One of the specialties of science fiction—and to some extent fantasy—is to evoke a sense of strangeness.  In dealing with the alien, the cosmic, that which is far away in space or time, SF can make us feel we are encountering something that passes the limits of our knowledge or understanding.

This isn’t as easy as it looks.

The Used and the Unusual

Since at least the original Star Wars (1977), it’s been good practice to portray a “Used Future.”  Star Wars gave us a world full of beaten-up, grimy equipment that looked as if it had been duct-taped together.  This is generally a good technique.  It adds realism.  We feel at home in a world where everything is not perfectly cleaned and aligned; it’s like where we actually live.  There’s a sense of familiarity.

One opposite to the “used future,” of course, is the kind of earlier SF movie that was full of shiny, spotless spaceships and immaculate gizmos.  But the sense of familiarity also has its own opposite:  the thrill of unfamiliarity.

One way the challenge arises is with extraterrestrials.  Suppose a story has us meeting intelligent aliens.  If they seem just like us—“rubber-forehead aliens”—they won’t be convincing.  We expect something from another world to be different.  The writer or director has to show creatures, technologies, behaviors that are unlike anything we’ve seen on Earth.

Escher: Wallpaper CaveYet these things must also be believable.  Something that simply looks random or arbitrary, like an abstract swirl of colors, won’t convince us we’re seeing a real thing at all.  How do we thread the needle between the too-familiar and the unintelligible?

Just Alien Enough

Natural laws do enforce certain constraints on physical objects.  But other characteristics are a matter of custom, design choices, or aesthetics.  To show something convincingly alien, we need to know the difference.

Alien ship from movie ArrivalSometimes a single feature can be odd enough to alert us that we’re “not in Kansas any more.”  The alien ship that appears in the movie Arrival looks strange at once, because it’s smaller at the bottom than at the top.  It looks as if it’s upside-down or sideways. Not the way we’d build, yes.  But is it physically impossible?  Nope.  The ship isn’t on the ground, balanced implausibly on a narrow end.  It’s floating in the air.  This not only frees the ship from the usual need for wheels or other supports; it also introduces a second, subtler strangeness.  When we humans land somewhere, we expect to land, to set ourselves down securely on a surface.  These folks seem quite comfortable floating just above the ground.

A classic example is Arthur C. Clarke’s Rendezvous with Rama.  A massive spacecraft—a spinning O’Neill cylinder—enters the solar system, apparently inert.  A human crew matches course to explore it before its hyperbolic orbit takes it out into interstellar space again.  The ship begins to “come alive” around them—but there’s no sign of intelligent life aboard.  The explorers find one strange and amazing feature after another.  The purpose of some becomes clear:  the long, shallow rectangular valleys turn out to be immense lights that illuminate the interior.  But they never find out the reasons for many other objects.  In the end they have to cut loose from the vessel, letting it go on its mysterious way.

Rendezvous with Rama interior illustrationClarke’s mastery of clear detail—how the airlock doors open, for instance—gives us the necessary sense of realism.  But leaving many things mysterious evokes the sense of mystery and wonder that is among the most distinctive experiences in science fiction.  The unfamiliar is clearly and concretely depicted, but the purpose remains obscure.

(Parenthetically, I advise paying no attention at all to the dreadful sequels Gentry Lee wrote to Rama under Clarke’s direction.  They make the classic mistake of erasing the mystery without replacing it with anything at all interesting.  As with certain other sequels, the only thing for a conscientious reader to do is declare them non-canonical and pretend they never happened.)

For another Clarke treatment, remember 2001:  A Space Odyssey.  The mundane and even humdrum character of the long space voyage makes the psychedelic sequence at the end feel even weirder than it is in itself.

Sufficiently Advanced Technology

Extraterrestrials need not be involved.  Distance in time or space, and the concurrent advances in technology, can also provide a good foundation for the sense of strangeness.  (It was, after all, Clarke’s Third Law that “any sufficiently advanced technology is indistinguishable from magic.”)

Among the numerous virtues of David Brin’s Hugo-winning novel Startide Rising is that sense of entering a new and unaccountable world.  His Earthly spaceship crew of “uplifted” dolphins, with their small group of human companions, use advanced techniques that are still recognizable to us.  But they’re dealing with galactic cultures that draw on hundreds of millions of years of accumulated science.  The results can be mind-boggling.  One species, for example, travels by using a captive creature that creates portals “by the adamant power of its ego—by its refusal to concede anything at all to Reality.”  This isn’t your grandmother’s hyperdrive.

Toy stack of ringsThe body of another species, the Jophur, consists of a stack of distinct rings, like a child’s toy.  The Brothers of the Ebony Shadows employ a probability weapon that sends out “waves of uncertainty.”  The fact that these species are nonhuman is incidental to the fact that their immense background of far-advanced science lets them use techniques that seem to surpass our understanding.

For a purely human example, let’s look at Arthur C. Clarke’s The City and the Stars.  (Clarke really had the knack for this sort of thing.)  The main character, who bears the pedestrian name of Alvin, lives in Diaspar, the last city on Earth, billions of years in our future.  The city’s structure does not erode or decay; it’s maintained by “eternity circuits” according to the model held in its master computers.  The people do not die in a conventional sense.  After living for a thousand years, each individual walks back into the Hall of Creation and is dissolved—but is also retained in the memory circuits, to be rematerialized eons later.  Thus the population of the city is always changing, but the individuals continue.  And that’s only the beginning . . .

The City and the Stars, illustration

Exotic Ways of Life

Technology is one thing; behavior is another.  The City and the Stars does a terrific job of imagining how the society of Diaspar is shaped by the extraordinary conditions under which its people live.

When I read Yoon Ha Lee’s Ninefox Gambit, it was billed as ‘military science fiction’—but it’s nothing like the general run of military SF.  The six factions in the story make use of technologies that create real-world effects based on “formations” of people and their consensus beliefs.  Much of the plot revolves around a revolt based on “calendrical heresy”—which is just what it sounds like:  deviation from the standard calendars.  In Lee’s world, calendrical uniformity isn’t just a matter of convenience, but of crucial importance.  The resulting society is correspondingly peculiar.  Reading the story makes you feel as if you’re constantly being knocked sideways.

Greg Bear’s City at the End of Time combines present-day characters with those living in a city one hundred trillion years in the future.  The far-future people consist of “noötic” or virtual mass, are defended by “reality generators,” and are trying to fight a cosmic entity that’s trying to destroy the universe by disintegrating its history, acting backward through time.  The present-day people in mundane Seattle keep us grounded, but trying to understand the end-of-time characters and what they are doing requires a constant stretching of the imagination.

Strangeness and Wonder

The sense of strangeness or mystery is one form of the “sense of wonder” often used to characterize science fiction.  It takes us out of the mundane, makes us strain to conceive the inconceivable.  We’re often told that world travel expands our horizons by exposing us to different places and cultures.  Science fiction goes further:  it exposes us to ideas and places and people that don’t exist in the world at all.  At its limits, SF seeks to show us more than we can even comprehend.  The lack of reality is compensated by the greater impetus to go beyond our mental limitations.

To achieve that experience, we seem to need the right combination of the familiar and the exotic.  The weird stuff at the end of 2001 isn’t entirely successful, in my view:  it’s too strange.  Not only do we not understand what’s happening; we don’t quite feel there is anything to understand.  You have to read the book to figure out what’s going on.

But when we have enough groundedness to effect the “willing suspension of disbelief,” yet enough mystery to defeat (in part) our attempt to understand, the combination is uniquely fascinating.  As I noted at the beginning, this isn’t an easy balance to strike.  But the payoff makes it worth attempting.

How to Stage an Alien Invasion

We love our alien invasions.  Since The War of the Worlds (1897), poor Earth has suffered a steady stream of hostile arrivals—frequently from Mars, but recently from farther afield, as the possibility of other intelligent life in our solar system wanes.

We have one coming up this month, with the June 24 movie premiere of Independence Day:  Resurgence, a sequel to one of the more successful invasions of the last twenty years.  It seems like a good time to look closely at our opponents.

Footfall, a 1985 novel by Larry Niven & Jerry Pournelle (still available in print), is not only a great yarn, but a textbook model of how to write a modern invasion story.  We can look at it as a test case, like an existence proof in mathematics:  What kinds of conditions have to be fulfilled for a believable alien invasion, given what we now know about other planets?


Let’s define the target.  We’re talking about the good old classic invasion story, where the bad guys show up in person, make a direct assault, and we beat them.  That isn’t the only possibility.  There are other variants, such as infiltration, or scenarios where the Earthlings lose and end up a subject species.  But let’s look at what premises make a triumphant Independence Day-style plot viable.


It was easy for Wells.  His relatively nearby Martians could fire off a series of cannon shells, more or less, to land on Earth, break out their tripods, and mount their campaign.  Wells’ tour de force ending, of course, has the Martians beaten not by human opposition, but by humble bacteria.  (Arguably the best moment in the original Independence Day is when Jeff Goldblum realizes we can best the enemy by using a contemporary analogue of the Wellsian microbes—a computer virus.)

But modern invaders have to come from a greater distance.  Regrettably, none of the plausible abodes of life in the solar system have panned out.  Gone are old-time SF’s sweltering jungles of Venus, the canal-crossed deserts of John Carter’s Mars.  Until we’re ready for an attack by potential microbes from Europa, or hypothetical floating denizens of Jupiter’s atmosphere—neither of which, if they exist, have shown any signs of capability for interplanetary excursions—we have to look to interstellar sparring partners for a really good invasion.

This intensifies a long-standing problem with invasion stories.  If they got here, and across the interstellar gulfs at that, their technology must be literally light-years ahead of ours.  How can we expect to beat critters with such vastly advanced technology?  The balance of power is inherently skewed against us.

Paired with this is the question of motivation.  Why are they here?  What do the invaders want that would drive them to come all the way to Earth for it?

This is the easiest place for invasion stories that aren’t built on sound science to go astray.  We need only mention the 1983 TV mini-series “V,” which, though it had many admirable aspects, fell sadly short on the science side.  V gives not one, but two, implausible motives for the seemingly-benevolent Visitors.  They’re here to steal Earth’s water—as if there weren’t vast amounts of ice scattered around our solar system, and probably most other systems, for the taking.  And they’re here to eat us; apparently not only are humans compatible with a completely alien biology, but we’re a tastier treat than more edible and obtainable animals.  Sensible extraterrestrials need a better reason to traipse across the light-years than a local hamburger shortage.


Niven & Pournelle’s epic adventure handles both these questions so beautifully that it might have been plotted specifically to answer them.

Our not-quite-friendly visitors, the fithp (the singular is fi’), arrive in a large interstellar vessel, which launches smaller ships to conduct the attack.  Why are they here?  They’re looking for Lebensraum — living space.  The fithp have been exiled from their homeworld as the result of a conflict among factions—like the Protectors in Niven’s novel Protector.  They need a new place to live.  Among other things, this means “defeat is not an option”:  they can’t go back.  That ups the stakes.

But this exile premise also solves some of the balance-of-power problems.  The fithp’s resources are strictly limited.  There won’t be any reinforcements.  They can’t bring anything more from their homeworld.  All we have to do is defeat this batch of opponents, and we win.

Niven & Pournelle strengthen this limitation on the aliens, and incidentally increase scientific plausibility, by making their mother ship Message Bearer a slower-than-light vessel — a Bussard ramjet.  Their journey takes decades.  This distances the fithp even further from any potential homeworld support.  The authors also use it to introduce another twist:  there’s dissension between the space-born fithp, on one hand, and those who lived on their homeworld and are now awakened from suspended animation, on the other.  This division becomes important as the plot develops.

Without having to account for faster-than-light travel, Niven & Pournelle can give the fithp technology that isn’t too far ahead of our own.  Human numbers—and political, psychological, social characteristics—can make up for the technological imbalance.

In addition, the fithp don’t fully understand their own technology.  They’ve learned a lot of it from records left by their Predecessors, rather than developing the science themselves. This makes them less able to innovate.  By contrast, the humans’ response is a masterpiece of improvisation.  We make the best of what we have.  This, too, helps even the scales.  (Lesson for humans:  Continue fostering that STEM education.)


In the course of this worldbuilding, Niven & Pournelle give us fully fleshed-out aliens, with a coherent culture and society, understandable but different from our own — not an easy task.  Among other things, the fithp are sympathetic characters.  They are people, not just faceless attackers.  We see events from their viewpoints as well as our own.  This makes the story not only more believable, but more interesting.


The original Independence Day scores modestly on these two plausibility counts.  Motivation:  The aliens travel the stars like locusts, stripping planets of their resources.  No details are given, but the basic idea is not unreasonable, particularly in light of contemporary environmental concerns.  Balance of power:  We’re hopelessly behind in technology—but the aliens’ laziness (using our own satellites for signaling), Goldblum’s bright idea, and a captured alien ship get us (barely) over the hump of the willing suspension of disbelief.

We’ll see shortly how these premises play out in the Independence Day sequel—applying the Niven & Pournelle standard.