct advocacy for his political beliefs. The whole thing is a bit complicated really.

Just to introduce the two then:

Robert A Heinlein is a front-ranking English language science fiction writers of the mid-twentieth century CE along with the politically very different Isaac Asimov and Arthur C Clarke. Among other things, he wrote military science fiction, and I’ve found everything I’ve read by him to be very readable and a page-turner. However, I haven’t read much of his work because he has a reputation for being right wing. Asimov is a liberal and was even invited to join the Communist Party, which he turned down. Arthur C Clarke has a religious bent and was heavily influenced by Stapledon, and is of course British. Heinlein supported the Vietnam War, although he also ran for office as a Democrat as a young man. He’s influenced, as are many other SF writers, by his experience of the Second World War. He served in the Navy during the previous decade and as an engineer in the War itself. Like many other people, he drifted to the Right as he got older but unlike some others, he was always politically active, from his Democratic years in the 1930s at least up to 1959’s ‘Starship Troopers’. He believed very much in military government. However, weirdly, his ‘Stranger In A Strange Land’ was very popular with hippies and the counterculture, and he regarded himself as a libertarian who was close to being anarchist. He has a beguiling talent for making his worldbuilding seem believable and reasonable to the reader. I have a sneaking admiration for his work even though his politics are in some ways very distant from my own. He’s also very character-centred and “human”. A better word borrowed from this century’s parlance might be neurotypical.

‘Starship Troopers’ is one of a series of his works driven by a political perspective, and it’s arguable whether it’s his or not. He may simply be setting up an idea and seeing how it works through the plot as a thought experiment, but my impression is that he takes it pretty seriously and I think it probably is what he actually believes. I’m not familiar enough with his writing or life to say too much from an informed perspective. I’ve read ‘I Will Fear No Evil’ and ‘The Door Into Summer’, ‘Beyond This Horizon’, ‘The Number Of The Beast’ and I’m not sure what else. The first is actually quite a strong influence on my view of the nature of personal identity, so there we have it, a right wing author forms a plank of one of my most fundamental philosophical stances which has a major influence on my life and those of the people around me. That novel is the reason I disagree with Derek Parfit’s views. He’s considered the most important and seminal writer of genre SF, establishing many of the central tropes of what outsiders tend to think of as science fiction. Heinlein’s heroes tend to balance the physical and the mental in that they don’t shrink from using violence but are also powerfully intellectual. Being close to pacifism, I hope I don’t need to state that I disagree strongly with the specifics here but also consider one of the major virtues of Yoga that it does the same, though very differently.

‘Starship Troopers’ is influential in two different ways. As well as its political theory, it was a factor in the establishment of the Mecha subgenre of Anime, although Gerry Anderson is also an influence here. Besides that, I would say it promoted military SF, although in a way that’s part of the same thing. The powered exoskeleton, a wearable machine that enables one to exert greater strength than one would alone, already existed before 1959, the year the novel was published, but would probably not have been so widely adopted without his work, for better or worse. But today I want to talk about the other influence.

I get the impression I’ve mentioned this before on this blog, so forgive me if I’m repeating myself (apparently I am to some extent). The basic premise of the novel is that in order to vote, one must serve in the military for at least two years, and violence is seen as a legitimate solution to problems. The reason for this is that liberalism ruined society and it was basically scientifically established that violence had a rightful place in human affairs. It’s probably obvious that I completely disagree with this but at the same time I find his views and the way he illustrates and argues for them fascinating. The novel is partly a propaganda piece defending the Cold War and using the aliens as a symbol for Red China, but it goes deeper than that. Heinlein clearly maintains that there is something central to human nature which makes it impossible for Communism to work, and that for us, a species for which Communism would work would seem utterly abhorrent and a threat. It’s like our instinctive dislike for insects is linked to an innate repulsion to socialism. And that’s interesting, because apparently research has shown that Right wing people make a stronger connection between disgust and moral judgement than Left wing people. I would disagree with this to some extent because I think there are different ways to be Right wing and some of them have nothing to do with prejudice against marginalised groups, at least consciously, and to say they have subconsciously is to presume to know the minds of the people with these views better than they know themselves, which is quite an arrogant position unlikely to lead to empathy and therefore any kind of helpful dialogue. It is nonetheless interesting that Heinlein makes this equation.

I’m not interested in defending a slave-owning democracy. That said, the democratic nature of ancient Athens meant that the people voting for or against war were doing so in the full knowledge that it would be their own lives on the line if they chose to pursue a belligerent policy. This is no longer the case in Western democracies. Nowadays, people who join the military are unlikely to get anywhere near the levers of power unless they’re already privileged. There was a time when the monarch led their troops into battle, but this seemed to end because of the risk to a particularly valued member of society, and at a time when the fate of millions was tied up in that individual’s fate it did make sense to stop doing this, regardless of the wisdom of having such a social order exist in the first place. If that’s a given, it is a rational decision, but it means that the choice of life and death can be made without personal risk. This is the central issue in the novel. In order to earn the right to vote, one must be prepared to put one’s life on the line to defend the body politic.

It’s also light years away from my political beliefs, but precisely because it’s so radically different, the questions asked are in the same realm as my own. My personal belief is that political obligation cannot be derived legitimately but is instead imposed by force, by a government holding a monopoly on the threat of violence. We’re born in territories claimed by governments which most people have never freely consented, because there is no way of opting out without severe personal cost in financial or other terms. There is no hospitable place to which one can move in order to avoid the coercion of government. There are the high seas, Antarctica and war zones, and that’s probably it for this planet. Of course, one reason those places are inhospitable is that there’s no state or other organisation making them more habitable, but when that happens, there are strings attached. It’s a valid argument to say that your life depends on the state, because for example one might be born in a hospital run by the government, go through schooling provided by it, be protected from the threat of violence by a police force and eat food brought to you by road and rail built by them. There’s also the question of compromise, because the chances are nobody will agree with you politically 100%, so you have to comply with the law of the land even if you weren’t a member of the party which brought a particular law into being and would never vote for them. The law also often coincides with morality. I don’t actually think it would be okay to kill or steal, or for that matter drive dangerously, which in my case actually means driving in any way at all. Nevertheless, there is no other choice, and the absence of that choice means that the only ultimate reason to obey the law is that it’s enforced by potential violence and loss of freedom, and in some countries loss of life.

Heinlein poses the right question but gives the wrong answer. His answer is diametrically opposed to mine. He has one of his protagonists express the opinion that violence is often the answer, which I disagree with, but I agree with his opinion that exercising the franchise is in a sense a form of violence. I do vote. In doing so, I’m not entirely pacifist (and incidentally therefore not entirely vegan, which is close to pacifism) because I am engaging in action which endorses the state’s monopoly on violence. Heinlein, amazingly, has got this absolutely right. Of course, the alternative of not voting is irresponsible and the powers that be can sometimes be very keen on the idea of people not voting and therefore it may be in their interests to encourage cynicism about politicians as public servants, because that way one loses the ability to discriminate between better and worse politicians and the actual point of having a democracy, such as it is. However, I’m not completely pacifist anyway because I honestly believe violence was the only way Nazism could be defeated and I don’t want to impose my values as a privileged White Westerner on other, more heavily oppressed people whose experience has led them to conclude that armed insurrection is the only effective answer. After all, it doesn’t actually make their violence less legitimate than that of the armed forces, and there’s moral complexity in both.

Heinlein’s system works in detail like this: you are not born destined to have the right to vote. At the age of eighteen, everyone of sound mind can make the free choice to serve in the armed forces for at least two years, during which they have no freedom. If war breaks out during this period, this is extended for the duration of the conflict. Even a blind paraplegic can serve, although it would be hard to find tasks for which they’re suited. Because of the wide range of abilities, the government has had to provide some kind of work, usually dangerous and unpleasant but always necessary, for every potential citizen. Once one’s term of service is over, provided you haven’t been killed, you not only have the right to vote but the obligation to do so unless you break the criminal law. However, any interruption of service will permanently lose you the opportunity even if you sign up again.#

Now, this has been compared to fascism, and the absence of possible other forms of service which can’t be integrated with the armed forces is ignored. It means that a pacifist has no right to vote, which to Heinlein’s mind is entirely fine because a pacifist doesn’t have the defence of a democratic government as their highest principle. Of course it isn’t actually fine and it assumes that every member of society benefits enough from the social order to defend it. To be fair, the society in question is depicted as having no racism or sexism as Heinlein understands it, although of course this is to the mind of a White male American living in the mid-twentieth century and in fact there are sexist and racist elements in the book as written. In some situations, women are seen as more suitable for particular front line rôles in the military, such as spaceship pilots, because they’re more able to stand the G forces involved and are usually smaller than men, but they also need to be good at maths to do this, and again there’s no suggestion that they wouldn’t be just as capable as men. Racism is seen as small-minded and excessively focussed on local concerns. I mean, he does try, and his society is in fact one where ethnicity and gender are not barriers to success or enfranchisement so this could be fair given his assumptions. Whether it’s possible to get there from here is another question.

Non-citizens are not considered intellectually or morally inferior. These are people who can’t vote because they have not done military service. They do, however, pay tax, so this is taxation without representation. That said, being a taxpayer does give one some rights as to how the government spends one’s money and you can be wealthy and entrepreneurial, and have high status without also having the right to vote. Non-citizens may regard involvement in politics as a dirty business they don’t want to be involved in, and this is quite a common attitude in liberal democracies generally. The government and armed forces don’t encourage people to join up. If anything, they discourage them. They’re given forty-eight hours leave as a cooling off period immediately and many of them never bother coming back, which bars them forever from citizenship. They place severely injured ex-combatants as recruiting officers in order to demonstrate the potential price of service. Future citizens absolutely go into this with their eyes open, so to speak, and it’s very much a free choice.

This is also very much a society in which veterans are respected, which contrasts starkly with our own. There aren’t likely to be any homeless vets here, for example. Not only is a very large component of adult society ex-forces, as was the case with men in the post-war era probably somewhat formative in Heinlein’s thought in preparing the novel, but also they’re generally fairly respected, except for the fact that politics is considered by many non-citizens as getting one’s hands dirty and therefore not particularly worthy of respect. Also in this society there are as many female veterans as male, so there is less balance there among those who can vote. The brutalising effect of being trained to kill and the tendency to make irrational decisions in the heat of the moment which then become set in stone because of the high price paid for them, such as the death of one’s friends or one’s own serious injury. People who haven’t been through this psychologically damaging experience have no say in how the world is run.

On the other hand, Paul Addison’s ‘The Road To 1945’ made the case for the Second World War causing the rise of the welfare state and the NHS. Rico, in the novel, is from a rich background but is treated just the same as everyone else, and it’s been claimed that the mixing of people from different social strata led to a fuller appreciation on the part of the more privileged of the lot of the lower orders. There was also more trust in giant publicly-funded projects. One thing I’m interested in but haven’t looked into yet is whether there’s a connection between the large governmentally-organised hospitals and public servant healthcare workers who must have existed at the time, and the establishment of the NHS. Maybe a society run entirely by veterans would have this aspect to it as well. It led to a historic Labour victory.

This society, then, doesn’t seem fascist. Even so, the implicit attitude to pacifism does come close. One’s supreme duty is seen as being to the state, which is the simple definition of fascism I feel most drawn to, although I admit that’s because it’s simple and not because it’s accurate. But as far as I know we don’t get to find out if it’s pluralist or not. It’s possible that there are no longer political parties because government aims at unity of purpose, which means in a sense that it’s a one party state. We do, however, know that it isn’t Communist, because the Pseudo-arachnids are portrayed as Communist and suited to it, and there are clearly private big business ventures. Pseudo-arachnids are contrasted with humans. They are portrayed as a perfectly communist society and were a stand-in for the Maoist Chinese government and possibly people in the book, except that in reality Heinlein seems to have seen Communism as unsuitable for the kind of organism which human beings are, so if anything Pseudo-arachnids are more Communist than any human group could ever be. The novel also has the Skinnies, humanoids in league with them initially but possibly through mind control rather than willingly and who switch sides later on.

The Bugs are not like us. The Pseudo-Arachnids aren’t even like spiders. They are arthropods who happen to look like . . . a giant, inteliigent spider, but their organization, psychological and economic, is more like that of ants or termites: they are communal entities, the ultimate dictatorship of the hive. Every time we killed a thousand Bugs at a cost of one M.I. it was a net victory for the Bugs. We were learning, expensively, just how efficient a total communism can be when used by a people actually adapted to it by evolution; the Bug commissars didn’t care any more about expending soldiers than we cared about expending ammo.

Hence Heinlein, or at least Juan Rico, believes that humans are not adapted to thrive under a communist system. As an ex-Stalinist, I can remember sympathising with Stalin’s idea that it was worth sacrificing a whole generation of the human race for utopia, but I don’t believe that he was trying to do that. That is, I’m sure he was persecuting a generation of the Soviet peoples (plural) but not for the sake of utopia in the long term.

The Pseudo-Arachnids (I’m not calling them “bugs”) have certain features which makes it “okay” to be speciesist against them. I’m pretty sure Heinlein is on record as saying that we will find that there are intelligent life forms in the Universe whom it’s practically our duty to exterminate because they will be essentially inimical to the human race. Making something look and behave like a giant arthropod stimulates the human disgust instinct as expressed in Torah with its list of treyf animals (but for locusts, probably because they eat all the crops so we may as well eat them). If you start with a real human target for racism and use it for propaganda purposes to distract and divide the populace, you have to impose negative stereotypes on a pre-existing set of individuals, and it’s therefore important to prevent people from getting to know them and realising they aren’t as they’re portrayed or a mass of individuals, but the Pseudo-Arachnids are carte blanche. Heinlein can write whatever he wants about them and they plainly are the “yellow peril”. But this presumably means that back in the twentieth century, in his real world, he can see that Communism isn’t working for them because they’re human and have the same proclivities and instincts as WASPs. For the purposes of the novel we can be confident that Red China could not endure because of human nature, which not only prevents Communism from functioning properly but also leads to its downfall. This is actually quite historically deterministic, which is a fixation of Marxism. For the Federation, history does have a direction and a scientific basis. It just doesn’t go in the direction of Communism.

There is plenty more to say about the novel, but its influence means that it’s also worth moving on. It’s said to be responsible for the Mecha (メカ) subgenre of anime, also known as ロボットアニメ (robotto anime) such as Neon Genesis Evangelion, and of course it also has a manga version. Indigenous Mecha pre-dates ‘Starship Troopers’ by a couple of decades, but was clearly influenced by both ‘Thunderbirds’ and the novel. There is, for example, an OVA mecha anime based on it called 宇宙の戦士 – Uchuu no Senshi – ‘Warriors of the Universe’. There’s also a board game released in 1976 and re-released as a tie-in to the film, a tabletop game, possibly an RPG, and of course the film and its apparently execrable sequels, a TV series and a 21st century video game. The only one of these I’m familiar with is the first film. I don’t want to judge the sequels without watching them but I also don’t want to watch them. The first sequel has a rating of 3.6 on IMDb, which isn’t encouraging, but of course everyone else can be wrong. I suspect what they’ve done with the sequels is cash in on the misinterpretation. I also think there’s a myth established that when the first film came out, it was misinterpreted as pro-fascist. This didn’t happen in my recollection, and I think I’m going to have to address this before anything else.

2020s fans of the film seem to make the claim that it was initially seen as almost fascist propaganda and a bit brain-dead. This, I think, is a kind of superiority thing we get nowadays where, to quote Professor Frink of ‘The Simpsons’, “No you can’t play with it! You won’t enjoy it on as many levels as I do.”. This is pretty sucky, and doesn’t reflect how it was actually received at the time. When it was first released, it was seen in the context of other Vehoeven films such as ‘Robocop’ and ‘Total Recall’. They all have a kind of grey clunky look to them, which I don’t think is merely due to contemporary influence. His films do seem to have a tendency to be misunderstood though. They’re kind of brainy action films. ‘Robocop’ is about the dehumanisation brought on by masculinity, rampant capitalism and corporate power. ‘Total Recall’ is about identity, capitalism and the nature of reality. There are other films of his I haven’t seen with more sexual themes and I don’t know about those but ‘Starship Troopers’ is in the same vein as the two just mentioned. Verhoeven has said that a major theme is that “war makes fascists of us all”. That was also how it was understood by many viewers at the time, though not all.

In a sense, the film isn’t so much about Heinlein’s philosophy as expressed in his novel as the circumstances likely to give rise to belief in such an ideology, or perhaps the result of a society run along those lines. It basically makes you root for fascists, then confronts you with the fact that it’s done so and gets you to ask yourself why. It brings out one’s inner fascist and criticises her. Several interludes in the film take the form of propaganda films modelled after ‘Triumph des Willens’ and ‘Why We Fight’. Like the novel, it’s a Bildungsroman, or rather a coming of age film in this case, following several teens out of high school, all of whom enroll in the forces and pursue their careers very successfully. Verhoeven only read something like the first two chapters of the book, so some people argue that it can’t be a real adaptation. It’s also been compared to ‘Full Metal Jacket’.

One of the major influential innovations in the novel, the powered armour, is completely absent from the film. There are many other differences, but there would probably have to be because the novel is a lot more cerebral. The film definitely goes for deliberate corniness. The initial flashforward is to the barren Pseudo-arachnid homeworld Klendathu rather than an urban Skinny environment. The mobile infantry are lower-tech. Carl is not psychic but is an electronics genius. Dizzy is female and doesn’t get killed in the first chapter. This actually changes things quite a bit as in the book the women are pilots, not ground forces. Rasczak survives well into the second half of the film rather than having died in the backstory and is merged with the teacher character Dubois. The film Johnny Rico is from Buenos Aires along with his family and both his parents get killed in an asteroid impact, along with the rest of the population of the city, giving Rico, Dizzy, Carmen and the rest a major personal grudge against the Pseudo-arachnids. In the novel, Juan’s father joins up because his wife was killed in the attack on Buenos Aires and Rico ends up as his commanding officer. The Pseudo-arachnids are generally less intelligent although there is a more intelligent caste.

It feels to me very strongly that in the film, the asteroid strike on Buenos Aires is a false flag operation to start an aggressive war against the Pseudo-arachnids. Klendathu is on the opposite side of the Galaxy to Earth so the asteroid would have to travel 80 000 light years to get to us, leaving ample opportunity for interception, and it doesn’t make sense that the asteroid would be sent from their system rather than be perturbed in this one to hit Earth. The attack on Klendathu, I also suspect, was deliberately lost. They engineered an attack on the home world in order to guarantee three hundred thousand deaths and provoke the human race into hatred and xenophobia. But maybe not. Maybe the government simply underestimates the abilities of the aliens due to its own xenophobia.

The young and central characters are all pretty people and we’re made to care about them. This establishes a deliberately superficial æsthetic contrast between them and the Pseudo-arachnids, so there’s an implicit criticism of the audience’s prejudice. What appear to be tactical shortcomings in the film may not be. There’s a planetary asteroid defence system which is not used against the asteroid which destroys Buenos Aires. The news report is deliberately gory. The Federation clearly doesn’t want the war to end. However, the society itself is remarkably egalitarian. The new Sky Marshall (i.e. Federation president) is a Black woman, there’s a mix of ethnicities who are clearly equally treated and the mix of women and men in the military and society is clearly not gender-based, less so in fact than in the novel. Violence between humans is considered normal and acceptable. There are public executions. Perhaps one of the interesting differences in the film is the emphasis on media manipulation.

Social Darwinism is a theme. One of the catchphrases is a quote from a real soldier in the book:

Come on you apes! Do you want to live forever?

– Unknown platoon sergeant, 1918.

The battle wipes out less suitable soldiers and the upper ranks of the military carry out their own eugenics by using live ammo in training exercises and shooting cowards in the battlefield. The centrality of the heterosexual romantic relationships is also about breeding in the long run. A parenthood licence is also mentioned, which is a bit strange since Rico’s parents are non-citizens.

It’s never clear what one should do when one produces a cultural artifact which is open to being taken in a way which conflicts with one’s values. One doesn’t want to talk down to one’s audience, viewership or readership, and Verhoeven doesn’t, but the result is that it has tended to be taken in a way which is opposite to his beliefs. Two other films seem to stick out as fitting into that category quite easily. There’s ‘V For Vendetta’, which seems to be taken as a rallying cry by Conservatives, and an older film, ‘They Live’, which is taken by neo-Nazis as an allegory for a Jewish conspiracy to run the world. It’s difficult to know what to do with these takes. In some cases, they might expose common ground between different political perspectives. It’s like the film is an equation which different variables can be plugged into, but perhaps the misinterpretation of ‘Starship Troopers’ is more about being overtaken by the propaganda-influenced direction than seeing it as a metaphor for different political views.

By forcing us to inhabit the minds of what is arguably fascist, both works probably help us understand one’s enemy, and that kind of empathy is in short supply right now. Consequently, Heinlein’s and Verhoeven’s talents are universally useful and could help us to have a more mutually respectful dialogue about things which matter deeply to us. Therefore, I don’t think it’s going too far to say that both the novel and the film achieve a kind of universality which makes them great and they escape from the prejudices of the author and director. At one point in the film, the Sky Marshall says that we must understand the Pseudo-arachnids in order to destroy them. Maybe we should forget about the second bit and just do the first.

Where Are All The Aliens (Part I)?

Alchemist Hennig Brand looks focused, if maybe a bit drained, in this 1795 painting by Joseph Wright. The painting depicts Brand’s discovery of the chemical element phosphorus.

I have repeatedly, perhaps incessantly, referred to the Fermi Paradox on here, but one thing I have never done is to do a survey of the most often given explanations, plus a few less common ones, so I’m going to do that here.

Before I start, it’s probably worth stating clearly what the paradox is. It goes like this. There are thousands of millions of stars in this galaxy, and innumerable galaxies in the Universe, and many of those stars are suitable for life-bearing planets, yet we never seem to detect or encounter any intelligent aliens. Why is this?

Before I get going, I want to mention the Drake Equation. This is a surprisingly simple equation thought up by the space scientist Frank Drake in 1961 CE. It’s simply a series of factors, all unknown at the time, multiplied together. It looks like this:

To explain the variables and the unknown constant N then, N is the number of civilisations with which communication might be possible in this galaxy. This figure is arrived at by multiplying the following factors:

R_* is the rate of star formation in this galaxy.

f_p is the fraction of those stars with planets.

n_e is the average number of planets which can support life per planetary system.

f_l is the fraction of planets on which life appears at some point.

f_i is the fraction on which intelligent life develops.

f_c is the fraction of intelligent life which develops technology making it detectable from elsewhere in the galaxy.

L is the length of time detectable signs are there.

There is said to be a problem with this equation first of all, which is that it’s susceptible to chaotic influence. The Club Of Rome released a report called ‘Limits To Growth’ in 1972 which predicted that various mineral resources would run out very quickly, but this didn’t come about because at the time it wasn’t appreciated that the results of a mathematical model often depend very sensitively on the exact values of the variables involved, now known as the Butterfly Effect. It’s been suggested that the same issue appies to the Drake Equation, in that most of the variables are not even approximately known, let alone exactly. And there’s another problem, which I’m going to illustrate with something personal. I used to have a list in my head of the ideal partner, and there weren’t many criteria on it. It amounted to similar values, personality traits of particular kinds and common interests. A short list. I stopped taking this approach eventually because I decided it wasn’t ideal for a number of reasons, but I also noticed something quite odd. There was one person who was absolutely ideal in these respects, and was also unavailable, so I began to look elsewhere, and was surprised to find that after many more years there wasn’t even one other person who satisfied those criteria even remotely. Don’t worry about me, by the way – I took a different approach and it worked out fine. The same phenomenon afflicted the a particular army when it attempted to produce a small range of uniforms somewhat suitable for everyone. Given criteria such as arm and leg length, chest and hip circumference and the like, all quite important for the clothes to fit, they found that nobody at all had the same such dimensions, and it was impossible. I’ve mentioned this before of course. Applied to this equation, it’s easily conceivable that working through all the variables, if they were known, could result in N equalling one, namely us humans here on Earth, and that’s it. Some of them are much better known now, or at least f_p is: there are a very large number of stars with planets, probably most of them in fact, and the ones which don’t have them would be unsuitable for life anyway because they’re short-lived and life doesn’t have long to develop on them anyway. There also seem to be examples of planetary systems in which multiple worlds are suitable for life, such as TRAPPIST-1, with at least three planets orbiting within the habitable zone. The wording of the Drake Equation is also somewhat inappropriate, as it fails to take into account that moons might also be suitable for life. These increase the value of n_e considerably. f_p is effectively close to one, and n_e is quite possibly quite high. For instance, in this solar system it could be as high as 8 if moons are included. The presence of life on, or rather in, moons is, incidentally, one possible answer to the Fermi Paradox.

Using the information available at the time, Isaac Asimov worked his way through the equation in his 1979 book ‘Extraterrestrial Civilizations’ and concluded that there were 530 000 such civilisations in the Milky Way. His approach was quite exacting. For instance, he excluded the nine-tenths of stars which are in the galactic core and assumed that the total length of civilisations per planet averaged at ten million years, but was shared between different intelligent species evolving on the same planet. On the other hand, the book was written before it was realised that the Sun would make this planet uninhabitable æons before it would start to become a red giant. I think Asimov’s approach was a little tongue-in-cheek, but there is an issue about whether once intelligence evolves, it will ever disappear again on a planet until it becomes uninhabitable. We may also be in a position where once evolution enters a certain state, the appearance of the kind of intelligence which leads to technology may occur repeatedly. It’s been noted that there are a number of other primate species which now use stone tools, for example, and the nature of intelligence among crows, parrots, elephants and dolphins as well as primates is quite like ours. Given that Asimov’s estimate is exactly correct, which is unlikely, this makes it possible to estimate the average distance between such civilisations. The volume of the Milky Way Galaxy has been estimated at eight billion (long scale) cubic light years. The central nucleus, according to Asimov and others, is unsuitable for life, so assuming that to be spherical, which it isn’t of course, that gives the rest of the Galaxy a volume of around six billion long scale cubic light years. If there are 530 000 civilizations in that volume, that makes one per eleven million cubic light years, so that would make the average distance between them roughly 224 light years with spurious accuracy.

I’m actually going to do headings this time!

Absent Aliens

The most straightforward, and in a way even the most scientific and sceptical explanation, is that Earth is the only place in the Universe with life on it. There are various versions of this, but the simplest is just that life arose on this planet by sheer luck, and is practically impossible. Nowhere else in the Universe is there so much as a bacterium. Since we only seem to have one example of life known to human science, this is the only explanation which doesn’t rely on conjecture. At first sight, it might seem unlikely that there’s no life anywhere else although strictly speaking life would only need to be rare for this to be the explanation. There is in fact a peculiar issue with the origin of life on this planet. Although taking a few simple compounds as would’ve been found in the primitive atmosphere and oceans and exposing them to ultraviolet light and electricity does produce many of the more complex chemicals found in living things, there is an important set of compounds which are completely absent. DNA and RNA are very complex of course, but are made up of fairly simple building blocks of ringed nitrogen-containing compounds called purines and pyrimidines which comprise the rungs of the ladder and encode the genetic information. As far as I know, such compounds have never arisen in laboratory conditions. Clearly living systems can all synthesise them or they wouldn’t exist, but this happens through complex enzymes and already-organised biochemical pathways which rely on genes, made of those very same compounds. It’s a chicken and egg situation, and perhaps this means that the appearance of purines and pyrimidines is the single unlikely missing link on the way to life which has arisen just once in the entire history of the Universe, and therefore that the only place in the Universe where there is life is this planet. However, even if this is a one-off event, it doesn’t necessarily entail that life is found only here because it may still be that it arose somewhere in the Universe and spread widely. A few million years after the Big Bang, the whole Universe was much smaller, denser and warmer, to the extent that all of it was between the freezing and and boiling points of water and matter was dense enough to support life as we know it in space, and the elements from which it’s made were already available. Hence it’s possible that life has been around for almost as long as the Universe, and that it has a common origin, being able to spread as the Universe expanded.

There are even hints that life is present elsewhere in this Solar System. Some people, myself included, interpret the 1976 Viking missions’ ‘Labeled Release Experiment’ as positive in detecting life. This involved taking a sample of Martian soil (I always find it strange when extraterrestrial materials are described as soil. Martian soil is more like a mixture of rusty talcum powder and bleach), exposing it to a radioactively labelled soup of nutrients in water and measuring any carbon dioxide given off for radioactivity. It assumed that water would not be harmful to any organisms living in the soil. Anyway, the experiment was positive, but cast in doubt in view of the fact that the other two were negative. On Venus there have been three separate pieces of evidence for life in the upper atmosphere, not just the claim of phosphine. There is also something in some clouds which absorbs ultraviolet light and a compound called carbonyl sulphide is produced which is difficult to account for in the absence of life. On one of the several moons in the outer Solar System with subterranean water oceans, Saturn’s Enceladus also has geysers in which biochemical compounds have been detected. Other candidates include Titan, Europa, Ganymede and Callisto, and perhaps Jupiter. However, I don’t think this is good evidence for life elsewhere in the Universe. I think it could easily turn out that if there is life in these places, it has spread out from a common origin somewhere in this Solar System and without good data from elsewhere in the Galaxy we might still be alone apart from that.

One argument for life being common is that it began so very early on this planet, very soon after it first formed in fact, which makes it seem almost inevitable given the right conditions. Alternatively, it may have infected this planet from elsewhere, possibly Mars. However, this doesn’t follow because we only have one example of life known to us. There is also a very specific reason why life might be rare or non-existent elsewhere: phosphorus.

Back in the day, Isaac Asimov (yes, him again!) scared the living bejesus out of me in his article ‘Life’s Bottleneck’, highlighting a peculiar and largely ignored major environmental problem. There are all sorts of chemical elements needed for human life of course, but the major ones for all life make a short list: carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus. Phosphorus is far less abundant than the others and living things are distinctive in that they concentrate phosphorus way more strongly than the other elements compared to their surroundings, on the whole. The way industrial societies tend to deal with human excretion is often through sewers which expel the treated waste into the water and ultimately the sea. This waste is of course quite high in all sorts of elements, but is also sufficiently high in phosphorus that the alchemist Henning Brandt was able to discover it in the seventeenth century from performing transformations on human urine, as in the picture opening this post. The phosphorus which enters the sea only returns to the land very slowly because it’s mainly recycled by continental drift and gets washed off the land by rain anyway. Humankind began to notice in the early nineteenth century that the limiting factor in food production was phosphorus, and proceeded to mine phosphate rock for fertiliser, which has liberated a lot of phosphorus into the environment and leads to algal blooms and the like, which tends to poison the oceans and deprive aquatic environments of oxygen due to increased biochemical oxygen demand. It’s hard to know exactly what anyone can do about this which would make much difference, but a few steps which could be taken are to increase the amount of food from marine sources in one’s diet, which doesn’t mean fish, crustacea and the like because of their unsustainable “mining” but seaweed, and change the way one gets rid of urine, fæces being more a public health hazard which would probably be best dealt with by sanitation services, which does however need to happen, so that is a lobbying and pressure group-type issue. Anthropogenic climate change is of course vastly important, but it’s only one of various vastly important environmental issues, and the phosphorus one in particular is disturbingly ignored. Things are far from fine in that area.

Phosphorus limits biomasse. It’s the limiting factor in it to a greater extent than other elements because they are far more abundant. It might not be going too far to call the kind of life we are “carbon-phosphorus-based” rather than “carbon-based”, because the element has two completely separate but vital rôles in all life as we know it. One of these is that it stores energy and provides a chain for its release from glucose, even in anærobic respiration, in the form of adenosine triphosphate (ATP). This is how the Krebs cycle links with the rest of metabolism. Without ATP, there is simply no life. The other is that it forms the sides of the DNA and RNA molecules along with a sugar, in the form of phosphate. Again, without nucleic acids, there is no life, which harks back to the difficulty in finding a feasible process for purine and pyrimidine synthesis. The discovery that phosphorus was a major limiting factor in biomasse may not simply apply to life on this planet, but throughout the Universe.

Why is this an issue? Wouldn’t we find that other planets in the Universe have about the same amount of phosphorus as there is on Earth or in this Solar System? Well, no, or rather, quite possibly not. Odd-numbered elements are usually rarer than their even numbered neighbours in the periodic table, and phosphorus is element number fifteen. Of the other elements playing a major rôle in life here on Earth, only nitrogen and hydrogen have odd numbers. Hydrogen is a special case because it’s the “default” element. In parallel universes whose strong force is slightly weaker, the only element is hydrogen. Its abundance there is one hundred percent, and most atomic matter in the Universe is in fact hydrogen, because the rule doesn’t apply to it. It’s a given. Nitrogen is still the seventh most abundant element because it’s fairly light and therefore likely to form. Phosphorus is the seventeenth most common everywhere on average, and is only formed when silicon atoms capture neutrons and decay. Only 1‰ of Earth’s crust is phosphorus and 0.007‰ of the matter in this Solar System. Its main mode of formation is in Type II supernovæ.

Supernova 1987A, a Type II supernova in the Large Magellanic Cloud

Type II supernovæ result from the collapse of stars whose mass is between eight and four dozen times the Sun’s. They only “burn” silicon for a very short period of time, during which a few silicon atoms will become phosphorus. Then they explode, scattering their elements across their region of the Galaxy in a shockwave. As time goes by, these supernovæ slowly increase the abundance of various elements, including phosphorus, but the regions of the Galaxy where the element is relatively abundant may be quite small and scattered, at least for now. This means that effectively the Universe, and on a smaller scale our galaxy, may be a phosphorus desert with a few small oases where it is even remotely “abundant”. Asimov said of phosphorus that we can get along without wood by using plastic, without fossil fuels by using nuclear power and without meat by substituting yeast, but because phosphorus is such a fundamental part of our metabolism there is no such substitute.

Now the question might arise of why so much importance is placed on phosphorus here when life seems to be so very adaptable and able to find ways round problems, and this is indeed so, but there are reasons for believing that this cannot happen with this element. It’s locally more abundant in geothermal vents and carbonate-rich lakes, which have fifty thousand times as much oxygen as seawater has, and it can also become concentrated in rockpools due to capturing the runoff from water and concentrating it when it evaporates at low tide, so there are various high-phosphorus places on this planet where life could have begun, which may well not be elsewhere in the Galaxy. Now suppose there are various different processes which could lead to life beginning here which do not involve phosphorus, which seems feasible and in fact it’s considered slightly odd that all life known here seems to have a common origin. The one which needs phosphorus is at a disadvantage compared to the ones which don’t, because it relies on a scarce element and wouldn’t be able to spread so easily to environments where other life for which it was not a limiting factor would be able to thrive. Therefore it very much looks that the kind of life which exists on this planet has the only kind of biochemistry possible here.

This could have major consequences for our own space travel. It might mean, for example, that we can’t settle on planets in distant star systems and thrive without bringing our own massive supply of phosphorus, and this also makes it more difficult for other intelligent carbon-based life forms to colonise the Galaxy, because not only are there vast distances between the stars, as we already know all too well, but even those distances are small compared to the small spheres of phosphorus-rich systems scattered sparsely through the Milky Way. They could be thousands of light years apart. Moreover, although the Universe is very old, it may have taken this long to accumulate enough of the stuff for life to be possible at all, meaning that the idea of elder civilisations out there which appeared æons ago may be completely wrong. This leads to a second variant on the idea that life is rare.

We’re The First

It may be that we don’t know of any aliens because there aren’t any, but there will be one day, either because of us or because they will evolve later. The phosphorus bottleneck is one explanation for this, but it could also be that we got very lucky with evolution. Over most of the time this planet has existed, it’s had life all right, but it was single-celled and those cells weren’t even the more complex ones like amœbæ, and life chugged along just fine, though it didnæ end up producing anything very impressive-looking or even visible to the naked eye. It could very well, for all we know, have continued in that vein until the Sun roasted it out of existence, but it didn’t. In fact this is another explanation entirely which is worth exploring as such: simple life is common, complex life rare.

One way to look at evolution as it’s happened here is as a series of improbable events. Some even say that the advent of oxidative phosphorylation is improbable, and that even anærobic respiration was an improbable step, which would limit life so severely as to effectively rule it out in any meaningful sense. Beyond this, the evolution of cells with separate nuclei containing DNA surrounded by an envelope of cytoplasm with symbiotic bacteria living within it also seems quite unlikely, and we haven’t even got to the simplest animals and plants yet. Maybe on other planets these improbable events have taken longer than they have here, or don’t happen at all, and although there will be intelligent life there one day, that point is hundreds of æons in the future. There are a couple of unexpected things about the Sun. One is that it’s a yellow dwarf rather than a red dwarf, and since those are both apparently suitable for life-bearing planets and liable to last many times longer than the Sun, a random selection of intelligent life in the Universe might be expected to result in finding an organism living on a planet circling a red dwarf 200 000 000 000 years in the future. The other weird thing about the Sun is related to this. If there is something ruling out life on red dwarf planets, such as frequent flares, it’s still more likely that intelligent life would evolve on a planet slightly cooler than the Sun, that is an orange dwarf such as α Centauri B or either of the 61 Cygni binary system, because the star would both last longer as such and have a habitable zone which lasted longer in the same place. Perhaps the reason the Sun is a yellow dwarf is that we are ourselves unusual and have evolved unusually early, so the absence of aliens is in a way connected to the unusualness and apparent unsuitability of this star.

The ‘Red Dwarf’ universe has the second version of absent aliens which in fact amounts to “we’re the first”. There are other intelligences in ‘Red Dwarf’ but they’re all derived from Earth in one way or another, and this is “word of God” because Rob Grant and Doug Naylor have said so themselves. In this version of us being first, we are indeed the first but will go on to seed the Universe with our machines and organisms until it teems with intelligent life. We just happen to be living before that’s happened. I would argue against this for the same reasons as I did here: if that’s the case, aren’t we just incredibly unlucky to have been born before it happened? My answer to this is that it will never happen, but there’s a further probabilistic difficulty in the fact of our existence here and now on this planet 13.8 æons after the Big Bang: the scepticism about our future is about time, but could equally well be applied to space. If I am a random intelligent entity in the Universe and it’s normal for intelligent life forms to expand out and settle the Universe in untold high population numbers, why am I not one of their much greater number? Here’s a possible answer:

Intelligent Life Destroys Itself

This was a popular idea from 2016, when Donald Trump got elected, but has been stated many times, in connection with climate change, the Cold War and hostile nanotech. Maybe there’s something about monkeying around with the world which ends up killing species off. This could be quite low-key. For instance, it’s possible that if we had continued with a mediæval level of technology and population and it had spread around the world, although climate change might not be as severe as a result of our own activities, we might still reduce the fertility of the soil and have plagues and famines wipe us all out in the long run. However, once an industrial revolution has occurred, bigger problems start to emerge, the most prominent and obvious being anthropogenic climate change in our case, but another issue is the use of weapons of mass destruction, or AI, complexity or nanotechnology causing our extinction. The Carrington Event is a famous solar flare in the mid-nineteenth century which led to electrocutions from the only electrical telecoms which existed at the time, telegraphy. If this happened now, and it is likely to recur quite soon statistically, the internet and devices connected to it could be physically destroyed, and we are now very dependent on it. Nanotechnology is another potential threat, with the “grey goo scenario”, where tiny machines reproduce themselves and end up eating up the entire planet. This has been explored and seems to be impossible, because limiting factors like phosphorus for life also exist for such machines in the form of other elements, but one thing which could happen with nanotech which is much cruder is that it simply becomes a ubiquitous particulate hazard for everyone. Complexity probably amounts to unforeseeable apocalyptic scenarios. For instance, climate change could lead to wars over water which would restrict access to metals needed to maintain a physical infrastructure we need to provide food. In a way, as an explanation of the Fermi Paradox the absence of aliens might constitute an important lesson for us, but the details are less important than the consequences, which are that there are no spacefaring or communicating aliens because they always die out soon after becoming capable to doing anything like that.

I actually do think this explanation has some factual basis, although it isn’t quite as drastic as it seems. I think there is a brutal pruning process in technological and social progress which prevents harmful aliens from leaving their star systems, and unfortunately in that process there are myriads of innocent deaths and enormous sufferings, holocausts and the like. The way I think it works is that tool-using species may either smoothly develop in a consistently altruistic way or in a more internally aggressive manner which may or may not be resolved by the time they attain the ability to travel through space. We are now at such a crucial stage, and we may destroy ourselves, solve our social problems and opt not to go into space or solve our social problems and expand into space. There may be a law of nature which means an overtly belligerent attitude is self-defeating and such species, although they may not be essentially aggressive, always destroy themselves rather than travel to other star systems. In other words, I believe in this explanation, but it may not be an explanation of the Fermi Paradox. I think it means that any aliens we encounter who have left their own star systems will automatically be peaceful and coöperative. If this is too tall an order then nope, there are no interstellar civilisations, although there may be aliens who haven’t wiped themselves out yet, and even aliens who occupy an entire star system. This is the opposite answer to the Fermi Paradox to the next, fairly recently devised, one:

The Dark Forest

This is named after the work in which it was apparently first suggested,  黑暗森林, by the Chinese SF writer 刘慈欣, Liu Cixin, in the ‘noughties, although it’s hinted at in the preceding novel, 三体, whose English title is ‘The Three-Body Problem’. Avoiding spoilers, the basic idea is that we never hear from aliens not because there are none, but because they’re hiding from each other. I’ve mentioned this before but it bears repeating here. Aliens are assumed to see each other universally as potential threats and will therefore act to destroy each other whenever they become aware of their existence. In response to this, they all hide themselves and the reason we detect no signals from them is that they assiduously avoid making themselves detectable. Against this dark background, humans are recklessly advertising our presence to all and sundry, positively inviting ETs to come along and destroy us, even if only to avoid attention being unwantedly attracted to themselves by even more powerful minds which would swat them like flies.

It can be argued that this situation reflects the real situation we observe in ecology, where camouflage and mimicry protect organisms from each other and disguises of various kinds are adopted to prevent themselves from being sensed, killed and eaten. I think 刘慈欣 has a rational approach to the issue, and in fact quite a positive message as he believes that we’ve got the idea of humans and aliens the wrong way round. He believes that there is a prevailing view that aliens will be friendly while we are aware of the hostility prevailing between powers in the human world, but that the real situation is that human beings are potentially much more altruistic than we give ourselves credit for, and it’s likely to be the aliens who behave in a vicious manner towards us. Other believers in the Dark Forest answer say that non-believers in it are being anthropomorphic by imagining that aliens would not be hostile, because the biosphere we know of is quite savage. I’d say that this is a projection, and also that to extend the comparison, there are circumstances where organisms positively advertise their presence, for example to seek a mate or as warning colouration. The former is a little hard to fit into this scenario, but the closest analogy would probably be something like exchange of information for the benefit of both cultures, a relationship described ecologically as symbiosis. For instance, assuming the presence of multiple hostile civilisations in the Galaxy, it would seem to make sense for two less powerful cultures to tell each other about the threats. Something like warning colouration is another possibility. A species of aliens might wish to broadcast its potential hazardousness to others in order that it not be bothered, rather like the Mutually Assured Destruction (MAD) scenario, and in fact the Dark Forest is based on game theory, which is influenced by MAD.

The idea of more powerful civilisations disrupting and destroying less powerful ones has a persuasive-seeming precedent in human history, because in general European and European-derived cultures have tended to do that to a horrifying degree on our own planet to other human cultures. This,though, is based on what happens within our own species in highly specific circumstances which rely substantially on the idea of territory and land use, along with a religious and political outlook used to justify those atrocities. It’s this which seems anthropomorphic to me. The Dark Forest seems to be the same situation translated into interstellar space and assumes that the species or entities involved are similar to us in the mode we have employed during history, which is likely to be highly atypical even for us, and we may also be projecting our own assumptions onto ecology when we assert these things. There are plenty of examples of peaceful coöperation between species, such as symbiosis and the very fact that multicellular organisms are themselves alliances of unicellular ones for mutual benefit in the same way as an ant colony is. There’s also the consideration that life on this planet has been around for a very long time now and it would seem to make more sense to nip things in the bud before intelligence of our kind has even evolved, but this hasn’t happened. However, I do maintain a modicum of sympathy and interest in 刘慈欣的 argument because I suspect it’s linked to dialectical materialism, and in order to assess it properly I would have to know more about Maoism, the current status of the Chinese 共产主义, his status with respect to the Chinese government and so forth. I would maintain that China, because it has a stock market, is capitlist, but that doesn’t mean it doesn’t have valid philosophical views built upon its ideology. It’s all a bit complicated, and interestingly something he goes into himself in his novels. Although I don’t agree with the Dark Forest at all, laying it out as a Marxist-influenced argument is interesting and may suggest other solutions to the Fermi Paradox which are freer from the taint of capitalism.

Spending Too Much Time On The Internet

I have felt since the early 1980s that there may be a trade-off between Information Technology and human space exploration. I don’t want to go into too much depth here but I suspect there is an inverse relationship between the two, such that the more IT advances, the less effort is expended on sending people into space and the more human beings explore the Universe, the less happens in the sphere of computing and the like. This is a subject for at least an entire post, and I won’t do more than mention it in passing here. Suffice it to say that when the Drake Equation and Fermi Paradox were first thought of, IT was very primitive compared to how it is now, although the internet itself is quite possibly the most predictable thing which has ever happened (see for example Asimov’s ‘Anniversary’ published in 1959 or Old Burkster’s Almanac in the 1970 ‘Tomorrow’s World’ book, which actually predicted the exact year it would take off (1996), so the link could’ve been made then. In fact, Olaf Stapledon predicted something similar in ‘Star Maker’ in 1937, where he imagined a species of aliens which ended up never leaving their home planet, which is doomed due to losing its atmosphere, because they end up lying in bed all day hooked up to a global information communications system, which also tellingly begins by encouraging cosmopolitanism but soon degenerates into echo chambers.

The “spending too much time on the internet” solution to the Fermi Paradox goes like this. We went through the Space Age and appear to have come out the other side. On this other side, we have an almost universally accessible network of devices for information and communication. If we are able to develop sufficiently convincing virtual worlds, we might all end up in the Matrix and not bother going into space at all. Perhaps this is what always happens to sufficiently advanced technological civilisations. The author of the Dilbert cartoons, Scott Adams, once stated that if anyone ever managed to invent the Holodeck, it would end up being the last thing ever invented because everyone would just end up living in that virtual world and not bothering with anything else. This is different to the idea of the Universe being a simulation because in this situation everyone knows where they are is not “real”, although Gen-Z-ers might argue with a definition of reality which divides meatspace from cyberspace with considerable justification, and willingly participates anyway. If you’re doing that, why bother to explore strange new worlds or seek out new life and civilizations. In fact you could do that anyway because I’m sure a virtual Enterprise would be one of the first things to be created in this virtual world, if it hasn’t been already. It wouldn’t be “real” in the way we understand it, but who are we to say? It would, however, mean we aren’t going to meet any aliens because they’re all on Facebook or something, which we may already have noticed is so.

One problem with this answer is that it assumes aliens are all similar enough that they get to a stage when they not only start to create communal online environments but also then get addicted to them and abandon space exploration. It isn’t clear that they’re similar enough even to have the same mathematics as we have, so why assume this is what happens? It may well happen to humans, but that could have little bearing on what happens anywhere else.

This can be turned round:

The Planetarium Hypothesis

There are several different versions of this and it blends into another version. The most extreme and probably easiest to state version is that we are living in a simulation, which Elon Musk claims playfully and perhaps not very seriously to believe. The argument that this is so in his case is based on the expectation that technological intelligences would very commonly get to the point where they could simulate the Universe, and within those simulations, more technological intelligences would do the same and so on, meaning that the number of virtual worlds compared to the real one is very large and therefore that we are much more likely to be living in one of those than the unadulterated physical Universe. Hence this is not the real world, and for simplicity’s sake, or perhaps as an experiment, we’re sitting in a simulation which, unlike base reality, is devoid of aliens. The alternative, according to Musk, is that in the near future we’re likely to become extinct, because there would then be no intelligent civilisations capable of simulating the Universe and therefore that we are living in base reality, but not for very long because there is about to be a massive calamity which will wipe us all out. I don’t find this argument to be at all satisfactory. Like the previous argument, it assumes that history will proceed in the same manner for everyone and that we all end up producing simulations. It also assumes simulations are possible when there are at least two good reasons for supposing they aren’t. One of these is the three-body problem. Three bodies whose attraction to each other is significant will behave chaotically in almost all cases and there are no ways of predicting their movement with a finite number of mathematical operations. There are exceptions to this. A few entirely predictable stable situations exist, most of which are too rare to occur in the observable Universe although there is one which may well exist somewhere in a star system in a galaxy far away. However, that’s the three-body problem. The Universe we experience has many more bodies than that in it. The number octillion has been mentioned in connection with this. For the Universe as we know it to be simulated, even the bits we’ve visited with space probes, an infinitely complex computer would be needed. Another problem is that of consciousness. Simulating consciousness doesn’t seem to be the same thing as actually being conscious, yet we know ourselves to be conscious. We could be mistaken about our substrate – maybe it’s transistors or qubits rather than brain cells – but for that to be so, panpsychism also has to be true, which as far as I’m concerned is fine but most people don’t accept that view of the nature of consciousness. There may be a functionalist solution though. A further objection is based on Musk’s own thought about the multiplicity of simulations. If a powerful computer can run a simulation of the Universe in which other computers can also run simulations of the Universe and so on, the largest number of simulations running would also be the most rubbish ones, at the bottom of the pile, because that’s the point at which the “tree” has its final twigs, and that means we’re more likely to be in a rubbish simulation, but we aren’t, and that simulation would also be too simple to allow any further simulations to be run. Minecraft exists, therefore we are not living in a simulation!

One point in favour of the Planetarium Hypothesis is that it’s highly sceptical and makes very few assumptions compared to some other solutions, and in that respect it’s similar to Absent Aliens. There are also less extreme versions of this which take the word “planetarium” almost literally. We have never bodily travelled more than 234 kilometres into trans lunar space, which happened with the ill-fated command module of the Apollo XIII mission in 1970. Therefore, for all we know the rest of the Universe could be faked for our benefit, although this assumes that the likes of the Pioneer and Voyager probes are just sitting somewhere being fed loads of false data or something. There’s a decision to be made in this explanation as to where one cuts things off and decides everything else is fabricated, and it begins inside one’s own head. This thought has been used at least twice by major SF writers. In the 1950s, Asimov (again!) wrote a story where the first astronauts to go behind Cynthia (“the Moon”) found it was painted on a board and propped up by wooden struts. Later on, Larry Niven, who had written himself into a bit of a corner with his Known Space series because he had to try to maintain continuity, playfully came up with the idea that none of it had happened and it was just being simulated in VR on Cynthia.

It’s been suggested that the almost perfect match between the apparent size of Cynthia and that of the Sun is a kind of Easter Egg, that is, a clue that we’re living in a simulation. It doesn’t seem necessary for the existence of intelligent life here that that match should be so perfect, and there seems to be no explanation for it other than chance. And it is peculiar. It will only hold true for the approximate period during which oxygen-breathing terrestrial animals can thrive here because the distance between Cynthia and Earth is increasing by a few centimetres every year. It would be interesting to run the figures about this, to see for example how big and/or distant a moon would have to be if we were orbiting within the habitable zone of 61 Cygni B or something, because there might be a clue there.

I have to admit it’s tempting to believe that the empyrean, as it were, is hidden from us by some kind of holographic Dyson sphere, i.e. that the planetary Solar System and Kuiper Belt are surrounded by a fake display of the rest of the Universe, just because it’s an appealing idea, and there are even reasons for supposing this to be the case. However, that would mean that Pioneers 10 and 11 along with Voyagers 1 and 2 either hadn’t hit the solid sphere of the sky, as it were, yet, or that they had but are themselves in a simulation of interstellar space. It was recently suggested that the Solar System may be enclosed in a vast magnetic tunnel as it moves around the Galaxy, but it seems to be several hundred light years wide and a thousand light years long, so if that’s the edge of the simulation it seems a bit pointless. Another appealing idea associated with this is that all that stuff about Venus being a hot, steamy jungle planet and Mars having canals and Martians living on it could be entirely true and we’re just having all that concealed from us and, again, fake data being fed to space probes. Of course, if human astronauts actually did go out there this would be harder to maintain, unless one begins to suppose that they’re all abducted and brainwashed or something.

The answer this kind of blends into is the

Zoo Hypothesis

This used to be my favourite answer when I was younger, and I just basically assumed it was true, but it lacks the parsimony of absent aliens or the Planetarium Hypothesis. If you’re familiar with ‘Star Trek’, you’re probably aware of the Prime Directive, also known as Starfleet General Order 1:

“No starship may interfere with the normal development of any alien life or society.“

We don’t know how extensive or organised any technologically advanced species or other intelligence which might exist outside our Solar System is, or anything about their ethics or politics. However, the admittedly anthropomorphic analogy with how things are here with uncontacted people on our planet, we do have at least a rudimentary ethic to protect them. We note that they are self-sufficient, unfamiliar with how things work in global society, highly vulnerable and at risk of extinction. Often the reason their lives do end up disrupted is due to governments or multinationals wanting to get hold of resources which happen to be located where they are. This is never going to be the case for Earth in terms of mineral resources, as even phosphorus is found elsewhere in sufficient quantities, if that turns out to be important, and there isn’t going to be any kind of invasion to get hold of metals or whatever from here. What we may have is culture and biodiversity. Speaking of biodiversity, there are reserves and national parks in many countries on this planet, so maybe we’re in one of those. It isn’t clear whether to an alien we would be more like an uncontacted indigenous culture or endangered wildlife, depending on how different our intelligence and minds are, but there are measures in place here for the protection of both. Moreover, when the difference is large enough, it’s possible for human technology to maintain an environment in captivity which may create a persistent illusion of the habitat an animal is found in before human interference, and we could be in such an environment.

I’m going to present my train of thought, as was, on this issue, starting with the premises of the Fermi Paradox. The Galaxy is more than twice as old as this Solar System, so it’s fair to assume that intelligent life evolved many æons ago, even before the Sun formed. This is also more than ample time for the Milky Way to become thoroughly known to the technological cultures that exist within it, and it can also be assumed that any species able to leave its star system must have achieved some kind of utopia in order to be able to use the energy and resources efficiently enough to do so. Therefore the probable situation across the Galaxy is that a peaceful and benign community exists which will protect the less advanced civilisations found within it. This applies to Earth. We are observed by aliens and there is a non-interference ethic which prevents us from being contacted because of the disruption that has been seen or modelled to occur in the past if it happens too early in the history of a species. This policy has been in place for thousands of millions of years. When we reach a certain stage in technological and perhaps social development (I actually think these always occur hand in hand), we will be contacted and, perhaps after a probationary period, invited to join the “Galactic Club”. There is well-worn standard procedure for doing this. It can also be supposed that because this society is so ancient and long-established that it works as perfectly as any society could, so the procedures can no longer be improved upon. I should probably also mention that back then, as now, I thought in terms of technological cultures rather than species. Individual races come and go in this scenario just like individual humans in society, but the culture is permanent, or at least very durable. This is the condition of the Galaxy.

Although my use of the word “culture” calls Iain M Banks’s fiction to mind, I began to use it before they were first published. The word is just very apt to describe this kind of situation. I used to be very confident that this was how things were, and it is more or less the Zoo Hypothesis. Where it falls down, I think, is in having a quasi-religious tone to it. It could be argued that this is akin to our own ancient tendency to project our wishes and stories onto the sky, and I do think this is significant. However, there are different ways to respond to that thought. One is that we unconsciously know how things are and therefore made various attempts to express that fact given the current state of knowledge throughout our history. Alternatively, the reverse could be true: we have a tendency towards magical thinking which results in religion, and this leads us towards imagining how to have things this way in the face of what we perceive to be powerful evidence against the supernatural. Some fundamentalist Christians accept the existence of aliens but see them as demonic. It’s very difficult to examine oneself closely and neutrally enough to come to a firm conclusion as to what belief in the Zoo Hypothesis is motivated by, and therefore to assess it scientifically or rationally. There are certainly inductive inferences operating within the argument, but perhaps not deductive ones. “Accusing” it of having a religion-like flavour is not the same as refuting it, and part of the decision as to whether to accept or reject it relates to how one feels generally about religion.

That said, there are some ways of arguing rationally against it. It only takes one small group within the Galaxy, perhaps the closer star systems in this case, to behave differently for First Contact to occur. Since I’ve concluded also that mature interstellar cultures must be anarchist, there would be no law enforcers to prevent this from happening. However, anarchist societies are not necessarily chaotic and may have customs which prevent such things from happening. For instance, queues are not generally legally enforceable but people rarely jump them due to social disapproval or the simple act of people providing the service one is queueing for ignoring violators, and there are apparently places where there are no laws regarding traffic priority at junctions, but people behave harmoniously according to custom. It hasn’t escaped my attention that I’m talking about Douglas Adams’s “teasers” here. As far as we can tell, though, this hasn’t happened. Or has it?

UFOs Are Alien Spacecraft

Like most people, I reject this out of hand but there’s a point to stating in detail examples of what people who believe this generally think. There is some variation in the details, but I think it works roughly as follows.

For quite some time now, perhaps since prehistory, this planet has been regularly visited by spacecraft ultimately originating outside this Solar System, containing intelligent aliens. These aliens sometimes abduct humans and other animals to do experiments on them. The governments of the world are aware of the situation but keep it secret from the public to avoid panic or because they’ve made some kind of deal with the aliens.

This view has a number of variants and is the basis of several religions. One such view is that ancient astronauts are responsible for world religions and have interfered in our history, perhaps even interbreeding with our ancestors or genetically engineering them for the appropriate kind of intelligence. Incidentally, this is known as “uplift”. Another view, of course, is that the human world is run by alien reptilian humanoids or shapeshifters for their own nefarious purposes and not for human benefit. There are also notions such as aliens wanting to get elements or substances from this planet which are rare elsewhere in the Universe, such as human enzymes or for some reason gold.

I stopped believing that UFOs were alien spacecraft when I was about ten, I think. There are a number of very good reasons to suppose this is not the case. The initial trigger that ended my belief was that the occupants of the craft were said to be humanoid in possibly all cases, which I saw as completely incompatible with them being aliens. For a while, I believed they were time machines and the beings on board were highly evolved humans from the future. Although I no longer believe this either, I still think it’s more plausible than the alien idea. I had a bit of a blip in my disbelief when I heard about the star chart aboard the spacecraft in the Hills’ abduction, which closely maps nearby star systems from a certain angle, but now think that this could be made to conform to the pattern drawn by projecting the stars in various different ways until a rough fit was achieved, which is in fact what happened with this.

There are various problems with the flying saucer hypothesis. One is the fact that people report humanoid occupants, although there are possible explanations for this. The entities could be manufactured or genetically engineered to look like us or convergent evolution might ensure that tool-using species are humanoid. Another is more serious: UFOs are visible. People report detecting them in various ways, such as on RADAR screens or more often visually. Even with our own relatively limited technology, we are able to make things almost invisible and undetectable on RADAR, but we are expected to believe that aliens can’t do this even though they can cross interstellar distances with ease. The alternative is that they want to be seen, but this is an unsustainable intermediate position because it doesn’t make sense for just a few craft to be seen occasionally. It can be confidently asserted that if they wanted to be invisible, they would be, so it then becomes necessary to explain why they don’t want to be. It’s fine as such if they don’t, but it would also mean the idea that they only associate with the “leaders” of the human race goes by the by. Also, the very idea that they would respect governmental power structures makes no sense. There’s no reason to suppose aliens would have government or that they would pay more attention to the people who happen to think they’re at the top of the pyramid. Of course, I’m personally convinced that they’re all anarchist, but there are other circumstances in which aliens might wish to subvert the hierarchy or just end up doing it anyway. Apart from anything else, they are after all aliens. They may not have the capacity to understand the nuances of human governmental systems, or they may arrive here not having learnt how it works. Or, they may wish to disrupt human society for nefarious purposes by inducing the panic world governments are supposèdly trying to avoid by keeping them secret. The nub is that if aliens were visiting us, they’d be able to hide from everyone, and if they didn’t hide from everyone they’d hide from no-one.

I do believe in UFOs of course. There very clearly are aerial objects which remain unidentified by any human observer. These are often things like Venus, birds, drones, weather balloons and so on, but I do also think there is another, very small set of other objects. These are secret military aircraft which happen to get spotted by people from time to time but whose existence isn’t openly admitted by the authorities. The one time I saw a UFO I couldn’t explain, that’s what it turned out to be, so maybe I’m biassed because of that.

I also believe that aliens would be benevolent for the reasons I set out under the Zoo Hypothesis.

Simply not believing that UFOs are alien spacecraft is not the same as believing we aren’t being visited or observed though. Maybe they are here. Maybe we are the aliens without knowing. I’m getting ahead of myself though. Here’s another similar idea to UFOs being alien spacecraft:

They’re Here But We Haven’t Noticed

This one is something of a mental health hazard because it very much stimulates paranoia, and again there are several versions of this. The closest one to the previous explanation is that there are indeed alien spacecraft, or perhaps nanoprobes, visiting or monitoring this planet but we can’t detect them, or haven’t done so. It does make sense that if they wanted to remain hidden, they would succeed in doing so, given their level of technology. One suggested means of eploring the Galaxy is to launch swarms of minute spacecraft in order to save energy and avoid collision with dust and other bodies between the stars simply by being smaller. It would also be relatively easy to secrete a reasonably large completely visible probe somewhere in the Solar System or in orbit around Earth without attracting much attention. Another somewhat disturbing further option exists. Right now, we can do 3-D printing and have some ability at genetic engineering. We aren’t that far off inventing a replicator, should that prove possible at all, bearing in mind that things often seem easier before they’ve been done. But for a technology far in advance of our own, it should be possible not only to produce a completely convincing living human, but even one whose memories are false and doesn’t even realise they’re the product of an alien machine. In other words, we could ourselves be aliens without even knowing. This kind of prospect is very similar to the kind of beliefs many children have and also has some resemblance to Capgras Syndrome. Whereas all of these things are possible, they are almost by definition non-scientific as they have no way of being falsified. Perfect camouflage is just that. No test can be performed to verify or refute that it happens. Therefore, whereas all of these things seem entirely feasible, they aren’t actually particularly meaningful as a simpler explanation for what we observe is that there are no alien spacecraft or “pod people”.

They’re Too Alien

Many answers to the Fermi Paradox seem quite anthropomorphic in one way or another. For instance, both the Zoo Hypothesis and the Dark Forest attribute perceived human-like behaviour, in opposite directions, to these unknown and possibly non-existent beings. But what if the reality is that aliens are in some way intelligent but also truly alien? What if they’re just fields of singing potatoes? They’re very intelligent, to be sure, but all of that cleverness is channelled into art so sophisticated and arcane that it can’t be grasped by humans, and also they sit there and do nothing else. They might send up a shoot or two with eyes on the end every now and again and look at the stars and planets in their night skies, but it doesn’t grab their interest. Of course, the singing spud scenario is borrowed from Grant and Naylor, but it’s one of many possibilities, some unimaginable and all unanticipated. We are one example of a tool-using species. Another one may be dolphins, and it doesn’t look like they’re going to develop our kind of technology at any point, not only because they live in the sea and don’t have anything like hands, but also because they’re just not interested, and that’s just on this planet and quite closely related to us. Or they could be a spacefaring species like some humans aspire to be but just have no concern about meeting any aliens or getting in touch with them. We might not even recognise each other as alive. For instance, what if they were a rarefied plasma drifting between the stars?

Different Or No Maths

I went into this one the other day here. Most of us humans don’t distinguish between subitising, which is the ability to judge how many items there are at a glance and which we are usually able to do about five, and the kind of activity which counts as arithmetic and mathematics. I won’t wade in here but there doesn’t seem to be any good reason why we would have evolved an aptitude to do mathematics given our lifestyle, or for that matter for any other species to do so given its niche, but we’ve done so anyway and this has somehow proven to be useful in rocket science and the like. Maybe it’s this which is missing from other intelligent life forms’ faculties, so they do fine building some kind of civilisation where everyone isn’t just a number, but they never leave their home world because they never develop anything able to do that.

Right, so this has turned out really long, so at this point I’m going to stop and publish. Part II in a bit, possibly tomorrow.

The Expanding Sphere Of Exploration

I am pessimistic about the future of the human race. The fact that we have come this far without dying out is a given of my existence, so it doesn’t follow that we will be resilient into the future. Maybe all we have been doing is running on luck. Perhaps out there in the Galaxy, life arises on hundreds of millions of planets, only to be wiped out by a gamma ray burst or series of impacts, and that hasn’t happened here, but why shouldn’t it? It so happens that there are reasons for this, but I’ll come to those later.

The other day, someone jokingly suggested that I believed ‘Star Trek’ was real. Whereas it would be nice to live in a post-scarcity society, I’m not actually specifically very keen on ‘Star Trek’ in the larger scheme of things and don’t find it at all believable, for reasons entirely other than the whole post-scarcity utopian space federation bit. My difficulty with suspending disbelief in ‘Star Trek’ is that it’s really what I’ve heard described as “mushy soft science fiction”, on the Mohs Scale Of Science Fiction Hardness, on which ‘Star Trek’ is apparently gypsum (and H2G2 is talc – not at all sure about that). I would actually swap those two. H2G2 is not very feasible at all of course, but for example, being initially a radio series it has plenty of non-humanoid aliens. ‘Star Trek’ TOS had more non-humanoid aliens in it than later series, and there’s an in-universe explanation for it which doesn’t really work, but that’s only one aspect. Others are faster than light travel (FTL) and gravity control. There are some advanced but feasible bits of tech in it too such as replicators, teleportation and androids.

Science fiction of a certain type basically has to have FTL, because if it hasn’t, events will be dominated by the difficulty everyone has in getting anywhere. This can be circumvented by making the story about the trip, setting events on a single planet or habitat or just not including space travel at all, but the sad thing is that as far as anyone knows, travelling faster than light is impossible in any meaningful way. There are jets of plasma shooting out of galaxies which seem to be travelling that fast but this is due to a foreshortening effect arising from the angle we see them at (I have to admit I’m not clear about what happens). Superluminal movement also happens due to the blurred nature of a wave function which means that when quantum tunnelling occurs a particle has a low but not zero probability of appearing on the far side of the barrier faster than it could have got there if it was moving at the speed of light, and if negative mass can exist, a warp drive is feasible. In fact, negative energy makes warp drives possible too, which is almost the same as nothing travelling faster than bad news. Douglas Adams again. Finally, the Universe expands faster than light, which is why space is black – light hasn’t had time to reach the observer over most of it, and may never do so.

It is of course feasible that we’ve just got hung up on our own version of physics and that there is another way of looking at these things which would make it possible to come up with a way of doing it, but there is no real reason to think this. This post, though, is not about what’s unfeasible, but about the prevalence of life, and possibly intelligent tool-using life or something that life has invented, in the Universe, or more specifically this galaxy.

The well-known Fermi Paradox is very simple to state: considering we live in such a vast Universe with unimaginably huge numbers of suitable stars for life and apparently also solar systems, where are all the aliens? Why don’t we constantly hear radio transmissions from them? Why can’t we see megastructures built around other stars? Why haven’t they visited us? A common conclusion to draw from this is that there just are no aliens, or at least no intelligent ones with spaceships and radios and stuff. It’s just us. There are a large number of other explanations offered, most of which have been heard many times, and new explanations are now emerging. One of these is the so-called “interdict scenario” offered by YouTuber and SF author John Michael Godier but based on an idea proposed by Martyn Fogg (I think) three dozen and a bit years ago where there was a chaotic belligerent phase early in Galactic history which has now settled down and civilisations in the Galaxy are now mature and welcome original thought, which arises best in species which haven’t been contacted yet. The Alpha Quadrant situation in ‘Star Trek’ is more like what was happening æons ago, perhaps even before Earth formed, and all of that’s now been sorted out. All of that diplomacy is extremely prehistoric and passée because it’s no longer necessary. Nowadays there are ancient protocols for first contact and the Prime Directive, and they’ve had time to get good at it.

The opposite to this is the Dark Forest scenario, 黑暗森林, suggested by the SF author Liu Cixin (刘慈欣) in his book of the same name, which I have yet to read. The details of the idea can be expressed through game theory, but rather than doing that it’s better to explain it via a metaphor. It can be summed up by the following quote:

The Universe is a dark forest. Every civilization is an armed hunter stalking through the trees like a ghost, gently pushing aside branches that block the path and trying to tread without sound. Even breathing is done with care. The hunter has to be careful, because everywhere in the forest are stealthy hunters like him. If he finds another life – another hunter, angel, or a demon, a delicate infant to tottering old man, a fairy or demigod – there’s only one thing he can do: open fire and eliminate them.

刘慈欣, ‘黑暗森林’

The situation does actually resemble that of terrestrial biomes quite closely, where many prey and predator species have evolved camouflage because those that didn’t either got picked off and killed or starved to death. If the laws of nature continue to operate with technologically advanced species in an interstellar environment, in a way it wouldn’t be surprising for them to be hiding away in this manner. In this scenario, humans are actually being quite reckless in that we make no attempt to disguise our presence and location, and consequently put ourselves at risk from alien attack.

I quote these two attempted solutions not so much to discuss them as to illustrate the contradictory ideas we have projected onto the Universe, which makes it even harder than the available data make it to work out what’s going on out there: the “real Galaxy” scenario. Another quite popular suggestion is that there’s just us, in various different ways. We could be the first of many, life could be really unlikely, it could be common but hardly ever becomes complex or our solar system might be unusual in some way which supports the development of our kind of life.

We will probably never even return to our natural satellite, let alone create space habitats or settle other planets. If we did, it would almost certainly make it very improbable that we were living before that time because of the vastness of the Universe and the number of places which could be settled or colonised, so any kind of space opera-style SF, no matter how carefully it respects scientific plausibility, is in the realm of fantasy if it includes human beings as a spacefaring species. But maybe, who knows?

We do have some limited information about how things are. There are only limited signs of this planet ever having hosted a technologically advanced civilisation, in the Eocene, whether that evolved here or elsewhere, so we can confidently assert that anyone who got here either trod amazingly careful or just didn’t come at all, perhaps because they never existed. Then again, maybe extraterrestrial civilisations aren’t interested in planets because they live in space arks or artificial colonies in space, possibly placed around stars we regard as hostile to life such as Rigel or the four-star Mizar system, which Earth astronomers never bother to look at in that way because of their apparent hostility for and implausibility as potential abodes for life’s evolution. It’s all unknowns. Nonetheless, I shall spin you a tale credible enough for me to entertain it briefly, at least for the purposes of this post.

In the early Universe, the Milky Way formed. Initially, its stars were mainly very large and short-lived and their planets were just balls of hydrogen and helium because heavier elements had yet to form in any quantity. During this period, metals (the astrophysical term for any heavier element) began to be forged in the cores of these stars and as they met their demise as supernovæ, they ejected these more massive atoms and the next generation of stars began to form with rocky planets and moons. Life arose or arrived on these bodies and over a period of æons, intelligent species evolved and began to develop technology. This took place in a kind of bell curve, with some appearing quite early because everything had gone “right” for them, and they found themselves apparently alone in the Universe because they were as of yet rare in the Cosmos. Nonetheless, some of them made their way into the Galaxy, explored it and settled on planets, perhaps making them more hospitable in the process or genetically modifying themselves to do so. Then the emergence of intelligent life reached its peak, around nine thousand million years ago, and many of them encountered each other. There was a long, indeterminate period of hostility and war, although it is difficult to conduct anything like a war between species living light years apart. This settled down after some time, perhaps millions of years, and galactic civilisation reached its mature phase. Systems were set up to share information and technology, and customs evolved to integrate newly-emerging species into the galactic social order. By the time Earth formed, over three thousand million years after the first interstellar civilisations arose, there were established and stable agreements not to interfere with primitive planets until they were ready. Yes, this is the interdict scenario. Very often in science fiction, the situation depicted is of a range of intelligent life forms who are of roughly the same stage of technological development as each other with a few who are so far advanced compared to the others that they’re like God. This seems unlikely because of the sheer age of the Galaxy. Civilisations might collapse and species go extinct of course, but even if this happens a lot, the period during which an interstellar culture could thrive might be very long indeed compared to current history. On the other hand, maybe technological progress reaches a plateau at some stage and the current phase of apparent rapid technological and scientific change is a brief “blip” between the more routine stages of the Palæolithic and an interstellar utopia. This confronts us with another paradox: that in fact we are the unusual ones and in a way the far future, if it happens, and the current state of most spacegoing civilisations in the Galaxy, actually have a lot in common with the Stone Age compared to what we have now. Having said all that, I haven’t fully thought through the implications.

Before I commit myself to this state of affairs, I want to describe another, very different one. It starts the same way as before, but instead of the early tail of the bell curve being in the distant past, it’s now. Humans are in fact unusually early as a technological species. When we go “out there”, we will find a sparsely-peopled Galaxy which does have other species capable of interstellar travel, but we’re all outliers and the glory days lie in the unimaginably distant future. Or alternatively, without anticipating the future, intelligent life is present but sparse in the Universe, so our nearest interstellar neighbours could be 576 light years away, and it has always been so and will continue to be like this in the future until all the stars go out. What then?

Humans have recently discovered that our very closest interstellar neighbour, Proxima Centauri, has a planet orbiting it with roughly the same mass as Earth’s, and in any case a maximum mass of less than three times ours, actually 2.77. Bear in mind that even that upper limit isn’t that much larger because if its density is the same, it gives it a diameter, with spurious accuracy, of 17 915 kilometres, only 40% larger, as would its gravity be – just slightly too high for comfortable habitation by humans. Its equilibrium temperature is only ten percent lower than Earth’s, which easily gives it a chance of having water oceans on its surface. We’ve kind of hit the jackpot first time, but incredibly, this isn’t big news for most people! However, this bizarre apathy isn’t the focus of my post. What is, is the fact that in a sphere around the Solar System with a radius of only 4.3 light years, there may be two habitable planets. There’s definitely one of course. If that “sample” were to be extrapolated by doubling the radius of the sphere to 8.6 light years, almost the distance to Sirius, it would octuple the volume and “statistics” would suggest eight habitable planets within that radius, which is clearly not so. There aren’t even eight star systems, including the Sun, within that sphere, and as could be expected three of the stars are red dwarfs, which are easier to detect so nearby, but more can be supposed elsewhere. It’s been said previously that red dwarfs appear to be surprisingly good candidates for habitable planets, so it’s not beyond all reason to assert that there might be some there, but they’re not Sun-like stars.

With a further increase of radius, the sphere could be expected to become a more accurate sample of the space in this region of the Galaxy. For argument’s sake, I’m going to assert the idea that there are five more habitable planets within six dozen light years, with the possibility that there might be more than one in some systems. For instance, if our own practically double planet system is in any way typical, and it probably isn’t, there might be another whose larger component is at the upper luimit of habitability and whose smaller one is at the lower, or perhaps a system with two habitable worlds, one very hot and one very cold. The TRAPPIST-1 system contains seven Earth-sized planets within a habitable zone, for example. Nonetheless, they could be expected to level out at less than two on average per system which contains any. Six such planets in a 72-light year radius sphere will have a mean distance of almost sixty-four light years from each other. However, at that rate the sphere of exploration would only need to be about three light years further for another to be found. Hence exploring space in this way, whether by going out there, sending probes or astronomical observation, would be exponentially more successful. And this ignores the idea of setting up further facilities on the outlying planets, or near the edges of explored space, increasing the chances of finding them more quickly and even further out.

John von Neumann, the mathematician, suggested that interstellar space could be explored relatively quickly and efficiently by releasing a space probe which, when it reached the target system, would build a copy or two of itself which would then be despatched on to more distant systems. Given that there are four hundred thousand million stars in the Galaxy, this would require around forty generations of probes, which is not hugely impractical-sounding, but the problem is that releasing such craft into the interstellar environment runs the risk of mutation and evolution into a swarm of “grey goo”-style craft attempting to convert all the suitable material in the Milky Way into copies of themselves. It would also still take a minimum of fifty thousand years for such a programme to cover the Galaxy, and a minimum of a further fifty thousand for all the data to be received. I will be returning to von Neumann’s devices in future, as they seem to have quite profound significance.

Combining the doubling of probes with the exponential growth of likely planets as the distance increases means that there is no impediment to a long period of such growth. Even if it takes five centuries to find the first five closest worlds, the sixth is likely to be found within five years of the fifth, assuming velocity is not a limit. This also means that the probability of finding a new one per year would have grown similarly in the intervening time. The longest wait could be expected at the start of this period. This assumes , though, a relatively homogenous Universe of infinite extent with regular distribution of potential homes for humanity. In the long term, this is unlikely to be so.

This is where the two constrasting scenarios of sparse relatively young and isolated civilisations and common mature confederated ones come into play. Deciding to assume that the average distance between spacefaring civilsation home worlds is 576 light years, which is exactly eight times six dozen, gives a sphere of influence (not really a sphere of course as there would be gaps) averaging out at 288 light years radius. This assumes also that the environmental requirements of different species are identical, raising the possibility of competition. This takes on a different significance when one considers that what may in fact have happened, for all we know, is that the biological entities who originally designed von Neumann machines may be long gone by now, and what we would in fact find is a galaxy dominated by machines of that kind, which would be a lot less fussy than animals about their requirements. Depending on the age and rate of exploration of our neighbours, we would of course be increasingly likely to meet. It’s been claimed that the nature of First Contact may be less important than the fact it happens at all, because of the impact of the realisation that we’re not alone in the Universe, but it would seem that if the Dark Forest explanation is true, that wouldn’t be the case as the chances are then that there would be a swift attempt at mutual annihilation, and that’s more significant than just discovering aliens. However, though a wonderful source of drama, the Dark Forest explanation is unlikely. This planet has had very obvious biosignatures for hundreds of millions of years or longer, for instance as the spectrographically detectable free oxygen in the atmosphere, and nothing has happened in that time which looks like an alien attack. Why not root out the possibility of intelligent life early rather than, say, wait for the industrial revolution? The increase in carbon dioxide since the Industrial Revolution is a technosignature, though possibly an ambiguous one. CFCs and the depletion of the ozone layer, however, are pretty much certain technosignatures because of the nature of fluorine and chlorine, which can only be handled and produced industrially in that way. We’ve been advertising our presence to a possibly empty Universe for a very long time. Incidentally, the transmission of routine radio signals is not an easily detectable sign because it isn’t as persistent as many people think it is. In fact, it disappears into the noise before it even gets to Proxima. I have to confess that I don’t know how far the Arecibo telescope message has reached or will reach.

I’m going to call the two scenarios I’ve already mentioned “Interdict” and “Early Tail”, and introduce a third, “Absent Aliens”, which is where there’s no other intelligent life in the Universe. In Interdict, the situation would probably arise where soon after First Contact, uplift would occur. I may be using this word unusually. By “uplift”, I mean the idea that advanced aliens will help us improve the level of technology and scientific information available to us, perhaps in Interdict in exchange for our original thinking and cultural artifacts. This has a kind of religious, cargo cult flavour to it, but in practical terms as far as discovery of new worlds is concerned, this could simply involve humanity being given a catalogue of every such world available to and suitable for us throughout the Galaxy. If this happens, a gradually increasing bubble of knowledge would just suddenly expand in a leap, and this would include other areas of knowledge.

In Early Tail, assuming friendly relations between us and aliens, and there are reasons to suppose that would be so, the bubble expands up until First Contact, after which information about suitable planets in other regions of space known to the aliens is shared. These aliens may or may not have similar requirements to our own, such as temperature, pressure, the presence of oxygen in the atmosphere, particular levels of gravity and so forth, and they may have incidentally discovered planets suitable for us but not for them. The situation could be intermediate or not. For instance, chlorine-breathing aliens who find oxygen poisonous are not in competition with us for habitats, although they may be for mineral resources or solar power, but extremophile-type aliens who thrive in conditions like those of Antarctica could have overlaps with us, and this could influence their attitude towards both sharing information and bothering to find out about it in the first place. I presume nobody with any influence is currently proposing the detection of planets with free chlorine in their atmospheres, so would we know about them in our own sphere of exploration by the time First Contact occurred or not? We might come across them accidentally though, and if we did, that would probably be a biosignature, though of very different life.

A simple Early Tail scenario is encountering aliens whose homeworld is 576 light years away with similar biology to our own, though of course probably not humanoid. If it takes five centuries to reach seventy-two light years from here during which five suitable worlds are visited and perhaps settled, and the aliens have explored at the same rate, we could expect to meet them when both spheres have a radius of 288 light years, which is four times that distance, and could therefore be expected to occur two millennia from now, by which time almost four hundred worlds would have been found by each. Assuming early friendly information-sharing, it involves an almost instant doubling of both species’ knowledge at that point. The rate of alien contact would also ramp up fast in the same way as the discovery of planets from this point because of the increase in explored volume. The idea of the average distance to intelligent aliens with interstellar civilisations being that far commits us to an estimate of the likelihood of a habitable planet having such life on it being around one in three thousand. Taking the window of habitability on our own planet as typical, i.e. around 1 500 million years, this would mean that the average time such a civilisation will exist, including the evolution of various species not directly connected to each other, would be around half a million years. However, this may not be how things really proceed, either here or elsewhere. Maybe there is instead a threshold in evolution after which intelligent life is a constant feature of the biosphere. There are a number of examples of species with somewhat similar intelligence to our own on this planet, including elephants, parrots, cetaceans, corvids, parrots and other simians. Maybe from now on, there will always be intelligent life here, and if this is so we can expect something like two-thirds of the suitable planets we encounter to have intelligent life on them. Using the density of habitability I’ve suggested, it could mean that the second world we come across will have intelligent life on it, or even the first.

Alternatively, intelligence and tool use could turn out to be an evolutionary dead end. Contrasting the polar opposites of releasing sheer clouds of young, like a coral, oyster, fish and to a lesser extent turtle, and not bothering with parental care, and having one or a very small number of young at a time which need extensive parental care and a learning period before being able to cope on their own, the second of these means that orphans tend not to thrive, it’s a long time before the next generation and we are unlikely to do much more than produce a few children. If an organism doesn’t need to mate, one individual in an environment empty of peers is likely to lead to a thriving population after very few generations, particularly if parental care is not required. Brains are also very resource-hungry. The human brain can account for up to 87% of resting basal metabolic rate. All this means that humans are vulnerable to major disasters and food shortages to a far greater extent than many other species with different reproductive and survival strategies, and it may be that other intelligent, technology using species have the same problem, meaning that they may not thrive for long. There’s also the evil twin of the Gaia Hypothesis, Peter Ward’s Medea Hypothesis. This is the idea that complex life tends to be fragile and vulnerable to extinction because of the activity of microörganisms, meaning that the more stable state of a biosphere is what was seen over most of Earth history, namely a load of microbes without much visible evidence of anything much going on and not even anything as advanced as an amœba. Medea in Greek mythology, found in ‘Jason And The Argonauts’, is the archetypal bad mother in the same way as Gaia is the archetypal good one, who murders her children. There have been a number of occasions in addition to the well-known mass extinctions of the Phanerozoic (the time since large hard-shelled animals evolved) which have almost destroyed all life on Earth: the oxygen catastrophe, snowball Earth, methane poisoning and a number of times hydrogen sulphide has been released in large quantities and nearly killed everything. Right now, anoxic zones are developing in the oceans which have in the geological record been associated with mass extinctions, and many organisms remove carbon from the atmosphere and deposit it in rocks such as chalk and fossil fuels, thereby making it unavailable as biomasse for a very long time. Therefore it could be that animals and complex plants are not a long-term prospect, and in fact they’re established not to be by the known course of our planet’s story. Hence intelligent life forms and even complex life forms of any kind might be rare even if microörganisms are not. Ward believes that the main immediate cause of mass extinctions is the release of hydrogen sulphide into the atmosphere by purple sulphur bacteria, which destroys the ozone layer and poisons ærobic life, caused by rapid global warming such as flood basalts releasing carbon dioxide, but also of course potentially by our own activities. If it’s common for this to happen when technological cultures become industrial, it could limit the length of civilisations dramatically, and it may be why we will never settle on other worlds or create large space habitats.

Assuming we survive, in this scenario the expanding sphere of exploration would simply proceed exponentially without any catalysts. However, we might not be finding anything interesting because although there could turn out to be plenty of planets like Earth, even with life on them, most of them would only ever have had simple, microbial life and many more would have permanently devastated environments, similarly with simple life but which once held complex life before the advent of intelligent life forms who managed to wipe almost everything out. Then there would be the occasional intelligent species which was still around but didn’t have long to go, probably too sparsely distributed for us ever to find any. And we are probably one of them.

Further limits emerge when expansion gets beyond about 1 500 light years. This is half the thickness of our spur of the local galactic arm. Beyond us are rifts in the Galaxy largely empty of stars or planets, and the neat sphere I’m imagining will no longer be spherical. A second factor may also come into play here. There may be a ring-shaped zone of habitable systems concentric with the galactic core. Stars near the centre of the Galaxy are very densely packed, but in any case, dense or not, not capable of supporting life on any planets they might have. They’re so close together that they’re likely to disrupt planetary orbits and the high level of radiation from the central black hole is likely to kill everything on a planet. Our galaxy is a barred spiral. This roughly means it has two arms projecting straight out of the centre before the spiral arms begin. The situation in the bars is about as hostile to life as the nucleus is. Further out, where the arms begin, heavier elements are quite common and consequently rocky planets likely to form, but also many gas giants, possibly so many of them that they will tend to fall towards their suns and become “Hot Jupiters”, which disrupt the orbits of the smaller, more hospitable, rocky planets. Also, there would be more cometary impacts because the stars are closer together and more likely to disrupt the orbits of the comets which orbit in a cloud around star systems far out. In addition, supernovæ are more likely closer to the planet than is safe, wiping out life in another way. Further out, stars are sparser and there are fewer heavy elements, meaning that planets would be simple gas giants consisting of hydrogen and helium but not much more than that. Hence the best distance in this Galaxy is likely to be between 25 000 and 33 000 light years from the centre. We are 27 000 light years out. It’s also fairly dangerous to be deep in a spiral arm – apparently we’re near the edge of one. This is because there are many blue supergiants there, which tend to go supernova after only a few million years.

Therefore what we’d probably find is that our “sphere” of exploration would cease to be one once it got beyond about 1 500 light years around the orbit of the Sun, two thousand light years hubward and five thousand towards the edge. However, if we’re on the edge of an arm, as we explored inward from that there would initially be a growth in the number of interesting worlds followed by a region where life had been obliterated given that it existed near the surface of the body concerned, but not necessarily if it was in a subsurface ocean, which judging by our own solar system can be expected to be very common, and rogue planets which have escaped from their suns which nonetheless have a source of heat in some way would also be immune from these risk factors. Hubward, that is, in the direction of Sagittarius from here, we could expect to find solar systems with more planets than ours but also more Hot Jupiters and with more frequent mass extinctions caused by comet bombardments until it became unfeasible for life to develop very far, assuming it does anyway. Towards the other edge of the Galaxy, which I presume is in the direction of Gemini, there would be more hospitable worlds more likely to harbour complex life forms but with less abundant heavy elements, so for example our own reliance on iodine to produce thyroid hormones would have no parallel. Biochemistry would become simpler with fewer trace elements, if possible.

However, of course a lot of this is guesswork. The scenarios I’ve considered here are that complex life is rare, the Dark Forest explanation of the Fermi Paradox, the idea that we are early in the history of intelligent life in the Galaxy, that complex life is unstable and short-lived, and that intelligent life is widespread and has reached a stable and peaceful maturity. It’s hard to extend this beyond mere speculation, and of course in the end we just don’t know what’s going on out there. We also have a tendency as a species to project out imagination onto the sky, and should be wary of that if we want to adopt a rational approach towards the prospect of intelligent life in the Galaxy. There are lots of fairly obvious things I haven’t considered, such as the idea that biological life is replaced by robots, that aliens and humans might prefer orbiting space stations to planets, or that there’s loads of intelligent life but it spends all its time on the local internet, but this is a fair sample of the ways things might go if we ever get our act together enough to go “out there”.