How to hover just a little bit off the ground

In my ongoing quest to consider how to accomplish all sorts of fictional feats fictionally, I must confess to being a little bit stumped by a recurring one. Flying is one thing but hovering just a little bit is a repeated visual indication of futuristic technology. Star Wars in particular is replete with a kind of hovering-a-bit technology that transitions from a handy way for moving heavy object, to vehicles that fly very close to the ground, to presumably the full-on flying vehicles shown on Coruscant.

How best to even describe this? A kind of limited anti-gravity? Intentionally restricted flight? Whereas many other fanciful physical effects in science fiction have clear rules, the limited hover is typically under explored. However, given the command of forces needed for the standard artificial gravity required by space-opera to keep everybody walking around, it makes sense that a kind of limited neutralisation of gravity also makes sense.

We can throw in some rules. Firstly the technology we currently have for hovercraft doesn’t count. The science-fiction hover is noiseless and unobtrusive. It is meant to look effortless beyond maybe a glow or a soft hum. Hovering by the means of big turbines blowing air doesn’t count. Similarly, while it might consume some power, hovering science-fictionally is shown as inexpensive. I think I recall a kind of animal drawn cart in The Mandalorian where the cart itself had not contact with the ground, suggesting a technology that just sort of works once it is up and running.

Likewise, it is technology that doesn’t require special surfaces to work. It is a lot easier to imagine devices being able to hover within the Starship Enterprise because the whole ship must have a highly complex control of gravitational forces (as well as engines that literally warp space). Yet, it is not something we do see within Star Trek. I assume we don’t see it in Trek because it would have been a tricky effect in the 1960s and hence didn’t become a ‘thing’ for Star Trek. For Star Wars, Luke’s speeder appears to hover using a neat practical effect involving mirrors and from that point on hovering became a thing within Star Wars.

Famously, Back to the Future 2 introduced hoverboards as a near-future technology that we were promised but which clearly hasn’t arrived. The hoverboard also lives in this unclear space between something that is almost but not quite a full on flying machine but with an implication of cheapness and simple utility. It’s hard to see how the fictional 2015 could have cheap hoverboards for teenagers without having the same technology everywhere.

Of course magnetic levitation is a real thing (https://en.wikipedia.org/wiki/Magnetic_levitation ) and that also gives a clue for the concept we are looking for. “Levitation” is the concept we are looking for but techniques such as acoustic levitation (https://en.wikipedia.org/wiki/Acoustic_levitation) don’t really match the kind of science-ficitional levitation we are discussing. Likewise, real-world examples like maglev trains don’t come close to the kind of hovering within the science fiction trope. Optical levitation perhaps has some of the features but it is currently only possible with tiny objects.

Of course, I’m not interested in building an actual levitation device but rather hand-waving at a fictional one.

  • Control over the geometry of space-time. That sounds grand but it is implied by the existence of artificial gravity on space ships. If you can walk around the Millennium Falcon, then there is the technology to manipulate gravity at a very fine level. Quite how that translates to hovering, I don’t know.
  • Scaled up manipulation of fundamental forces. Of course everything in the universe is under the sway of forces that repel and attract. Repulsive forces are what stop everything in the universe just shmooshing altogether. At a fundamental particle level, forces can be attractive or repulsive at different differences. Our levitating slab of frozen Han Solo may be sitting in a sweet spot of altered fundamental forces of nature. Gravity is stopping things from floating away completely but the natural repulsion of matter is operating at an exaggerated scale.
  • It is actual flying. What I mean is the technology for levitating is actually whatever the routine technology for flying is but some how intentionally limited. An engineer can take a screwdriver to one of those Star Wars levitating palettes, switch off a limiter of some kind and have a full on aircraft.

Invasion of the Body Snatchers – 1978

I realised much later that I had missed off an important subset of examples from my post on how to duplicate people. If you are some sort of plant-based alien species drifting on the solar winds you can just use pods to grow duplicates of people while they are sleeping. This is the premise of the 1955 serialised novel The Body Snatchers by Jack Finney and the more famous 1956 movie directed by Don Siegel Invasion of the Body Snatchers.

The 1978 remake of Siegel’s film is somehow both sillier and more serious. Directed by Philip Kaufman who would later direct The Right Stuff, the film is distanced in time from the Cold War Red Scare/Lavender Scare anxieties of the original. It follows a more overtly horror aspect and hence fits in with the exploration of the intersection of horror and science-fiction also exemplified by Alien in the following year. Those two films even share an actor, Veronica Cartwright who played Lambert in Alien and Nancy Bellicec in Invasion of the Body Snatchers.

Where the original film is set in a small town, the update shifted to San Francisco and has an overall bleaker feel. Famously, the film ends badly for humanity with a shot that reveals that Donald Sutherland is now a pod-person as he points his finger and makes an ungodly howl at Veronica Cartwright in a image that has since been meme-ified into ubiquity.

Kaufman ups the level of the basic competence of the unfortunate protagonists. The central character of Elizabeth Driscoll (played by Brooke Adams) is a research scientist with an interest in botany who notices the strange plants growing around San Francisco right at the start of the film. Matthew Bennell (played by Donald Sutherland) is a senior person in the Department of Health and well positioned to make the right calls about a public emergency. Dr. David Kibner (an un-Spocked Leonard Nimoy) is a celebrity psychiatrist who when we meet him has already noticed a sudden wave of people with an apparent delusion that their spouses aren’t their spouses — the mayor is also one of his patients and he has his private number. Jack Bellicec as an aspiring poet is less well equipped for an alien invasion (played by a Jeff Goldblum who is so young that it is adorable) but his mud-bath business owning wife Nancy (played by Veronica Cartwright) is literally genre-savvy. She engages in banter with a customer reading Immanuel Velikovsky’s pseudoscientific Worlds in Collision with a recommendation that he read Olaf Stapledon’s Star Maker* instead.

However, despite the group’s combined qualities to better cope with an invasion of pod-people the film slowly reveals that none of them ever had a chance. While we see events from the protagonist’s eyes (initially Brooke Adams but later more centred on Donald Sutherland) which creates an impression that things have only just started, it quickly becomes clear that in reality the invasion is almost complete by the time that it starts to become obvious. A substantial hint is given that the invasion has already progressed to far by a delightful cameo by Kevin McCarthy who played the lead in the original film and who reprises the character’s wild and panicked warnings from near the end of the original.

Where the film works less well is that alienating paranoia intrinsic to all the versions of Body Snatchers, is here detached from wider themes. I’m not saying that tapping into fears of communism or sexuality makes for better films just that the core quality of the film feels a little under-developed. There is a hint of a feminist aspect, in that we see two women desperately trying to explain to healthcare professionals that there is something very wrong with their husbands and being patronised and talked down to. Leonard Nimoy’s psychiatrist is given a duel role of expounding the need for rational explanations and later (as a pod person) explaining how there is now no need for either love or hate. However, the film doesn’t develop those themes deeply.

There is though something weird and fun about the combination of Sutherland, Nimoy and Goldblum in the same film. All three have had careers in which they play odd and often cerebral men but in such different circumstances that it is almost dislocating that their careers overlap here. Goldblum is recognisably Goldblum but devoid of some of the more pronounced Goldblum mannerism. There is a point in the film where Veronica Cartwright discovers the only partly formed pod-person duplicate of her husband and it is described as a copy of him but lacking much of the detail and it is an oddly apt description of the Goldblum in the film, like he is the pod-person version of Ian Malcolm. He also is given lines about alien invasions that serve as unintended dramatic irony given his later appearance in Independence Day.

I remember seeing this film on television and it both scaring and horrifying me. While I have seen the original many times, this was only the second time I have seen it. Noticeably, the gory and disturbing visual effects have not aged well. The shocking reveal of the malformed dog-human pod person created from the sleeping busker gave me nightmares (aided by a dread of going to sleep straight after being allowed to stay up late to watch it) — sadly now the man-faced dog is more funny than horrible. However, the unsettling sound track and the creeping sense that nobody can be trusted still unnerves.

The aliens have no agenda beyond existing. They don’t hate humanity and it isn’t clear the extent to which they genuinely feel continuity with their past selves or a simply alien beings pretending to be their human counterpart. The multiple questions about identity and how we might tie it to persistence of memory (which the pod-people have) is not explored but mainly because of the films core premise: everything is already too late by the time the humans start fighting back. We are seeing the final days of a war that humanity believe is just the initial attack.

Well worth rewatching if only for some excellent performances by the five leads. The call backs to the original (including Don Siegel as a taxi-driver) and the science-fiction references all add to the flavour of a film that feels like the director gathered characters together for an ensemble drama about middle-class lives and loves in 1970’s San Francisco but instead threw an alien invasion at them.

Banjo dog-man deserves their own sequel though — the story of an accidental hybrid between a busker and his dog by a confused alien pod, as it wanders through post-alien invasion California.

*[Which I’ve never read and I really should]

How to duplicate people

As a trope of science fiction there is a gulf between the fantastical idea of ‘clones’ and the mundane reality of the actual science of cloning. As of yet, actual human cloning has not taken place but primates have been succesfully cloned, specifically two crab-eating macaques called Zhong Zhong and Hua Hua. Part of the gulf in concept is illustrated by the commercial application of cloning techniques to pets. While cats and dogs can be cloned to create a genetically close animal to an existing pet, basic aspects of a cat or dogs identity including their pattern of colouring ae not solely determined by their genes. A cloned pet is not going to be identical, even at a superficial level.

So while the term ‘clone’ is what is used, actual cloning does not get at the concept which is more about duplication or near duplication. Creating another copy of a person is the essence of the science-fiction concept. Duplication of genes is just a handy hook on to which the idea can be hung. Practically we have always known that monozygotic twins are not literally identical even at a superficial level and certainly not at the level of character or personality.

So plot wise how do people get duplicated?

  • Biological cloning. As discussed above this intrinsically doesn’t work because genes are only part of the picture. However, with enough hand waving and magic technology examples like the clone-troopers from Star Wars add in speeded up growth and education to create lots of near identical people. The horror of the Star Wars clones (never really explored in terms of the appalling aspects of the idea) is not creating duplicates of people but the idea of mass-manufacturing people. There is a under-explored view of industrialisation, as well as the dehumanisation of the military’s need for essentially fungible people to serve.
  • Teleportation. Typically this is more of an unwanted side-effect of the teleporter-as-fax-machine concept. With the transmit-recreate model of teleportation there is a side-effect of possible exact duplicates being created, resulting in awkward questions of identity for Commander Riker or Kamala in Think Like a Dinosaur. There’s a fascinating bit of logical implication here that results in two quite different science fiction tropes being intimately connected. Any duplication process that can create a new version of a person (including their personality and memories as well as their body) implies a method of teleportation (transmit the information to a remote location and recreate the person). Any method of teleportation that works by capturing a person as a set of information likewise implies a method of duplicating people.
  • Print people. Mur Lafferty’s Six Wakes, imagines a future where biological structures (including functioning brains) can be essentially printed by a kind of 3D printer that uses a stock substance. Taking a step away, and thinking about duplicating a person, then all the bits of a brain need to be there but it hardly matters if the actual cells contain the same cellular structure or genes just so long as they work the same way. Put another away, the resolution of the copy does not need to be so fine as to match genetics. Indeed genetics may actually be unhelpful.
  • Robot people. When we think about it, if we want to duplicate ourselves (because we have become mad with power or seek immortality or so we can go to work & go to the movies at the same time) what we actually want is a being that thinks like us and looks like us. Does it matter if actually are duplicate is some sort of silicone layer over a titanium frame? Not at all, indeed that may even be a bonus. Biology is over-rated.
  • Non-embodied duplicates. Of course to create a robot version of a person implies that it is possible to create a digital simulation of a person’s mind and personality. In that circumstance, do you even need a physical duplicate! A virtual reality duplicate may be more than good enough.
  • Mirror-universe twin. Let’s get back to physically identical duplicates. If parallel universes exist then parallel versions of you exist. Here the not-quite-the-same aspects are a plot-feature. Evil versions of you sporting a goatee but still somehow like you are likely to crop up as soon as you start hopping around universes.
  • Time-travel. Technically this is just the one version of you until you cause the time-line to splinter at which point the extra version becomes a parallel-universe twin. Even so, time travel affords a way of having more than one you in place at the same time with a simple (if mind bending) explanation of time travel.
  • Pigeon-hole principle. If you have a universe that is big enough (e.g. infinite) and which has enough people in it (e.g. effectively infinite) then the number of combinations of possible features of a person ends up being less than the number of people. In that case, there will be some people who are just exactly the same for NO REASON AT ALL other than the universe’s lack of imagination.
  • Reincarnation. Actual reincarnation beliefs are focused on the rebirth of an individual soul, although accounts may point to shared memories between the past and present versions. Fictional reincarnations provide a fantastical way for a person to be a duplicate of a long dead double. This is invariably bad news and tied up with all sorts of questions of destiny.
  • Cosmic coincidence. This is effectively the same as the pigeon-hole principle but only assumes the two people happen to look exactly alike and does not require the same personality. The coincidence of looks results in a natural doppelgänger and leads to Prisoner of Zenda like shenanigans. You can’t make this just happen though (unless you use a technique above) so it doesn’t really count as a way of duplicating somebody.
  • Surgery and hypnosis. We are now sailing into soap opera plot twists. Maybe X just looked a bit like Y and then an evil mastermind used cosmetic surgery and mind control to make them look more like Y and convince them that they are Y!
  • Just bluff. In 1854 Roger Tichborne, heir to the baronetcy of Tichborne, went missing while travelling in South America. Believed to have drowned in a shipwreck, his mother nonetheless never gave up hope. In 1865 a bankrupt butcher from the inland town of Wagga-Wagga in Australia was encouraged by a lawyer to claim that he was, in fact, the missing Roger Tichborne. Thus began the long running saga of the Tichborne Claimant. Facially only vaguely similar and otherwise quite different looking, the question remains open whether this was a lost person found or a very blatant attempt to create a second Roger Tichborne simply by sheer assertion.

A Tube Map of SF&F Genres

As with any London Tube style map, distance on the map has no connection with distance in reality. Position is about how to make everything fit. I feel like it needs more stops on the big pink Fantasy circle line. Green stops allow you to change services to mainstream rail lines. Purple stops allow you to change to the horror tram services.

There is a foot tunnel between Cyber Punk and Steam Punk.

How to fly

In the previous entry in this very irregular series of how to fictionally do a thing, I suggested that invisibility was one of the oldest of these fantastical ideas. It was only afterwards that it occurred to me that flight was just as old and just as fantastical. After all the myth of Icarus is far more famous than Plato’s Ring of Gyges, if we are talking about Ancient Greek sources. The difference is that we’ve stopped thinking of flight as being fantastical and think of it as more of a chore involving cramped seats and humiliating security checks.

Flight is still fantastical though. The superhero genre in particular indulges in essentially magical flight for a plethora of superheroes but we also have Harry Potter’s broomsticks and a in science fiction a host of machines that just casually hover about without the aid of great big blades chopping the air. So this is how to get airborne.

  • Be lighter than air. Proven technology! Anything less dense than air will be buoyant in air and float upwards. How to do that?
    • Use hot air and have a hot air balloon (or dirigible).
    • Use a gas that is lighter than air such as helium or burst-into-flames gas aka hydrogen.
    • Have some super light but amazingly rigid material contain a space that is tautologically full of vacuum.
    • You know that thing that Ant Man does where he goes really big rather than really small? If we assume he stays the same mass then his overall density should drop and he should float.*
    • Somehow make all the air really heavy so you float. I suspect this might also stop everybody’s lungs from working properly so you die. I suspect all I’ve done is invent swimming in water.
  • Push the air around really fast.
    • One way is to go really fast in general but have fixed wings that push the air down i.e. a plane.
    • Or do exactly the same thing but use Bernoulli’s principle to explain why it helps you fly.
    • Use a massive rocket to explode gases and push those out downwards. If you are feeling scatological do this using a superhero’s bottom an intestinal gas.
    • Have articulated wings beat the air in a pattern that generates lift, like a bird and/or be a bird. You may need hollow bones.
    • Have big blades that spin around really fast and push the air downwards to generate lift i.e. a helicopter.
    • Use a mix of all these things for a really complex flying machine.
  • Mess with gravity. OK but what if you don’t have to go downwards?
    • Anti-gravity. Magnetic forces attract and repel, so just figure out a way to make gravity repel. Ideally have it like a switch you can turn on or off. Yes, this does imply you can make some sort of perpetual motion machine but we can let the accountants take care of that.
    • Gravity blocker aka Cavorite. Slightly different concept to anti-gravity. Here you negate or shield an object from the force of gravity. There still needs to be some force to move the object upwards but only enough to deal with inertia.
    • Distort space-time geometries. See my previous discussion of faster than light travel.
  • Be in space. Either get far enough away from any planetary masses or be in orbit around them and you can float about as much as you like. Perhaps more than you like if your bones start suffering from it.
  • Use some other force. Gravity sucks. It’s seriously weak. A fridge magnet can defy the combined gravity of the mass of a planet.
    • Some sort of hand wave about electro-magnetism.
    • Less of a hand wave about superconducting materials and electro-magnetism.
    • Definitely magnets somehow.
    • The Strong Force is over a hundred times stronger than electromagnetism! So that’s very strong. Surely that can help! [reads fine print: “At the range of 10−15 m “. Hmm OK maybe not a viable distance.]
    • The Weak Force doesn’t sound so great and also I have really no idea what it does and the explanations seriously don’t help. The good news is very few people know enough about it to contradict any vague claims you might make about it. So claim that using a clever material that helps you fly because of the weak nuclear force and you will annoy some physicists but seriously, how many physicists are there in the world anyhow? Not many.
  • Magic and or psychic powers. Yes, that is a non-explanation but you can point to forces that are stronger than gravity such as love, hate, believing in one’s self, nature and rainbows.
  • Be immaterial. I think this coincides with several of the other things listed above but it deserves its own entry. If you don’t actually have any substance because you are a ghost, spirit or astral projection then there is nothing stopping you flying. Simple.
  • Be virtual. If you exist in a virtual environment as a computer simulation then gravity is also simulated. By hacking the system or somehow by becoming “The One” you should be able to fly. Hints that you might be “The One” is if your name is an anagram of “One”. If Brian Eno starts flying unaided that may indicate we are all in a simulation.
  • Take lots of drugs. You won’t actually fly and you should not attempt to fly.

At the end of this, I realise I don’t know what the in-universe explanation of how Superman can fly is. I get that he gets his powers from being a Kryptonian living on Earth with its yellow sun that fuels his powers but what makes him fly? Answers on a postcard please.

*[As this doesn’t happen, we have to infer that his mass changes when he gets big or small. However, if you are imagining some amazing ability to shrink or grow large then I think the density thing is actually way more interesting.

How to…make something invisible

Of all science fiction objectives, invisibility is one of the oldest and most plausible. Plato’s fable of the Ring of Gyges in The Republic used the idea of invisibility to discuss ethics. H.G.Wells added the concept to the staples of science fiction with The Invisible Man. The plausible aspect is that many things in real life (such as air) are invisible and others are transparent (such as glass) or can become effectively invisible (such as putting glass in water).

Making a person or a random object invisible is a more substantial challenge and the idea of invisibility is as much a trope of fantasy (Bilbo’s ring, Harry Potter’s cloak) as science fiction (Romulan cloaking device).

Let’s consider the ways:

  • Darkness: stop or reduce the amount of light being reflected off you. At one level this is simply wearing dark clothes at night. At another level this is using materials and shape to reduce the amount of radio-waves from RADAR bouncing off a stealth fighter.
  • Camouflage: the second most basic idea is to match the appearance of the target (person or object) with the background.
  • True invisibility: here light passes through the target making them perfectly transparent. There are issues – specifically if you were perfectly transparent then you couldn’t see as the light wouldn’t be absorbed by your eyes. However, invisibility need not be 100% to be effective. In The Hobbit, Bilbo still casts a shadow in bright sunlight (and as we learn in Lord of the Rings, the ring wearer is visible in other ways…)*
  • Bend light around you: if light goes around you instead of through you then maybe an invisibility cloak would be possible! Talk of complex metamaterials abounds! On the other hand here’s a Canadian company doing something vaguely like it with a sheet that’s a lenticular lens: https://www.iflscience.com/technology/a-canadian-company-has-created-an-incredible-invisibility-shield/
  • Dynamic camouflage: make your front look like your background with electronics. At it’s simplest get a digital projector to project an image of what is behind you on to your front! Stepping a little further into technology that doesn’t quite exist yet, use nano-electronic materials that can detect incoming light from one direction and project it from another.
  • Neuro invisibility: maybe manipulating light is hard work. Perhaps it is easier to hack the brain. Your system of visual perception already does a lot of editing and interpolating – hack that (how? waves hands…somehow…) and your ‘eyes’ can no longer see the target object.
  • Psychic or psychological invisibility: you can’t see what your brain won’t let you see. By using magical mind control powers and suddenly nobody can see you. Beware though, this might not work against robots, dogs or bats.
  • Be very small: technically this is not invisibility but if you are very small your are very hard to see.
  • Don’t exist: if you are in some way immaterial (a ghost, a psychic projection, a being embodied in electromagnetic waves etc) then you are just naturally invisible. I guess ghosts have reverse psychic invisibility i.e. technically not there so actually invisible but people can see them because of spooky things.
  • Hide and misdirect: stage magic makes things invisible by hiding objects or getting people to look where the thing isn’t. This requires a lot of work and a controlled environment.

*[The thing about Bilbo’s shadow makes me think that the One Ring makes its user actually transparent but not 100% transparent i.e. it is a physical effect. However, most other aspects of the One Ring seem to be psychic effects, so possibly it is psychic invisibility as well and the shadow thing is a bug in how it messes with your perception.]

How far can a person travel in a day? My initial guesses

I was thinking about fantasy maps and how far people can travel. I’m guessing there’s probably excellent charts on this in some game source books but I couldn’t find a handy chart online so I made some guesses.

Feedback and correction would be welcome as these aren’t great guesses. I tried to split it into four levels of travel:

  • Saunter with breaks and distractions: the travellers are stopping off for various distractions, fights, visits to gift shops.
  • Non-distracted but not gruelling: the travellers are actively trying to get from A to B but at a reasonable pace for people who don’t want to arrive exhausted.
  • Marching/swift: The travellers are pushing themselves or on a fast service.
  • Extreme: Desperately fast or pushing the limits
Travel in a day
Saunter with breaks and distractions Non-distracted but not gruelling Marching/swift Extreme
Walking 10 km 20 km 30 km 40 km
Bicycle (good roads) 30 km 60 km 100 km
Bicycle (rougher roads) 15 km 30 km
Horse – single 30 km 60 km 100 km
Small company on horses
50 km 70 km 100 km
Large group with horses and wagons
30 km

Large sailing ship
220 km 450 km 660 km
Ox cart
10 km

Coach (with regular horse changes)
100 km

Train (Victorian – variable time spent on train) 200 km 600 km 1000 km

OK, so kilometres are annoying but I like them. Here’s the numbers above converted into miles. Looking at the miles I think I’ve been underestimating.


Saunter with breaks and distractions Non-distracted but not gruelling Marching/swift Extreme
Walking 6 miles 12 miles 19 miles 25 miles
Bicycle (good roads) 19 miles 37 miles 62 miles
Bicycle (rougher roads) 9 miles 19 miles

Horse – single 19 miles 37 miles 62 miles
Small company on horses
31 miles 44 miles 62 miles
Large group with horses and wagons
19 miles

Large sailing ship
137 miles 280 miles 410 miles
Ox cart
6 miles

Coach (with regular horse changes)
62 miles

Train (Victorian – variable time spent on train) 124 miles 373 miles 622 miles 932 miles