Borges and Characters

But I think, perhaps, that the real reason he never wrote a novel was that the form is largely dependent on character, and Borges had no real interest in, or facility for, the creation of psychologically vivid people. (Try relating Leopold Bloom orally in five minutes, or Mrs. Dalloway, or Anna Karenina. Their greatness as characters arises out of their irreducibility to the facts about themselves.) He wasn't much for fleshing out, and he was not the kind of writer whose characters ever had a chance of "taking over" from their creator.

- From the New Yorker


More here on the underrated optionality of character in fiction.

How Close Are We to Becoming a Kardashev II Civilization?

Kardashev II civilizations have the power capabilities of an entire star. One way to do this would be to capture the star's energy with a Dyson sphere (below).


Futurists and science fiction types (myself included) often over-simplistically extrapolate current, very strange trends (in terms of the rest of history and nature), especially exponential ones. Despite that, people are looking for Dyson spheres for real as part of SETI. I think this program carries so many assumptions that it's doomed; but let's have some fun and say Dyson spheres are for galactic wusses that don't have the stones to just generate the power themselves. If we humans are eventually going to produce enough power to match our own star, how close are we? Is this something that should be discussed during the next election cycle?

Take a guess. Here are the numbers: the current energy output of humans is about 5x10^20 J per year (since this is energy over time, we're really talking about power). The Sun's output is 1.2x10^34 J per year. So how close are we? A factor of 24 trillion, that's how close.


Let's assume, even more stupidly, that our energy curve will continue to rise the way it has in the twentieth century (see above), despite the fact that the vast amount of that area under the energy-time curve (again, power) came from spending stored chemical potential energy in fossil fuels. The curve has gone up 1x10^14 J about every 15 years - arithmetically, not geometrically. At this rate of increase, the sun will have burned out long before we ever match it. (If you want to be a smartass, you could say that this means that we will eventually match the sun's power because the sun's output will drop drastically. But even then the constraint which determines this is the sun, not how fast our energy output grows.)

Another way of looking at it: if you wanted to match the sun's power by burning fossil fuels, then using the energy density of oil, you would have to burn an amount of oil equal to the mass of the Earth, 50 times per second.

What is this, XKCD?

You're saying, "Fossil fuels? Of course you idiot, you can't get to the Kardashev big leagues powering your civilization on combustion engines!" Fine, let's make an Earth out of antimatter, and gradually crash pieces of it into this Earth. You could put out as much as the sun for about a hundred million years, by shooting pieces of the anti-Earth at us at a rate of a million tons per second. (I guess you hold the Earth together with duct tape to keep it from flying apart during all these shenanigans.) Assuming you don't start with the part of the Earth where you're sitting it would probably look cool, but even so I bet you'll quickly be getting some neat-o cancers from all the high-energy photons this produces, and maybe even just diffuse axonal injury knocking you unconscious in minutes. Incidentally my suggestion is to start with Belgium.

Above: Belgium, at left.

There will still be people objecting, i.e. the Ray Kurzweils of the world, that problem-solving abilities (AI) will grow exponentially, and therefore the energy-producing capacity will follow. Fine. The question for them is what is going to power these other exponential trends, at much more mundane time horizons? (Like the singularity that's apparently scheduled for seven decades from now.) If the answer is "AIs will have god-like intelligence and they'll be able to do it and we can't understand", then why shouldn't we also believe doomsday prophets like Harold Camping who say their gods are coming, and make their claim with exactly the same amount of verifiability and comprehendibility? If you think Kurzweil makes sense, you should also read about the economist Julian Simon's commodities bets, because you should agree with him - although I find that singulatarians somehow find reasons to dislike over-optimistic economists, probably mostly just out of mood afiliation and status considerations.

Final answer: we are not going to become a Kardashev II civilization any time soon, and no one really knows how to get there or what this means, because the definition necessarily involves processes we don't understand. But I'm still fine with dropping large amounts of antimatter on Belgium.

ADDENDUM: This is from Wikipedia about the sun's power generation and for some reason I find this shocking.

The power production by fusion in the core varies with distance from the solar center. At the center of the Sun, theoretical models estimate it to be approximately 276.5 watts/m3,[54] a power production density that more nearly approximates reptile metabolism than a thermonuclear bomb.[b] Peak power production in the Sun has been compared to the volumetric heats generated in an active compost heap. The tremendous power output of the Sun is not due to its high power per volume, but instead due to its large size.

Putting it in socioeconomic terms, the sun is like China - the per capita income is actually not impressive but it's huge, so the multiplier is big.

For The Over-Optimistic

Brief online debate between David Brin and Aubrey de Grey here. Brin points out that the low-hanging fruit for life-extension have already been picked, and that any life extension on the order of decades (not to mention indefinite extension) will require "thorough" intracellular nanotechnology. Agreed. There is always a component in every make of car that fails first, and even if you keep replacing components, eventually you'll be putting new parts in every day. This is why people don't keep repairing their cars indefinitely! What's more, a car is not a person. Your transmission is not you. Your brain is you. And we don't know how to replace that practically, and we still don't understand consciousness and self even at a basic philosophical level.

Living a long time is emphatically a worthy goal but we will not have this technology in the next few centuries.

RE No Country For Old Men: Chigurh's Brain

If you haven't seen No Country For Old Men, what's wrong with you.

The fascinating thing about this movie for me was the behavior of Anton Chigurh (played by Javier Bardem) relative to other characters. Chigurh seems to be the only guy in this movie with frontal lobes, particularly in terms of his ability to model the other characters' behavior, while they're utterly at sea about his next action - like a human playing with a dog. The difference in the use of language is particularly striking: the rural hayseeds he victimized throughout the movie are uncertain, approval-seeking, making simple, naively truthful declarations. Chigurh only speaks to cause an effect - his words are noises that move things - and the effect is sometimes a certain behavior from one of the hayseeds, and sometimes to amuse himself. If he says something true, this is incidental.

What's so fascinating about this? Because although Chigurh might be the only person in the movie who has free will (as opposed to reflex and instinct), he seems not to believe in free will: he has placed his behavior, or believes it is inevitably, under the control of rules and fate. In this scene, he is (we assume) determining whether he'll kill a gas station attendant based on the flip of a coin:


The tension in this scene is among the best in the history of film. Do note the unplanned choking on the peanuts. There was no rule, no fate there, and it hurt him.

Later in the movie, when Chigurh is about to kill Woody Harrelson's character, he asks if "If the rule you followed brought you to this, of what use was the rule?" The ending is interesting in that Chigurh gets into a bloody, near-fatal car accident - accident.

As I Lay Dying's Tim Lambesis on House Arrest, "Focused on Study"

Story is here.

Consuming Random Elements and Werewolves

I'm kind of jealous of the first half of the twentieth century. It was a time when you could just feed frogs rubidium and write down what happened. I once argued that based on its rarity, ruthenium was actually a better currency standard than gold; gold is (or was) a standard by historical accident of having a high redox potential, therefore being the only metal found in nature in its non-oxidized form, plus monkeys like shiny things. Okay, forget the common isotopes of elements; what happens when you start feeding, so heavy water to living things? Not much, actually. No eye lasers, no phasing through walls, you don't even turn into a werewolf. It doesn't even taste any different (according to Harold Urey)


Nope. Not even close.

So what do you have to do to poison yourself with heavy water? To show the initial effects, you'd have to drink about a quarter of your water weight. Those initial effects in mammals are sterility - D2O in high enough concentrations is toxic to rapidly dividing cells, just like radiation or free-radical generating chemical species; this is a result of the altered kinetics when free protons begin to be replaced with slightly-more-than-twice as massive deterium nuclei. Consequently as the concentration increases, the damage begins to effect other high-turnover tissues next, like the GI tract and after that, presumably the central nervous system. Mammals given only heavy water die after a week. It turns out a disgruntled employee at a Canadian nuclear power plant spiked the office water cooler with D2O back in 1990, but it wasn't enough to replace any significant water weight as mentioned above, and no one was injured.

One interesting (but simplistic) idea was that in slowing the reaction kinetics of an organism's biochemistry, you could slow the organism's aging. And indeed it was shown that Drosophila given D2O did live longer. No telling what's going on to their gametes or nervous systems, or what would go on in a longer-lived more neurologically complex organism!

The question of why our ancestors made some very basic chemical commitments (nerves based on sodium, potassium and calcium flux, for example) is interesting but ultimately not useful, very likely having to do with the happenstance of what was available and soluble at the Earth's wet crust. Lithium is similar enough to sodium that it can fool certain sodium channels in the central nervous system and decrease the rate or amplitude of mood swings in bipolar people, but that's a coincidence.

By the way, the werewolf formulas are pretty disappointing. There was one where you can use a mixture of nightshade and children's blood and smear it on your skin during a full moon but it didn't work. Maybe you can't use your own blood like I did (but I was ten, so it should count.) Another way is to drink water out of a wolf paw print in the Harz Mountains in Germany. I'll have to import the wolves since they're not extirpated in Germany.

Into the Void (Orig Black Sabbath, covered by Soundgarden feat. Chief Seattle, Satanoscillatemymetallicsonatas, 1992)

I never knew this existed until five minutes ago. I always thought this song seemed written by Soundgarden. Chief Seattle can't rhyme for sh*t.

The Big Rip Is Already Happening

From this interesting piece at Less Wrong, which shows we're losing about one galaxy per year due to the accelerating expansion of spacetime - also, associated arguments on why we must maximize the chances for successful colonization.

Late 1800s Political Science Fiction

Cross-posted to the Late Enlightenment.

Here's an interesting old science fiction book: Better Days: Or, a Millionaire of To-morrow, by Thomas and Anna Fitch. This should rank with Bellamy's Looking Backward. Set in the authors' near future of the 1890s, in it a wealthy industrialist develops bombs powerful enough to level cities, that can be launched accurately from zeppelins or boats. To be clear, this is a utopian work - although it involves an early prediction of the nuclear age, the authors assume it would necessitate a global detente. The authors correctly understood some of the political ramifications: that these weapons would have to be regarded in a special category and their manufacture restricted by international agreement so that they did not proliferate; and so he also predicts a version of the League of Nations. What he failed to predict was how this would be accomplished; by a cartel of countries who openly have such weapons, and a secondary cartel of those who everyone knows has them but don't openly declare them. The book features various heads of state realizing and announcing that they must cease prosecuting wars and allow all their territories to return to home rule to avoid their own capitals being destroyed by other states or even small groups of revolutionaries who make the explosive agent ("potentite"). If it's that easy, it would seem his international non-proliferation police wouldn't be able to do their jobs. U-235 is harder to make than potentite and we still seem to be nervous about Iran. We should be glad it was nuclear weapons and not potentite! (Or microwaved sand as Nick Bostrom speculated.)


Above: Coronado is the north-pointing peninsula at top, and the islands are to the south.

Of local San Diego interest: the initial tests for the various heads of state are carried out from Coronado, long before it was selected as a naval airfield. Unfortunately the Coronado Islands are destroyed in the demonstration. (Although last time I looked out the window of Hillcrest Hospital I could see them just fine; so for this and other reasons, this is alternate history now I guess.) The authors were possibly more interesting than the book; the husband seems himself like a character made up for historical fiction. Thomas Fitch was an attorney and politician who served in the legislatures of no less than four of the states and territories of the time (California, Nevada, Utah and Arizona), which explains why his knowledge of the Western U.S. of the time was more than the caricature we often see from contemporary writers on the East Coast. In his legal career he also represented Brigham Young and Wyatt Earp. He proofread Mark Twain's manuscripts and hung out with Leland Stanford. Finally and most significantly, as an orator, he was credited with keeping California in the Union. Even if you can't forgive his book's inconsistencies and failed predictions, I think he did okay.

And This Wouldn't Even Be the Singularity

From the Berkeley Robotics Department.
Economist Tyler Cowen asks "What is the political equilibrium when insect sized drone assassins are available?" All answers are unpleasant. This isn't even the Singularity, just a seemingly very likely possibility as mobile electronics continue to get smaller. They don't even have to be autonomous.

The smaller that automation gets, the more potential for disruption. We vastly underestimate the disruption from small autonomous flying robots. You'll move (or run) if you're walking somewhere and see bees. And bees are stupid and mostly want to ignore us, and can't even kill us.

The Fermi Paradox Thickens: More on Colonization Times for Von Neumann Probes

In a previous post I discussed the possibilities of replicators being aided in their diffusion between star systems by close passes; I also pointed to an interesting paper by Forgan et al looking at projected travel times of interstellar probes, based on powered vs. gravity-assist travel. A new paper (on which Forgan is the senior author) looks again at this problem using a Monte Carlo simulation approach, and gets an interesting but as always frustrating answer.

First, the paper would be valuable if all it contained was the excellent review of prior work done on this NP-hard version of the traveling salesman problem. (You think planning your road trip taxes a server?) In particular, they point to a prior paper arguing that von Neumann probe expansions could be slowed or stopped by mutant probes where a predator-prey dynamic evolves in the population and the probes hunt themselves to extinction. I had previously written about self-replicating probes becoming cancerous (a statistically more likely outcome) and turning to expansion above any other mission they previously had; but this only makes the Fermi Paradox more vexing rather than solving it.

Their approach was to simulate the galaxy as having 1 star per cubic parsec (so no local "backwaters"), with self-replicating probes moving at approximately the speed of Voyager I, 1000 m/s. They then compared replicating and non-replicating probes; not surprisingly, self-replicators were much much faster, exploring 100% of a box of 100,000 stars in at most 30 million years. In the replicator condition, the number of probes is no longer the constraint, and contact can occur in (possibly massive) parallel rather than serially. Of note: the authors also include a requirement for communication of which stars have already been explored, although if we assume a robustly replicating probe, this is unnecessary. ("Robust" means that the time and ability to replicate enough probes to successfully reach the neighboring stars are small relative to travel time.)

The authors correctly note that this short time frame makes the Fermi Paradox more vexing. So the alternatives with respect to self-replicating probes are:

1. They're here and we haven't found or noticed them yet.

2. They're not here, because
2a. Replicating probes are not possible or not effective (they can't be made at all, or they mutate)
2b. intelligence capable and willing to build such probes appears more rarely than once every 30 million years in a volume of 100,000 stars (they choose not to, or they don't evolve in the first place, or they wipe themselves out before they create them)

2a seems unlikely because we already know that replicators can develop through natural selection. This leaves us with 1 and 2b. It is certain that we have only the barest knowledge of the rest of our solar system, and gravity wells are expensive to get out of. My prediction is that we'll find evidence of such probes on low gravity bodies (asteroids, comets, small moons) as we continue to explore, but that once we find something strange, it will take time for us to understand what we're looking at.

Hat tip to Ben Weaver.

Good Libertarian Attacks on Rand

Cross posted to the Late Enlightenment.

Recently I ran across David Brin (a libertarian) and his writings on Ayn Rand. These should have their own special genre; one which deserves our attention. 1984 was Orwell's answer to what he saw as the developing problems with socialism, and (as an understatement) it is an important work.

Before giving you the sharper points of another writer's attacks, what is good about Rand? What do people get out of it?

- The power of capitalism to eliminate human suffering.
- The power of the individual; it's not surprising that young people establishing their own identities are the ones to whom this most appeals, and (I would argue) it's important that young people have things that reinforce their confidence in themselves and their goals and values.

The piece in question is here. The most interesting argument he makes is that (in his view) Rand is clearly influenced by Marx in terms of her teleological thinking. He misses a chance to mention her infamous standing-on-one-foot answer, which was a ripoff of Rabbi Hillel. She borrowed at least once, either (most charitably) unaware that she was doing so, or assuming that her audience would not be familiar with these sources. (Which itself says something else about her.)

A point worth disagreeing with, not just here but with other writers, is that it's not a valid criticism to say that her novels lay out a plan for bringing Rand's values to the world. Not because the world in Atlas Shrugged is a great one, but because the novels don't claim to be a blueprint for what the world should look like and the actions to take to get there, even with a 70-page monologue. (I'm unfamiliar with her having made this claim in non-fiction. If you're aware of any such claims, please point me to the evidence and I'll change my position.) Compare to Marx, who in a non-fiction manifesto, laid out a plan for the dictatorship of the proletariat, which Lenin followed fairly closely.

(Another article that Brin links to makes the argument the Atlas Shrugged is part of trilogy. Interesting non-fiction plot twist in that one.)

Other weaknesses that have always appeared to me likely because of my background: a lack of familiarity with evolution and in one case a distrust of how it could have produced an intelligent animal; a strange proclivity to imply heritable positions in her characters (all while decrying decadent monarchies elsewhere); and implicit assumptions about gender roles including disparaging comments about possibly gay characters. To the last point, defenders might say "But this was the 1950s; you can't fault someone for being a product of their times," to which an appropriate response is "But this is someone who was claiming the absolute, correct and final version of morality; if she missed something, that makes it irrelevant whether or not the ambient culture produced those blind spots." When you claim to have produced the final answers, rather than improving the process to get the answers, these are the kinds of problems you're open to. (Defenders might also say that homosexuality is morally wrong, and then the discussion devolves to a more profound level about the origins of morality. The kind of people who take this position will have a hard time showing themselves to be on the side of reason and not irrational authoritarianism here.)

A final problem that Brin mentions is the inverse state worship that afflicts objectivists and libertarians, but this is not unique to Brin's critique or to Rand. Suffice it to say the state is not the only institution ever conceived that can make humans suffer.

Crysknife Show in Oakland, August 9 2013

They're playing Oaktown 9 August 2013 at the Grand Lake Coffeehouse.

Great Piece on the "Literature of Ideas"

Here is an excellent article from World SF on "The Persistent Neoteny of Science Fiction". In it Athena Andreadis points out - even-handedly - that defenders of "literature of ideas" are often really just bad or lazy fiction writers. On this blog I have often defended stories of ideas from literary purists from elsewhere on the literary spectrum (in particular, in reviews of Mieville's Embassytown), but Andreadis's point is an excellent one. Stories that work based on their ideas can afford to de-emphasize other aspects of story-telling, or dispense with some of the elements altogether; but this claim is very different than saying that these elements should be inferior and added only with the ham-handedness that comes with reluctantly obeying a form. ("Well it's fiction. We need characters I guess.")

Her central argument: "...SF/F suffers from a peculiar affliction: persistent neoteny, aka superannuated childishness. Most SF/F reads like stuff written by and for teenagers – even works that are ostensibly directed towards full-fledged adults." And the even-handedness: "Now before the predictable shrieks of "Elitist!" erupt, let me clarify something. Adult is not a synonym for opaque, inaccessible or precious. The best SF is in many ways entirely middlebrow, as limpid and flowing as spring water while it still explores interesting ideas and radiates sense of wonder without showing off about either attribute."

Do read the whole thing, but the introduction alone is applause-worthy:

When Margaret Atwood stated that she does not write science fiction (SF) but speculative literature, many SF denizens reacted with what can only be called tantrums, even though Atwood defined what she means by SF. Her definition reflects a wide-ranging writer’s wish not to be pigeonholed and herded into tight enclosures inhabited by fundies and, granted, is narrower than is common: it includes what I call Leaden Era-style SF that sacrifices complex narratives and characters to gizmology and Big Ideas.

By defining SF in this fashion, Atwood made an important point: Big Ideas are the refuge of the lazy and untalented; works that purport to be about Big Ideas are invariably a tiny step above tracts. Now before anyone starts bruising my brain with encomia of Huxley, Asimov, Stephenson or Stross, let’s parse the meaning of “a story of ideas”. Like the anthropic principle, the term has a weak and a strong version. And as with the anthropic principle, the weak version is a tautology whereas the strong version is an article of, well, religious faith.

The weak version is a tautology for the simplest of reasons: all stories are stories of ideas. Even terminally dumb, stale Hollywood movies are stories of ideas. Over there, if the filmmakers don’t bother with decent worldbuilding, dialogue or characters, the film is called high concept (high as in tinny). Other disciplines call this approach a gimmick.

The strong version is similar to supremacist religious faiths, because it turns what discerning judgment and common sense classify as deficiencies to desirable attributes (Orwell would recognize this syndrome instantly). Can’t manage a coherent plot, convincing characters, original or believable worlds, well-turned sentences? Such cheap tricks are for heretics who read books written in pagan tongues! Acolytes of the True Faith… write Novels of Ideas!

New Carcass, Captive Bolt Pistol

Not embeddable, here it is. Mostly in the vein of less imaginative Heartwork, although the solo work at 2:13 redeems the song.

Monster on Sunday, You (orig. Bad Religion, No Control, 1989)

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Zombie Movies Are Stupid

I don't get zombie movies. At all. They are movies about running away from hostile retarded people who are hard to kill and (an important qualifier) whose retardation is infectious. Oh, that's not what they're about? Fine. Tell me where that's wrong. (So far, no one has been able to. They just get mad.)

Of course, you're free to NOT think zombie movies are stupid. Of course that means you're stupid too.

Granted, some of the kill scenes are kind of funny but even those get boring after a minute (okay, okay I admit this whole sequence still makes me laugh every time; I think it's all the screaming). What's more, I just can't suspend disbelief to the degree needed to not think these movies are stupid. For even 2 seconds. Why not?

- you don't have to be a scientist to know that viruses do not spread and take effect that fast.
- they don't somehow make matter supernatural (i.e. give super-speed or not need to breathe - yes, from World War Z - or somehow make muscles keep moving even after the nerves that control them are broken)
- how is it that with fast zombies, every aspect of their physiology is enhanced (senses, speed, strength, resistance to damage) except their brain? Maybe there should be a movie with zombies that get smarter, but more easily winded and over-sensitive. That would seriously not be any more stupid.


If movie-makers want to explain their zombies, they should just say "because Hell is full"; that's more honest.

So in keeping with the defying-all-natural-law aspect of zombies, I want to see a movie with zombies that can teleport, reverse gravity, go faster than light, go back in time, and simultaneously be themselves and be something else, or simultaneously do something and not do it. Because that's the same as other zombies we've seen on screen so far; in fact, more interesting.

As an optimist, I'll close by focusing on the one positive aspect of zombie films; thus I leave you with this compilation of heads exploding, which features a lot of zombies.

For the Clarionites: Best Posts

Hello Clarionites! As discussed, here is a selection of posts from the last year and a half. Enjoy!

Science Fiction Reviews and Essays

#Shortcuts in World-Building
#More Reviews of Mieville's Embassytown
#Aliens and Their Strange Obsession With Intelligence
#The Law-Giving Machines
#The Dying Earth Genre As Horror of the Irrational (also featured at The Night Lands)
#What People Often Don't Like About Fantasy
#An Optimistic Turn in Science Fiction


Science Fact: Interstellar Travel, Chemistry, and the Fermi Paradox

#Cassini Measures Enceladus Chemistry
#Fomalhaut
#Asteroid Mining and Detecting Others' Von Neumann Probes
#A Moore's Law Argument for Panspermia
#Mars, Antarctica, Jamestown: Environmental Constraints on Human Expansion
#Close Passes Between Stars and Cross-Contamination
#The C-Index: How Far Away Could We Hear Ourselves?
#Where to Find Von Neumann Probes - And How They Work


Favorites of Internet Philosophy: Singularities and Simulations

#A Singularity Solution: Anti-AI AIs
#Singularity Solutions
#Some Ongoing Problems of the Simulation Argument


Science Fiction and Local Interest

#Los Angeles Always Makes Me Think of The Terminator
#The 70s Science Fiction Landscape of California
#The Very Large Array and Skynet
#The Tacoma Narrows Bridge Designers

Stories Without Characters and Plots

We're told that all fiction, and especially commercial fiction, must have characters and plots. Is this really true? In the last couple years I've noticed a number of outstanding science fiction stories which are really expositions of ideas, with no pro/antagonist conflict to resolve, no clear narrative current; it's a lot like reading non-fiction, and it's often excellent. What's more, I find that imagination can fly more freely in this style of fiction because the writer can keep piling on ideas and innovations one after another, and isn't that why we're reading speculative fiction, for ideas? If you disagree and you like Borges, then you have some explaining to do. Even when he does have characters, they often function only to introduce a puzzle at the beginning of the piece, and then exeunt as the ideas take center stage. (Not everyone appreciates fictions of ideas, or they miss the boat entirely; more here in the context of criticism of Mieville's Embassytown.)

Granted, it may be good advice for aspiring writers to master the more traditional and likely easier structures of modernist, character-and-plot driven narrative fiction - but there are subgenres of science fiction which are clearly about ideas, and they suffer for their conservative insistence on crowbarring characters into the story. This is hard science fiction's cardinal sin; how many stories have you read that seems grudgingly salted with characters whose dialogue is basically to read aloud the technical manual for some interesting concept the writer is considering?

Since I greatly enjoyed Ken Liu's Hugo-nominated story, I've been devouring everything by him I can find, and his "The Bookmaking Habits of Select Species" is an excellent example of this expository style. The story delivers exactly what the title promises: a description of how various aliens write and regard books, and it's nothing short of addicting. Rarely have I been so sorry when a story ends. Liu also seems to anticipate his reader's thoughts and objections, and you feel as though you're in a dialogue with him as you read. (He's a practicing attorney; this may not be a coincidence.) Kij Johnson (whose Spar I loved) is nominated for the Hugo for Mantis Wives, which is more clearly allegorical, but getting to what that allegory places more demands on the reader.

The writer I've seen doing this most explicitly - and discussing it explicitly in inteviews - is my favorite new writer, Yoon Ha Lee; another piece linked here.

Close Passes Between Stars, and Cross-Contamination?

Stars move relative to each other, and sometimes they get close. At the moment our closest neighbor is Alpha Centauri, and it's going to get closer. Currently it's 4.3 light year, but 28,000 years from now it'll be just a hair over 3 LY. From the figure below you can see that 40,000 years from now Ross 248 is going to get a little closer than that:


The potential impact of close passes is significant to astronomers, who have already been looking at these events, past and future. Close passing stars are ominously called nemesis stars, since they could cause comet showers, extinction events, and even planetary ejection from a stellar system. It's also interesting from the standpoint of exchange of material between star systems. We know for certain this happens, because the material returned by the Stardust mission from the Wild-2 comet has a different nitrogen isotope ratio then the rest of the solar system - the comet originated from a different star. It's likely this occurred because another star captured a comet with a hyperbolic orbit after it escaped its parent star's gravity, but could this occur by "direct" capture?

You can see from the figure above that there are no close shaves in our future, assuming our surveys have detected all nearby objects* and our proper and radial motion calculations are correct. But there is one coming nearby: in 31,000 years, the Sun's neighbor Epsilon Eridani will be less than 1 LY to Luyten 726-8AB, close enough to disturb a hypothetical Oort cloud around the system, even if not the dust disk around the star; the nemesis will be closer than 1 LY for 4,6000 years. (One of the interesting things about these encounters is that they happen on a scale of thousands of years, pretty fast in comparison to most astronomical events.)

So what are the closest encounters likely to have happened to our neighbors? This paper by Deltorn and Kalas first looked for encounters with Vega, Fomalhaut, and Epsilon Eridani over the past million years, because they have asymmetric debris disks. They found that these stars respectively had 4, 6, and 3 encounters of (at closest) 1.6 LY (no word on how that frequency of encounters compares to other stars with less strange debris disks or no disk at all).

In the course of looking at Hipparcos data for 21,497 nearby stars, they did find an extremely close encounter 350,000 years ago between Alpha Fornacis (HD 20010) and HD 17848, at 0.265 LY. For reference, that's 16521 AU. The comet with the farthest aphelion known is a NEAP-discovered object C/2002_L9, with an aphelion of 14245 AU. There are surely more, so the encounter between the two stars above is surely close enough to capture and therefore exchange material.

The reason this is interesting is that if life exists elsewhere in the universe, and it can move between stellar systems, we're most likely to detect artifacts on low gravity bodies**, especially if they're self-replicating. Comets and small icy moons in our own solar system are a good place to start. Whether what we find are von Neumann probes or space algae is unimportant, and in any event likely indecipherable at first discovery. The same arguments certainly apply to any objects moving under their own power. If these objects are going to move to another system, they're more likely to do it when the two systems are close. This makes a recent finding by Forgan, Papadogiannakis, and Kitching all the more interesting: that using gravity-assist is faster than powered flight alone by two orders of magnitude for galactic exploration, and even adding power to gravity-assist doesn't appreciably speed it along. Their conclusion is that the velocities achieved in their model are still slower than they would need to be in order to say "no aliens have come to the solar system, and if they were around, they would have by now, so there aren't any." (There's more below about the first part of that statement.) This is all to say, if gravity-assist is really the way to go, then it's possible for there to be interstellar "backwaters", where you can't get there from here.

A. Powered	B. Gravity-assist

Powered and gravity-assist models of interstellar travel.
In the gravity-assist model there can be "backwaters"
that are very difficult to get to
If aliens are traveling through the galaxy by powered flight, there's less sensitivity to the distribution of stars, and no sensitivity to starting point: you can turn in any direction you want and travel straight there, and one direction is as good as another. But in a gravity-assist model, there are constrained paths from one star to another. That is, over a few thousand years, you might be able to get to one 20 LY away but you can't get to the one 3 LY away because of your starting point, and the lack of stellar companions or other bodies you might need for your slingshot.

So if it's not just distance, but also the detailed distribution of interstellar geography that matters to the spread of replicator material between star systems (either probes or "living things"), periods of anomalously close contact between stars make a difference. Previous I argued that, to increase our chances of detecting life in other stellar systems, we should look at systems with super-Earths (more gravity therefore thicker atmosphere to preserve simultaneous gas and liquid phases, and more surface area for replicator chemistry to use as reaction vessels); we should also look toward the galactic core - the stars there are older (have had more time for life to evolve) and they're distributed more densely. In addition we should focus on stars that have had close encounters like this, as spreading zones. If it's possible for life to move between systems, it's most likely to move between close systems. Pejoratively, think of it like this: promiscuous stars are the ones most likely to catch something!

So is there anything interesting about the two close-encounter stars? HD 20010 is an F-class star, fairly near at 46 LY from Earth. The system has an IR excess, which means dust. The star is 2.9 billion years old, and is just leaving the main sequence. For comparison, at the corresponding point in the solar system's history, eukaryotes were only just starting to pull ahead of bacteria, but the ancestors of flagellates and ciliates hadn't yet split, and the atmosphere was still only 3% oxygen. Trilobites were still far-future science fiction at that point. The other star HD17848 is now 165 LY from Earth; it's an A-class which also has an infrared excess and therefore dust disk.

Regarding the original three stars in this paper, it turns out Fomalhaut does have a very strange dust ring and a solar system with Earth-like planets.

At this point, strangely dusty planetary systems that have recently been perturbed by near-misses from nemesis stars are best explained by what we already know in astronomy: that there were multiple impact events and the dust is either settling or some non-miraculous process is replenishing the disk. That said, it's still worth paying special attention to "promiscuous" stellar systems for anomalous findings.


*It's risky to assume we've discovered all "nearby" objects. The second and third closest known stars to the solar system were respectively discovered less than a century ago, and this year.

**Detecting extrasolar life by detecting their signals carries far more assumptions than looking for artifacts; for e.g., that they're intelligent, that they use similar technology, that they don't mind being overheard or for some reason want to be overheard by other intelligences, and that, most dubiously, we notice and realize what we're listening to when we detect one. Material artifacts are more likely to be recognizable against background and give the added benefit of proof that transit by replicators between stars is possible.