Newton's Laws in Science Fiction TV and Movies

Chad notes, in response to PZ's rather absurd assertion that biology is the only Dumped Upon science, and that physics is so well treated in movies and TV, that "Most of the SF movies I see are lucky if they can get Newton's Laws right, let alone any of the finer points of astrophysics."

Indeed, this was the topic of one of the two talks I gave at Hypericon a couple of weeks ago.

Let me try to explain one aspect of this: specifically, the motion of space fighters.

Don't get me wrong. Star Wars is a great movie, one of my all-time favorites. It's even still a pretty good movie if Han doesn't shoot first, even though that's an absurd change on so many levels. But Star Wars wrecked the popular perception of how space fighters would move in space for a long time. The basic problem is, they move like airplanes.

xwing.jpg

There are two things about an airplane's motion that the Star Wars fighters do, even though they shouldn't have to. First, an airplane is always moving in the direction it is pointing. if you know Newton's laws, you will ask, "moving relative to what?" Well, relative to the air that it's moving through, of course! If they didn't, they'd fall out of the sky, for they are aerodynamically designed to fly by pushing up off of the air. But there's no air in space; the density of gas even in high earth orbit is lower than the density of gas in the hardest vacuum we can create in the lab on Earth. If your space fighter only has reaction engines that point in one direction (as is the case, at least, with the X-wing fighters of Star Wars), then they have to point in the direction that they are accelerating... but not in the direction they are moving. All those Y-wing pilots who died attacking the Death Star because they had TIE fighters on their tails whom they couldn't shake? A tragedy of misunderstood physics. They didn't have to loop around to fire at the TIE fighters, the way airplanes do; they could have just turned around in place!

The second thing Star Wars routinely gets wrong is that fighters in space do not have to bank. When an airplane turns, it banks. Think about being in a car going quickly around a curve. You're more likely to maintain control of your car if the road is banked. Look at a high-speed racetrack sometime, and you'll notice that the curves are banked. What's going on is that to turn to the left, a vehicle needs some acceleration pointing to the left of its current direction of motion. With a car on a flat road, that acceleration is provided entirely by friction between the road and the tires. On a banked road, some of that acceleration is now provided by the road pushing up on the car. Similarly, with an airplane, the main force of the air on the plane is the air pushing up on the wings, generating lift. If an airplane wants to turn left, it banks so that the bottom of its wings are pointing to the right. This, combined (crucially!) with the plane's motion, gives it some acceleration to the left, allowing it to turn.

In space, there is no air to bank off of! Once again, things work differently. First of all, these space fighters are all (approximately) in freefall. They're either in deep space, or they're in orbit about a planet, so there is (effectively) no gravity to fight. Second, without air, they can't bank off of it. Want to go in a different direction? Point your engines in the direction such that the acceleration applied to your current velocity vector (relative to whatever you're measuring your velocity relative to) will give you a velocity in the direction you want.

What would this look like? It would look weird to those of us who are used to things flying like airplanes or, alas, flying like the fighters in the worlds most popular space movie epics (where the space fighters fly like airplanes). But sometimes it's done right. The new Battlestar Galactica series tends to do it pretty well. Before that, though, back in the early-mid 1990's, the TV show Babylon 5 (still my favorite) explicitly had space fighters obeying Newton's laws. It was a rare gem to see, and it warmed my physics nerd heart. (I'm the kind of guy who gets a warm and fuzzy feeling to hear the pilot of a science fiction fighter say "coordinating vectors for grapple." Look! Technobabble that actually means something and makes sense!)

The very first episode of the series (after the pilot) was "Midnight on the Firing Line," and it showed a space combat between a group of raiders and a squadron of Starfuries (which are well designed space fighters; whereas X-wings look cool, Starfuries are cool and look like they were designed for Newtons-laws-obeying space!). At one point, Commander Sinclair has a raider (in a little potato chip ship) on his tail:

b51.jpg

If he was in a Y-wing, I guess he'd just have to die. (Indeed, he does take some fire— you can see it happening there— but he was hoping for a surrender.) Instead, though, what does he do?

b52.jpg

In the picture above, you see him just starting to turn around. The asymmetric firing of the engines makes sense given the direction he wants to turn. Does he have to bank or loop around or anything like that? No. He just points in the other direction. His fighter continues to move in the same direction relative to the larger ship as it had been, but now he's got his guns pointing in the right direction:

b53.jpg

much to the dismay of the raider:

b54.jpg

Here, also, you can see that Sinclair is accelerating away from the exploding raider ship. Probably not a bad idea; there will be debris coming away from it. Also, a line he said before turning around suggested that he was slowing himself down relative to the raider, so it was probably approaching him at this point; he'll want to get away to avoid a collision.

There are other great tidbits of space fighters qualitatively getting Newton's Laws right in that scene, and in other scenes from Babylon 5. Indeed, the fact that the Raiders have ships that look like flying wings is explained; Sinclair says that they are designed for both space and atmosphere, and as such the wings are good vulnerable points to shoot for.

More often, though, when you see something with ships flying about in space, not only do they make sound (which happens even in B5), but they fly like airplanes. Very few people realize the degree to which this is a violation of Newton's Laws. Kudos to Babylon 5 for trying to get it right.

33 responses so far

  • Qoheleth says:

    Ships may not need to bank in order to turn, but one could still make the argument that pilots do so for their own comfort: I imagine that 3 g's pressing you down into your seat is somewhat less distressing than 3 g's pushing you to one side of the cockpit.

  • I wish script writers would learn a bit of orbital mechanics. I remember one glaring error in Star Trek TNG where they wanted to raise periapsis of an asteroid (mistakenly but understandably called perigee in the show) so they applied delta V there. Sorry guys, it just don�t work that way. The most efficient place to apply your delta V to change an orbital altitude is on the opposite side. To change perigee, fire your thrusters at apogee.

  • bigTom says:

    Salad: But if they followed the laws of oribital mech they wouldn't need to use such huge amounts of power just to move around, and their orbits wouldn't automatically decay in 24hours...
    What bothers me more are space explosions:
    First there is gas being released into a vacuum. Wouldn't look at all like the stock footage of airburst explosions they always use.
    Then it became fashionable to have the expanding ring shock-wave, always viewed at an angle so we see an expanding ellipse. Looks cool, but unless interacting with a plane of material wrong.
    Lastly there is the shock wave advancing. Always simulated by a series of timed explosions, so that it moves in steps arrrgh!

  • Jeff says:

    One glaring error that comes to mind in Empire Strikes back, occurs when the Falcon is being chased through the asteroid belt. At least one asteroid changes direction for no apparent reason. And many asteroids were moving in all sorts of directions. Wouldn't they have to be traveling mostly in the same direction and velocity, otherwise there wouldn't be an asteroid belt?

  • Vorpal Blade says:

    It always bugged me that space fighter guns only fired forward. It would make more sense to have guns that fired at where the enemy was, without requiring changing trajectory, leaving trajectory changes only as evasive maneuvers.

  • Rob Knop says:

    Ships may not need to bank in order to turn, but one could still make the argument that pilots do so for their own comfort: I imagine that 3 g's pressing you down into your seat is somewhat less distressing than 3 g's pushing you to one side of the cockpit.
    Well, sure. However, that would still not result in a bank. A bank will only work if you have air to push off of.
    To accelerate, the ship has either to fire its jets in the right direction, or orient itself so its jets are pointing in the right direction (i.e. opposite the direction of accelerate), and fire. In no event will they fly like airplanes.
    Re: guns firing forward, if they aren't firing homing or tracking rounds, and if they can only see in one direction, it makes sense to shoot in the direction you can see (with perhaps a small range of motion). If you can quickly reorient your fighter, there's no need to be able to fire in any direction. Again, the problem is in Star Wars that they have to be pointing the way they are moving-- a concept that doesn't even make sense in space combat. In B5, they can turn their ship (and thus their guns) in any direction they want at any moment.
    -Rob

  • Anonymous says:

    when you see something with ships flying about in space, not only do they make sound

    I have never had the urge to study up the "technical manuals" of the Star Trek universe where they supposedly explain most of the oddities. But I seem to remember someone saying that interactions between fields (for example warp and shield fields) and ship hulls are the default explanation for 'vacuum' noises. (Assuming the movie camera "observer" is looking on from a ship, I guess.)
    That would go for the Star Wars universe too, I guess. Perhaps field interactions 'explains' some of the ship flight dynamics as well. I don't think Star War X-vings can be assumed to have reaction engines, at least as long as no character has come out and said so. Light-emitting engine nacelles in Star Trek can be anything up and beyond warp nacelles...

  • Brandon says:

    It looks like the X-Wing has four rear-mounted rockets. Presumably, to turn clockwise (relative to somebody looking down from above the ship) it would deactivate the two right rockets. But wouldn't that, in addition to making the ship turn clockwise, make the ship veer to the right? I'd think, to change the direction you're facing without changing the direction of movement, each of the four rockets would need a corresponding retrorocket.

  • Rob Knop says:

    Brandon -- if they didn't fly like airplanes, then, yes. (Like the Starfuries have.)
    However, since they fly like airplanes (causing some of the authors in the novelizations to use terms like "etheric rudder" -- I guess they're thinking along the same lines as Torbjorn), they can just bank off of... whatever it is they're banking off of... to turn.
    Some real spacecraft, like the Hubble Space Telescope, use internal gyroscopes to reorient themselves. This sort of thing would work for space fighters as well. Have a few bigass gyroscopes spinning inside, and just turn them relative to your hull to get your hull to rotate relative to the outside world.
    -Rob

  • Killjoy Woz Here says:

    Hey guys, you've missed the point: Star Wars isn't a space movie -- it's a 1950s adventure movie with Second World War themes in non-period costume and the little plastic spaceships are a hybrid of Spitfires and Mosquitos in fancy dress -- can't you see that the attack on the Death Star is a re-hash of 633 Squadron? So they've got to work like WW2 fighters or fighter bombers to make it work.
    Next we'll have complaints about "A Wookie Wouldn't Say That". Sorry folk, Star Trek, Star Wars, they're not real.
    Now I must find out what's happened this week in Ambridge (ha! that'll fool non-UK readers!).

  • Rob Knop says:

    Star Wars isn't a 1950s adventure movie, it's a high fantasy movie with universal mythic themes.
    You've got the old wizard, the unknown commoner who has a deep inheritance, you have the evil wizard overseeing the ruthless kingdom, you've got the full-on Campbellian Hero Journey, etc.
    -Rob

  • skwirlinator says:

    There is a Babylon Five Game(I Found Her) out that has you trying to maneuver a starfury in space. It's not that easy and plays with your senses. But I enjoyed it.
    Something that gets me is how every ship and station and planet always meets up in the upright position.
    I took Google earth and flipped the north and south poles then started it rotating and went and got my kids. I asked them if they had ever seen a planet like that. Nobody saw it as Earth until I flipped the north pole back where it belonged. It was totally unrecognizable to them yet you could still see every continent clearly. You can try this with your friends or co-workers and see if the can recognize it.
    Just tell them its a new feature of G E. that shows planets.
    See if anyone can tell. It's amazing.
    I also read recently that the Sol system is part of a dwarf galaxy that was swallowed by the milky way. Our planetary plane is out of alignment with the galactic spiral arms. We are sideways.
    On propulsion, There would have to be vectored thrusters at all axis of the ships in space. Braking would have to be done by reversing the main thrusters and retro firing to overcome the momentum. Every maneuvering thrust would need a counter thrust to brake the momentum. The calculations would be supercomputing tasks and the fuel would be horrendous. Every maneuver would have to be recalculated to compensate for the reduced mass of expending the fuel used to make the prior maneuver. There would be such a tremendous heat generated by the computers that the occupant would fry, thus reducing the mass more causing more calculations and more heat. The heat would change the properties of the surrounding space causing quantum entanglement and changing the properties of the protons surrounding the craft. This would cause the craft to wink out of existence and phase through the frost boundry of the temple of arasas keeping small dogs with rabbit faces from procreating.
    Its not a pretty picture - I tell ya!

  • "Star Wars isn't a 1950s adventure movie, it's a high fantasy movie with universal mythic themes.
    You've got the old wizard, the unknown commoner who has a deep inheritance, you have the evil wizard overseeing the ruthless kingdom, you've got the full-on Campbellian Hero Journey, etc."
    Stop! You're both right! Lucas used Campbell's The Hero with a Thousand Faces as a major source, but he also made nostalgic references to old-timey sci-fi comic books, and he had his special effects guys watch WWII planes in action to make the space battles.

  • Neil says:

    Now I must find out what's happened this week in Ambridge (ha! that'll fool non-UK readers!).

    Peter Donaldson on radio:

    ...David discovers evidence of reverse temporal engineering in Brian Aldridge's past...

    (H2G2, Fit the 22nd)

  • David Harmon says:

    I remember at the time someone was telling me Star Wars was an Arthurian rehash, but I never managed to match up enough plot points. Let alone travesties like Step'n'Fetchit/Jar Jar Binks....
    Some of the airplane-like behavior could be handwaved away as follows: the crafts' major insystem drive might work by exerting drag/lift against changes of gravitational potential, with a limited range of vectors determined by the orientation of the engine itself, the gravitational equipotential surface, or some combination. But that would probably bring in all sorts of other constraints that the SW crew never considered! Moral of the story: Sort out your physics before your film.... 😉

  • Rob Knop says:

    I think the only real justification for Star Wars fighters flying like airplanes is that "they wanted it to look that way."
    Trying to back it out into some way of reverse-engineering real physics is... well, it's gonna fail. I suppose you could come up with some sort of exotic drive whereby it would make sense, using terms like "etheric rudder," but in the end it's clear that you're scrambling and trying to cover for stuff that was just wrong. So, let's just sit back and enjoy it as a movie, but use it as an example of a mistake when we're talking about what's done wrong.
    I remember at the time someone was telling me Star Wars was an Arthurian rehash
    Part of why Star Wars is so popular is that it hooked into a whole bunch of archetypes and common stores. It was explicitly modeled after the Joseph Campbell stuff. I've seen it described as a martial arts movie -- and that case can be made. It's clearly on some levels a science fiction movie. It's clearly on some levels a 1950's adventure movie. And so on and so forth. It's a great movie because so many of us can find so much fun stuff to like in it, and because it reminds us of so many different things. (Indeed it probably all goes back to the Campbell.)
    Too bad the magic was gone in episodes I and II.
    -Rob

  • Mark Whybird says:

    Here's a video from a Babylon 5 game (possibly the one that skwirlinator mentioned above):
    http://www.youtube.com/watch?v=uNzQK5ntfBw
    There are only two points in this clip, at about 30 and 36 seconds) where it is reasonably clear to me that the physics are non-aircraft in nature.

  • Mark Whybird says:

    ... and in this sequence of Babylon 5 footage:
    http://www.youtube.com/watch?v=W0y0BUyqPTw
    a very neat example of the Newtonian turn-and-fire idea is visible at about times 4:02 to 4:07, and a less blatant (but still good) one at about 1:54.
    There is also an instance of air banking, but it does seem to be in an atmosphere.
    (I've also linked to this post in my own little blog: http://blog.whybird.net/post/4798246)

  • Dunc says:

    I suppose you could come up with some sort of exotic drive whereby it would make sense, using terms like "etheric rudder," but in the end it's clear that you're scrambling and trying to cover for stuff that was just wrong.
    You could try arguing that they use sophisticated avionics to sort-of replicate the physics of atmospheric flight because true Newtonian physics makes piloting a bitch. It's hard enough to maintain situational awareness in space combat without having to calculate your own vectors... Of course, this would present a major tactical advantage to anyone who could fly using Newtonian physics, so it's a bit lame...

  • mark heath says:

    tip of the hat to the Firefly series (not the movie): space is without sound, and the ships move along in an eerie quiet.

  • Panya says:

    ... Star Wars was an Arthurian rehash ...
    O.o Wuh? *headdesks repeatedly* Star Wars is an Arthurian rehash in the sole sense that they are both at this time developments of that Hero's Journey Rob was talking about. Anyway, there's a gender-size plothole in that idea -- there aren't enough women! The Matter of Britain has at least three major female figures in every variation so far, and usually more.

  • MikeB says:

    It seems that the You Tube clip of the cancelled B5 game has some info about another (freeware) B5 game, called I found her - have a look here http://ifh.firstones.com/
    I'll certainly try it out - although if they are using Newtonian Physics in the game its going to be a bit like playing the old 'Descent' game - which was very disorientating!

  • Supernova says:

    @skwirlinator: check out Bad Astronomy for the real scoop on that "Sol system is from another galaxy" silliness:
    Is the Sun from another galaxy?
    Alen Sun followup
    Alien Sun, final(?) comment

  • Star Wars is VERY clearly Space Opera.
    SPACE OPERA: battles between planets and stars, although not quite as purely fun as "Ftfth Element."
    Brian W. Aldiss, in his anthology "Space Opera" [Garden City NY: Doubleday, 1974] identifies various key indicators of "Space Opera" as (if I may interpolate from his delightful introduction):
    (1) Style and Mood staunchly traditional
    (2) Hitherto unknown places to explore
    (3) Continuity between Past and Future
    (4) Tremendous sphere of space/time
    (5) A pinch of reality inflated with melodrama
    (6) A seasoning of screwy ideas
    (7) Heady escapist stuff
    (8) Charging on with little regard for logic or literacy
    (9) Often throwing off great images, excitements, aspirations
    (10) The Earth should be in peril
    (11) There must be a quest
    (12) There must be a man to match the mighty hour
    (13) That man must confront aliens and exotic creatures
    (14) Space must flow past the ports like wine from a pitcher
    (15) Blood must run down the palace steps
    (16) Ships must launch out into the louring dark
    (17) There must be a woman fairer than the skies
    (18) There must be a villain darker than a Black Hole
    (19) All must come right in the end
    (20) The future in space, seen mistily through the eyes of yesterday
    Well, not all these indicators are valid even for each of the stories he's assembled, but his list is indicative.
    Isaac Asimov, Leigh Brackett, Ray Bradbury, Edgar Rice Burroughs, John W. Campbell, Arthur C. Clarke, Edmond Hamilton, Robert A. Heinlein, Robert Sheckley, E. E. "Doc" Smith, Olaf Stapledon, Jack Vance, H. G. Wells... many fine writers have penned timeless Space Opera.
    Before we go to it, let me disagree with Aldiss' mournful
    "Nowadays--rather like grand opera--it is considered to be in decline." Well, not any more. The subgenre has been invigorated by Iain Banks, David Brin, Gregory Benford, Kurt Vonnegut, and Vernor Vinge among others.
    There are several recent fine anthologies of Space Opera... Google for them!

  • Fred Ross says:

    Personally, I think individual fighters in space combat are ludicrous, whatever physics you care to impose on them.
    Instead, I envision space combat being much more like a game of three dimensional chess, blindfolded. You have some number of ships and long distances, and basically you lay down a series of attacks which won't take effect for minutes to days, and do so in such a way that the opponent ends up maneuvering into the attack.
    Over this range you don't work by sight, nor by little boxes running around your screen. At this scale, even keeping all the events you need synchronized is problematic, as tiny shifts may change a hit into a miss over long distances.
    On the other hand, while this would make a great book, it would make for really lousy watching on the screen.

  • Rob Knop says:

    Personally, I think individual fighters in space combat are ludicrous, whatever physics you care to impose on them.
    That will depend entirely on the quality of your AI, the nature of your weapons systems, the nature of your counter-weapons systems, etc. Who knows.
    The thing is, FTL drives in science fiction do not bother me; starfighters getting Newton's Laws wrong does. In one case, it's new physics, rubber physics, or even fantasy. In another case, it's a violation of verisimilitude because things are just moving wrong I'd categorize space fighters in the same category— although, not really knowing what "realistic" space weapons would look like, it's hard for me to say definitively that a space fighter doesn't make sense. (Something with a small radar signature carrying a nuke in close? Might be useful!).
    -Rob

  • Peter Erwin says:

    ... It was explicitly modeled after the Joseph Campbell stuff.
    Jonathan Vos Post has a good point: Star Wars largely modeled after old Space Opera.
    This article in Salon argues that the Joseph Campbell name-checking came after the fact: Lucas only started referencing Campbell several years after SW was released, perhaps because "It invokes ancient, epic mythology" seems more elevated and classy than "It's a fun movie based on classic genre stuff I loved."
    Of course, there are mutliple influences on SW. One of the most obvious, and one which Lucas has acknowledged, is Kurosawa's movie The Hidden Fortress.

  • rpsms says:

    I clearly recall Lucas back in the 70s quoting a few specific sources:
    Tora Tora Tora
    Kurosawa
    Buck Rogers
    Erol Fynn
    Dune
    Despite his recent re-writing of history ("lies"), I recall him specifically saying that the movie was conceived as a single movie, but used the "serials" style and false-history motif set-up a la "Dune" and "Lord of the Rings"
    ****
    A video game that simulates newtonian spaceflight is Independance War. I played the second one (Edge of Chaos)

  • Dean says:

    "I also read recently that the Sol system is part of a dwarf galaxy that was swallowed by the milky way. Our planetary plane is out of alignment with the galactic spiral arms. We are sideways."
    Phil Plait has pretty much debunked this on Bad Astronomy here: http://www.badastronomy.com/bablog/2007/06/27/is-the-sun-from-another-galaxy/

  • JScarry says:

    Speaking as a pilot, we are taught that lift is caused by Bernoulli forces on the cambered wing top. A bank is caused changing direction of the lift. That's why you need to use rudder pressure to keep the airplane in the same plane, otherwise you slip or skid in the turn. I don't recall ever reading that banking off of the air was a factor. Is that well established in physics or are you guessing that is how it works?

  • Rob Knop says:

    It's basically the same thing.
    The whole Bernoulli effect thing is often mis-stated; I should probably write a whole blog entry about that.
    Ultimately, planes fly because the motion of the air around the wings ends up with a stream of air pointing somewhat downward. The momentum of that air downward is offset by the momentum of the plane upward-- this is what gives the lift force. So, in a sense, the plane is pushing up off of the air.
    Turning the direction of the lift is exactly what I mean when I'm talking about banking off of the air.
    -Rob

  • Justin Moretti says:

    Remember this is really science-fantasy, where fighters DO behave like WW2 and all capital ships share the same sense of "up".
    You can justify it with as much physics as you like, but in the end all that it has to be is fun to watch. Let everyone know it's not how it would really work, sure, but don't labour the point to the degree where everyone calls you a killjoy.
    BTW Niven and Pournelle's "The Moat Around Murcheson's Eye" has a very good description of a Newton-faithful long-range space battle.

  • Paul says:

    People have said already: the way spaceships fly in Star Wars is the thin end of a huge wedge. As you say, it's a great film (and indeed, a pretty good series), but it is scientifically incoherent - but I don't think it was supposed to be scientifically coherent. It's high fantasy/hero myth set in a supposed futuristic setting.
    One might also take it to task for its spin on cybernetics, planetary development, evolutionary biology, theology/metaphysics, agriculture, transport technology ....