Evaluation will be based partly (∼7 %) on secret
observation by intellects vast and cool and unsympathetic, partly
(∼12 %) on direct use of the Probe, and partly
(∼98 %) on guesstimates derived from arbitrary
I'm at a loss for an explanation of quite why I should have
written this, apart from the obvious fact that it's yet another
foray into the world of quasiscience
cliché‐mockery. It lets me add a few more site‐internal
links, recycle offcuts from my guides to SF
Exobiology, and put on display the routines I've
got bored with rehearsing in arguments.
Guide to Fermi's Paradox
The big mystery in SETI (the search for extra‐terrestrial
intelligence) is why we should have to search for it at all.
There's nothing obviously special about Earth; starsystems much
like ours have been around for billions and billions of
years. So shouldn't outer space be crawling with lifebearing
planets, technologically advanced aliens, and unmistakeable
evidence of inhabitation? Shouldn't somebody already have
come looking for us? As the Italian physicist Enrico Fermi
put it, “Where is everybody?”
Naturally, it's only a paradox if we're right to imagine that the
ETs are out there. Somewhere in our chain of assumptions
there's got to be a misstep – a Great Filter that's
winnowing our imagined multitude of space‐opera galactic empires
down to approximately zero. But where is it? Let's run
through the options:
Maybe planetary systems are rare. This idea
used to seem highly plausible; but astronomers have discovered an
awful lot of stuff going around nearby stars lately, so it's out
of fashion. Mind you, it's all seriously weird stuff, so
perhaps what they're detecting is the junk that's messed up all
the potential biospheres. Well, at least it improves the
likelihood of extra‐solar planets having interesting things in
their skies to stand in for the absurd fire‐balloon nightlights
the SCI‐FI Channel has been promising us… people don't appreciate
what a great light‐show Luna puts on, compared to, say, Phobos
Maybe life doesn't appear very often. Somehow
it's taboo to mention that possibility at all these
days – dead Martian sands don't sell newspapers or
attract research grants. However, even if life isn't so
common that we can afford to wreck Earth and move next door, it
still might be common enough that anyone prepared to spend a few
centuries freeze‐dried in transit could expect to get someplace
where the air's only a slow poison. That would mean a
galaxy teeming with potential ETI… but we really have no idea
what the odds are.
Maybe it's rare for intelligence to evolve.
That is, perhaps the microbes in most alien seas come up with
some obvious alternative to being multicellular that outcompetes
all opposition and stops any interesting “higher” fauna ever
developing. Or perhaps the biochemistry of Earthly
vertebrates is unusual and all the comparable creatures elsewhere
find the warm‐blooded big‐brained lifestyle unprofitable.
I'd be mildly surprised if this was true – life on
Earth made it all look so easy, beating the deadline with aeons
to spare – but again, without a good statistically
significant sample of laboratory planets, who's to say?
Maybe intelligence rarely leads to sufficiently high
technology. Now, it's easy to dream up doomsday scenarios
in which With a Tragic Irony the ETs are Destroyed by Their Own
Creations as soon as they invent nukes (or fire, or VR Tetris, or
warpdrive)… but it's hard to imagine every single sapient race
messing things up so badly no replacement civilisation ever
arises. Once you're thinking on a galactic scale, it hardly
matters if they do suffer a Dark Age or two, or get stalled in
the palaeolithic – they can keep ringing the genetic
and memetic changes for millions of years, and if the cultural
snowball ever gets rolling then science and technology are pretty
much downhill all the way. They may not come up with the
same problem‐solving techniques in the same order, but as long as
they keep finding new problems they'll have to keep building on
the toolkit they've got.
Maybe the technologically advanced societies aren't
interested in exploring. This one again sounds strained:
we're the only race ever to evolve that isn't autistic?
Sure, they might not be conquistadors dedicated to settling every
available rock, but that's fine. We can already imagine
ways of using foreseeable technologies to get probes to every
last corner of the galaxy within a mere couple of million years;
if the average alien isn't interested enough to insist on going
there in the flesh, and waits until the task's trivial before
bothering to start designing automated probes, then if anything
that's likely to mean an obviously intelligence‐filled universe
sooner rather than later. After you've launched a
self‐replicating interstellar explorer AI, it doesn't matter what
happens to you – your culture will come into contact
with ours sooner or later.
Maybe the galactic explorers have indeed found us,
and have been watching us for millions if not billions of years,
but they're hiding, like traditional little green men. The
problem with this idea (apart from its sheer tinfoil‐hattiness)
is that the fewer inhabited worlds there are, the more talking to
us becomes a rare and valuable opportunity; and on the other hand
the more there are, the more races have to independently come up
with a reason for abiding by a strict ultra‐long‐term policy of
pretending not to be there.
So; there's no good obvious candidate for the Great Filter.
For such a tenuous piece of reasoning from so little hard
evidence, this has surprisingly big and unwelcome implications,
since we know the filter's somewhere, and it might be somewhere
that's bad news. Real evidence of life on Mars or
Europa becomes something we should be hoping
never to find! After all, the weaker candidate #2 is, the
more danger it puts at position #4 where it might be about to
filter us. We're left having to consider
possibilities like strong nanotech being a universally lethal
thing to research…
LOST PROPERTY IN SPACE
A BDO‐Spotter's Handbook
It's conceivable that a super‐advanced space‐travelling
civilisation used to be out there, but – oh, bad
luck – we just missed them! In which case they
might have left some fun pieces of industrial palaeontology lying
around waiting for us to find and investigate them. And I
don't mean crumbling ancient cities or drifting
space‐hulks – I mean truly vast pieces of machinery.
People who are trying to be serious about this kind of stuff
usually call them “megastructures”. Unfortunately,
architects have started using that term to refer to mere office
blocks; and on the whole rather than retreat up the SI prefix
table to “gigastructures”, I prefer going straight for the
SF‐fannish jargon term: they're “Big Dumb Objects”.
Perhaps the most famous kind of BDO (so mainstream it has even
been in Star Trek!) is a shell built
around a star to collect all of its output for the owners'
use – the “Dyson Sphere”, a concept invented by the
Dyson who didn't invent bagless vacuum‐cleaners. Oh,
and when I say “sphere”, I'm not necessarily talking about a
solid sheet of ironmongery englobing the sun like some humongous
work of Victorian engineering, though admittedly that is how it's
usually depicted. The more reasonable approach is to
arrange swarms of energy‐gathering satellites in carefully
Mind you, if you want to squeeze all the power out of a star
efficiently, this approach may be a good start, but it seems a
bit half‐hearted! I'd have thought what you want to do is
throw an electromagnetic bottle round the star then decant all
that plasma into a couple of zillion frozen‐hydrogen
comets. That way you can power your village streetlights
off nuclear fusion for the rest of time, or alternatively charge
up a single planet‐sized antimatter firecracker then light the
blue touchpaper and retire immediately.
Meanwhile, one other use for circumstellar constructions of this
sort is as an unusually literal “stardrive” – the
“Shkadov Thruster”, which converts your entire starsystem into a
self‐propelled solar‐sail vessel!
Given the improbability of encountering aliens whose
technological level is within millennia of your own, the only
point of commissioning astro‐dreadnoughts is so you can threaten
others of your own race – and you don't need a
stardrive to do that. This calls for an alternative funding
model involving some natural hazard that can only be defended
against by huge space‐based missile‐silos; but remember that you
need to take into account not only the theoretical risk per
century of (e.g.) an asteroid hitting your planet but also the
risk of a loon getting hold of the button.
Experimental killing‐machines are also a bad place to test new
software designs… and if you find one floating dormant in an
apparently lifeless region of space, don't even think about it.
Designs for residential megastructures can be classified by where
they get their gravity:
Spinning hoops, where centrifugal force lets you live on the
inner surface (this includes both rings/orbitals and the
ever‐unpopular “cosmic macaroni” design; the big ones require
unlikely building materials).
Supramundanes, which are strips or shells suspended in a
gravity‐well (such as a gas giant's), so you can live on the
outside – a sort of round‐the‐world suspension
Habitats built with artificially generated gravity, which can
thus be any shape you fancy (the inside of a Dyson Sphere, for
instance). One option if you can't manage anything better
is the pie‐dish‐shaped starship, which has a “down” while
Things are simpler if you aren't fussy about
gravity – especially if you can live without air or
radiation shielding, because then space makes a fine open‐plan
residence, and even turning your homeworld into an asteroid
belt can seem like an improvement. After all, what good
is a nickel‐iron core if you can't get at it?
But who needs a habitat that big? People inhumanly bad at
arranging their furniture? Or maybe just incredibly
incompetent when it comes to contraception? The idea of
assembling a Ringworld for the sake of Lebensraum sets off
warning bells for me. I can't help imagining a
trillion‐odd workers labouring on it for generations while
sleeping in shanty‐town orbital‐habitats… then being told when
it's finished that they can't afford the rates and that they
should be grateful the owner isn't going to demolish the slums.
I dare say the aliens might need a gigahabitat because they have
religious objections to birth control (cue visions in which the
BVM orders a BDO)… or maybe they're sun‐worshippers who want to
protect the sacred photons from falling into infidel
retinas. Once you start wondering about this kind of thing
there's no obvious limit to how strange it might get, and it's
particularly liable to result in baffling “neutronium‐henge”
For those too lazy to go exploring, how about the option of
setting up a big here‐I‐am signal and waiting for ETI to come to
you? It could be a plain electromagnetic beacon (in which
case the leftover emission wavefront counts as a sort of a
relic), but it's a bizarre sort of laziness unless you're getting
some functional advantage from your BDO –
The Lighthouse: if you're convinced there are slightly myopic
aliens out there, maybe a focussed beam's what you need.
The Transducer: how about a Dyson shell that converts a star's
output into exotic particles… tachyonic ones would be good for
getting quick replies.
The Magnet: maybe a sufficiently large vortex in hyperspace
will make your system a natural target for explorers.
Of course, it's possible for message‐sending activity to be less
innocent than it seems, but any race that goes opening mystery
attachments under Windows deserves everything it gets.
Another possible case for huge engineering projects is where the
physics of it establishes a minimum size – a
subparticle superdupercollider, “Tipler Cylinder”
time machine, or Q‑wave lens.
Experimental equipment tends to have an inherently limited
lifespan, but in principle your whole social infrastructure could
end up dependent on some such obscure piece of physics; maybe the
giant Quantum Interocitor is necessary to keep your communal
brain‐the‐size‐of‐a‐planet topped up with fresh supplies of
Refurbishing planets to enhance their ability to sustain life
isn't usually seen as megastructure engineering unless you've
built the whole thing, lithosphere, fjords, and all. Well,
you never know – it's possible your efforts might go
unnoticed by later visitors, especially if the place has been
ecoformed to suit ammonia‐drinkers rather than terraformed.
However, some of the suggested techniques are unsubtle enough to
deserve mention here, such as ringing Mars with mirrors,
disassembling Venus's planetary mantle, or igniting Jupiter.
Then again there's the kind of refurbishing you can do to your
original home. Girdle the equator with a string of
space‐elevator towers connecting to the orbital ring‐city
factories… illuminate the night sky, using the magnetosphere as a
billboard… the end result could be a planet paved with
Soviet‐grade concrete, so it would be nice to imagine we'd have
the sense to target our terraforming efforts on Earth and save
the industrial lunaforming for Mars!
SPATIAL WEAPONS AND TACTICS
Starship Combat Top Tips
There are two possible approaches to planning for interplanetary
or interstellar battles. If what's important to you is
efficient and well engineered astronautics, read the
recommendations in the left‐hand column. If you prefer
something that's going to provide good footage in the media, read
the right‐hand column, and don't forget to arrange the schedule of
Internet trailers, main release, and associated
games/action‐figures to fit your reelection campaign.
While you aren't accelerating, point your nose towards safety
and your drive‐tubes towards danger. This not only saves
time in emergencies but presents any potential attacker with
the prospect of a reaction‐drive going off in their face.
Keep your nose pointed in the direction of travel.
Where possible, use a stardrive that enforces
cinematic kinematics, such as a
stutter‐teleporter: you aren't accelerating, you're just being
continuously relocated in front of where you were.
Projectile and coherent‐radiation weapons work perfectly well
at long ranges; there's no excuse for star‐destroyers
colliding with one another when they have the whole of space
to manoeuvre in. If you can see one another,
you're too close.
Make sure your fights are dramatic by only engaging the enemy
while parked at a strategic location (such as a wormhole exit),
and/or only using blasters with inverse‐cube‐law
range limits. Never miss an opportunity to call for
Organic lifeforms make good mascots but bad pilots. When
the enemy's deploying clouds of war‐drones, each accelerating
on its own vector in its own relativistic frame of reference,
primate tree‐swinging instincts just won't cut it.
Embedded‐software journalists are one thing, but never put an AI
in charge of your Ultimate Weapon. Get Star‐Captain
Biggles to centre the cross‐hairs by hand – his brain
may be made of meat, but he's far more photogenic.
If you don't want to run the risk of your orbit decaying,
standard operating procedure should be to use a “forced” orbit
at higher than escape velocity, so that if you stop
actively maintaining it you drift away from
Given that your stardrives provide cheap hyper‐acceleration and
you're not planning on hanging around for long, gravity‐wells
are relevant mainly for the associated scenery. Remember
to park side‐on to the planet so your starboard portholes get a
There's no such thing as a survivable impact. You get
enough lethality to spare from any contact that doesn't involve
deliberate velocity matching; there's little point using fancy
gimmick missiles if they're going to hit the enemy head on at
An armoured hull will save you from drifting space‐grit, but to
fly through the Peasoup Nebula on ultradrive you need a serious
tachyon‐snowplough – and since that has to be magic
in the first place, you might as well go for the whole “divert
power to shields!” shtick.
Never look directly at an enemy starship – if it
explodes it'll be a silent (and slightly delayed) point‐source
blast as their antimatter cells lose containment, and if not
you're staring up the barrel of their laser cannons!
Either way, ophthalmologically inadvisable.
To make beam‐weapons visible in a vacuum, you'll need
side‐scatter; maybe some sort of laser‐launched
plasma‐bolt? With luck it'll also produce static‐roar
sound effects on your comms channels… as will your
manoeuvring thrusters. But what you really want is
Cherenkov radiation “vapour‐trails”.
Unless you've got some appropriate “jumpdrive”, you can only
ambush a victim in the emptiness of space by outrunning their
sensors – for instance, radar's no good against
Nobody to fight? Hunt Space Pirates! Not only
are they naturally exciting, they're also guaranteed to remain a
lurking menace to civilisation for as long as you
Asteroid belts are negligibly hazardous compared to the
junk‐strewn space around your homeworld; even deliberately
scattering “mines” is a waste of effort unless they're armed and
mobile in their own right.
Space badly needs chunky bits. Hang around in ring‐systems
as much as possible, and always fly through a planetary system
in the plane of the ecliptic (banking dramatically as you steer)
with all your hull‐mounted lights blazing.
Any strategy that involves blockading a frontier in space (let
alone hyperspace) against intruders is doomed. Indeed, why
would you have territorial borders when the Rigellians aren't
interested in Earthlike planets?
The best thing about sweeping fleet manoeuvres in three or more
dimensions is that you can usually find a map display angle that
makes it look as if you outflanked them while they were trying
to run away rather than vice versa.
The one thing you need before you can conquer an Earthlike world
is atmospheric supremacy. As soon as your military
nano‐robots have 0wn3d the inhabitants' brains, you can recruit
any infantry you need from the local populace.
Space Marines are cool. The name's a bit dumb, given that
“marine” is the one thing they aren't, but hell, give them
space‐axes and call them Special Ninja Assault Squad, what does
it matter as long as they're blowing things up!
Space Invaders Howto
I hear of more and more alien invaders these days who seem to set
out with no clear idea of what they want or how they should go
about getting it, and who unsurprisingly end up bungling the whole
operation. It's dreadfully upsetting to see Greys bawling
their eyes out, so here's a guide to best practice classified by
Quite a lot of aliens go about turning worlds to rubble, with a
variety of motives. The Vogons were fibbing about that
whole hyperspatial bypass thing, but the Daleks' old obsession
with stealing Earth's core makes some kind of sense, it being
after all a nice magnetically active one. Or you might be
the kind of people who really like asteroids (cf.
Planeticide is an expensive feat of demolition, with energy
requirements on the order of 10³² joules; but if you can create
space–time wormholes, a simple shortcut between the planet
and its star should take care of it very effectively.
Having the permanent annihilation of all life on Earth as your
primary objective is pretty hard to justify, unless maybe
carbon‐based organisms lower local property values.
I recommend prolonged antimatter bombardment – there
are some tough microorganisms in that bedrock.
Alternatively, use nanotech… but make sure it's pointed in the
Well, if a policy of exterminating intelligent aliens on the off
chance that otherwise they might someday decide to do the same to
you is sane enough for Heinlein, I'm
sure it's sane enough for bug‐eyed monsters.
A light‐to‐moderate bombardment with kinetic‐energy weapons from
translunar range should do it; the more flexible you're prepared
to be about follow‐up strikes on survivors, the more of the local
ecosystem you can afford to leave standing. Or you can go
for biotechnological subtlety and just beef up the common cold
with a few traits from Ebola and rabies – don't worry,
you can't catch it any more than a shark can get leaf
blight. (Or, use nanotech. In fact you might as well
tack that alternative on the end of each of these
entries – nanotech's boring that way.)
For interplanetary imperialism to make sense habitable worlds
have to be extremely rare, and world‐to‐world travel has to be
extremely easy. If you were planning to invade by a
slower‐than‐light voyage in multi‐generation starships, then
don't bother attacking when you arrive – now you've
got the hang of living without a planet it's easier to build more
of the starships instead.
But assuming you still want to do it, you might as well use the
same approach as for genocide. Or
ecosphericide… you'd be redecorating the place
Coming to Earth to steal our water (à la “V”) makes
about as much sense as breaking into a bank to steal the
floorboards. The thing you're after has to be something
unsynthesisably biological or you'd be better off setting up your
tritium mines, hydrocarbon refineries, or whatever in some
uninhabited corner of space.
Whatever it is, persuade the local yokels to grow it as a cash
crop. For example, if all‐natural organic free‐range babies
are the perfect ingredient for tentacle lotion, point out to each
bunch that after all, they can use foreign infants!
Inhabited planets are the last place you'd go for fuel resources,
let alone raw energy (try the big glowing thing in the sky
instead). Still, it's imaginable there's some special
power‐source like Atlantean Orgone Crystals or Cheddite Unleaded
that's only available locally. Hokey, but imaginable.
Interspecies trade (as opposed to grabbing anything you fancy in
exchange for a few shiny trinkets) is tricky when one side holds
the title deeds to a planet and the other has staked out the
remainder of the observable cosmos, but if several different
Ferengi corporations are racing you to buy up local
virtual‐tourism rights then it becomes worth the effort of
ripping them off.
Hrmm, playing the futures market must be much easier when you can
What, so you've developed interstellar invasion technology, but
you're so ungifted at robotics that you need manual labourers,
and so bad at coming up with weaselly employment contracts that
keeping slaves is actually cheaper? In that case you're
probably better off sticking to the drudge work yourself and
getting human management consultants to be the masters.
But whatever the exact job description, there are billions of
potential applicants; just call for volunteers – you'd
be surprised how many will step forward to welcome their new
If you're so desperately insecure that you constantly feel the
need to force others to acknowledge their inferiority, then once
you've finished taunting your goldfish you might want to invade
some planet full of balding primates. Just a suggestion,
Fake up a full Hollywood‐style invasion (complete with
raygun‐toting mock‐aliens), and/or induction into the
Interstellar League of Tribal Chiefdoms.
Invading a mudball like Earth would be insane,
obviously – it's got no resources worth seizing.
But that's just the sort of crazy thing your rivals in the Great
War would do, so you're obliged to invade anywhere that's
tactically significant before they do!
There's no need to hurt the locals, though. Give them all
invulnerable cyborg bodies and they can even help out with token
bits of unskilled labour in your war‐machines' maintenance
pits. They'll thank you later, once you've pumped the
appropriate neurochemicals into their brains.
Any new society assimilated into the galactic melting‐pot brings
uniquely valuable novel insights and perspectives,
apparently. So try to catch them before they start
homogenising into one big global village; then once you've
harvested their ethnic diversity you might as well “plough them
back in” so as to get the next crop of novelties out of the
planet's successor culture ASAP.
The easiest way of making civilisations implode is probably for
the ambassador to tell them their religions are literally true.
Something like the above can also apply to the
planet's evolutionary resources – “ooh, woodpeckers,
that's a neat trick” (or indeed, “ooh, Bacillus pallidus,
that's a neat trick”). You've arrived a little late to
collect groundsloths and dodo‐pox, though, so you'll probably
want to do some weeding.
Nukes might seem perfect for this job, but don't overdo the
radioactivity: you're adaptation‐farming, not mutation‐farming.
Dining on the biochemically alien fruit of another evolutionary
tree is only likely to do you any good if what you're after is a
particularly foul‐tasting slimming aid. But maybe you're
visiting Earth because you're fond of cats; in which case your
advanced cat‐scanning technology might have told you what they
really dream about eating.
Er… you do realise this just isn't going to work out, right?
Try asking Google.
SPACE WITHOUT FRONTIERS
While “researching” all this I've run into several pages
advocating a position that seems dafter the more often I see
it – the idea that humanity should throw all its
energies into filling the Milky Way with self‐sustaining
colony‐worlds so as to reduce the risk of extinction when Sol goes
red giant in five billion or so AD. Here's an alternative
proposal: we round up all the gung‐ho idiots so keen on exhausting
our planet's resources and fire them out of a catapult in the
general direction of Alpha Centauri. That's a much better
way of safeguarding our survival.
Besides, why should we care whether the cosmos will ever run out
of hominids? It's not as if our evolutionary descendants at
that distance would be recognisably human! And while the
development of true “artificial intelligence” is a way off yet, on
a geological timescale it's the AIs we should be thinking of as
our descendants, not their pet monkeys. As long as we avoid
doing anything irresponsible in the short term, we can expect the
long‐term survival of our intellectual offspring to take care of
So by all means let's have manned bases anywhere we have business
doing things that can't be automated; it might even make sense to
terraform Mars, eventually. But there's no need to dress up
squalid factional land‐grabs as some sort of grand cosmic
destiny. Exporting concepts like political boundaries,
territorial conquests, and military arms races into space sounds
like a good way of ending up fighting wars of independence against
our colonies – and Mutual Assured Destruction won't
help anybody's survival chances.