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RECOIL! Science vs. technobabble in military sci-fi

In the early 1990s, in Star Trek The Next Generation, Geordi LaForge became famous for figuring out that a quick reconfiguration of the ship’s equipment — in a way no one had ever considered before — would solve the impending crisis. Realizations along the lines of: if we reversed the polarity of the shield generators and channeled the resulting feedback into the Jefferies tubes, we can slip back in time a few seconds: just far enough to escape the enemy missiles.

The term technobabble was born. But the idea of stringing together clever sounding words to break the laws of the universe whenever convenient was old long before Geordi’s phase generators.

Twenty years earlier, for example, Jon Pertwee hated the nonsensical pseudo-science jargon in his Doctor Who scripts, notably his Doctor’s catch phrase: ‘reverse the polarity of the neutron flow’. (Of course, neutrons don’t have any charge, hence their name).

200px-Third_Doctor

The Doctor reversing the polarity of the neutron flow

Doctor Who and GeordiLaForge: these characters are powerfully popular. Somehow, talking nonsense had become an endearing eccentricity, rather than a failing of the writing team (although I felt Star Trek’s technobabble was used a little too often to get the Enterprise out of trouble).

I think the explanation for this acceptance is that with a TV show, you can see and hear the actors portraying the character. It’s much easier to believe that they are real people, to identify with them, and — crucially — trust them.

I mean, take Jon Pertwee’s time lord. He might talk nonsense about the charge on neutrons, but who could possibly fail to trust a craggy old man dressed up like a stage magician, and driving the same yellow toy car as Parsley the Lion?

But when you tell your story through the written word, winning trust and empathy from your reader is much harder. And technobabble is one aspect of storytelling where I believe readers are less forgiving than viewers.

Authors, don’t do it!

(Me included!)

I’m reading a lot of military sci-fi at the moment. I’m reading it because it helps fuel my mindset to write it.

And, let’s face it, I love reading it.

I’ve read stirring tales of great wedge-shaped fleets of spaceships crashing against each other like charging heavy cavalry squadrons, flashing pretty beam weapons at each other just before the front lines make contact, in the same way a cavalryman of the 18th century would fire his pistol. Having made shattering contact, the ships swoop into a confusing space dogfight.

A space marine with feet firmly planted on the planet’s surface raises her super-advanced combat rifle to her shoulder, and lets rip with 500 shells per second at the enemy gun emplacement she can see in her HUD.

Now, sometimes, I have problems with these descriptions. Don’t get me wrong. I don’t want lots of science and technical data in my military sci-fi. I want action, adventure, and how-do-they-going-to-get-out-of-that? But what I also don’t want are technobabble and lazy, improbable physics, because that takes me out of the story in just the same way as spelling errors and clumsy wording.

UFO attack

This is a wonderful image, but the physics is wrong in so many ways. Image (c) mik38 /Fotolia.com

When the advancing space ships close to beam weapon range, what is that exactly? What range? In the vacuum of space, why is a laser, or other beam weapon, any less effective at a distance of, say, 10,000 miles, than it is at a distance of 200 yards? There’s no atmosphere to scatter the beam in a vacuum. In fact, there is an answer: diffraction, meaning the longer the range, the wider the beam’s cross-section when it hits the target. But effective range for lasers and other directed beam weapons is much greater than some authors depict. And spacecraft cannot ever swoop around in a Star Wars style dogfight because there’s no air to redirect your momentum.

And as for the space marine letting rip with a gun that has the fire rate of a 20th century heavy machine gun on fully automatic, how can they possibly aim with all that recoil force? Even if they could aim, if they’re in heavy armor, and are firing from the shoulder, wouldn’t the recoil topple them over and pound them into the mud? It would be like pushing on the end of a lever. For that matter, where is all the ammo stored? If you look at classic HMGs, they’re typically tripod mounted with belts of ammo folded into boxes. And they aren’t normally fired at full speed because that makes them difficult to aim accurately and the ammo runs out real fast.

Recoil?

I don’t pretend to be any kind of weapons expert, but I’ve fired guns and my shoulder tells that the bigger the bang at the business end of the barrel, the harder it kicks back at me through the stock.

If you look through amazon.com reviews of military science fiction, one of the most common complaints is that the author doesn’t take account of recoil.

So when I wrote the Human Legion books, I thought I’d better follow my own advice: talk to some combat professionals and get my research in. Once I’d gotten my facts straightened out, hopefully I could feed that naturally into my military sci-fi writing without needing to dump indigestible lumps of exposition onto my readers. I’m going for believability rather than complete accuracy, and I’m prepared to bend physics a little if it serves the storytelling. But I don’t want to get the science blatantly wrong because I haven’t bothered to research it.

One of the most surprising answers I found was with railguns. I’ll explain that in more detail in my next post.

12 Comments

  1. SGT Mike says:

    I prefer the term ‘creative genius’ to ‘technobabble’!!

  2. Master Zed says:

    A few comments regarding some of your concerns:

    1) unless firing at a predictable target (something that’s not maneuvering), the practical limit for laser range (and any non-self guided projectile for that matter) is primarily based on targeting difficulties, not generally diffusion. Specifically, at 1 light second away from a target (approx 300,000 km, or a little less than the distance from the Earth to the Moon – yes, when you look at the moon, you are actually looking at where it was 1-2 seconds ago – mind blowing, right…) your laser is actually firing at where something was 2 seconds ago (1 second for its light to reach you and give you information on its position and velocity, then 1 second for your laser to reach your target point). Now, let’s consider what this means…

    I believe Apollo 10 holds the record for the highest speed attained by a manned vehicle with about 11 km/s. Which means your Earth based laser is off its mark by 22km by the time it reaches the Apollo 11 (assuming you were just visually aiming using a telescope or other purely optical rig).

    The fastest spacecraft launched from Earth was NASA’s New Horizons mission, which […] left Earth at […] (58,000 kph). This UNMANNED probe would still take around 3 months to reach Mars – not exactly scifi speeds here (in fact, not scifi at all – this is sci-fact) but we’ll press on. This translates to about 16 km/s, which means at 1 light second out it travels 32km before your laser reaches it.

    The answer? Well, have your fancy computer lead the target, right? Well, if it’s not maneuvering AT ALL, then sure, otherwise we’ve still got a problem here due to the velocities and ranges being talked about in space battles. From (https://www.space.com/24701-how-long-does-it-take-to-get-to-mars.html) we can get 2 key pieces of information:

    Let’s fire at a famous anime starship: the SDF-1 Macross from Robotech with a length of approximately 1200m. At 1 light second away, if you aim at where the middle of this length will be in 2 seconds based on the ship’s current velocity with your snazzy computer, you are still looking at firing at 2 second old data. If the ship were to accelerate or decelerate (in ANY perpendicular direction) by just 150m/s^2 (roughly 15g) (d=at^2 => 600m = a*2^2 => a = 150 m/s^2), then you would miss the target entirely; what’s worse, you wouldn’t even know that you missed until 2 seconds after you committed to the attack (1 second for the laser to reach its destination, 1 second for the results to get back to you). Also, please note that unless you have FTL sensors as part of your scifi setting, this is the physical BEST you can do. Even at just 1g (10m/s^2) of possible acceleration or deceleration, at 1 light second, your target would need to be at least 10 m/s^2 * 2 s ^ 2 = 40m => 80m across to have any chance of hitting it. Again, this is the IDEAL, meaning aiming at a sphere with matched initial velocities, etc etc. ANY deviation from this means even more complications…

    Now, let’s consider the fact that space isn’t actually a perfect vacuum, in fact, in the vicinity of Earth’s orbit, the interplanetary medium has a density of about 5 particles per cm^3 (https://en.wikipedia.org/wiki/Interplanetary_medium). What this means is that if your laser has a cross section of 2 cm^2 (a beam diameter of 8mm), then for every 1 cm of distance it travels, it’ll encounter 10 particles, which may not seem like much, but at 1 ls (300,000km) that’s 6e^10 particles, or assuming they’re all hydrogen (the lightest element) that’s 1.6735575 × 10^-27 kg * 6e^10 = 1e-16 Kg of mass your laser has to burn through…

    Now, I’ll take a moment to talk about star wars maneuvers… This “they don’t fly like planes” idea only applies to Newtonian physics. So reaction type drives (ion drives, chemicaldrives – ie rockets, thrusters, etc) – ANY setting that has FTL travel will NECESSARILY not follow these laws (since these laws preclude FTL travel) – exception for jump gate type FTL, where ships use Newtonian physics nd special external devices to travel FTL. Any ship using warp, teleportation or “caterpillar” mode of travel can easily break these rules in various ways. Further, inertial dampers and shields (common scifi tropes) can significantly alter a ship’s ability to maneuver – force fields could well allow star wars like movements, as the field interacts with magnetic fields or spatial plasma to provide resistance for drifts, etc. And adjustable inertial dampers (/enhancers) can quite literally make a ship go a different direction almost instantly. Ships that use some kind of “subspace” drive or use a singularity power source may be able to do some incredible non-Newtonian maneuvers as well, since they may be able to anchor to subspace or create directional gravity waves to “catch” space and turn abnormally…

    As for “‘reverse the polarity of the neutron flow” polarity does not have to refer to charge or magnetic properties. In fact, the term flow indicates the neutrons are traveling in a direction. If we assume the “flow” is a linear path that indicates the direction the majority of the neutrons are flowing in, then we can call that the “flow’s” positive direction of travel it’s positive “pole” and the source (or opposite) direction it’s negative “pole”, at which point, you could reverse tohe polarity of the neutron flow (perhaps by bending space, or by using gravitic waves, or who knows when it comes to sci-fi 🙂 )

    For me, at least, I just assume techno babble is a stand in for “And the engineer said a bunch of words you’ve never even imagined; and even the words you did recognize were used in a manner completely beyond your comprehension.” Kind of like listening to a doctor when they use medical terms to describe your condition – without medical training and a point of reference, he might as well have said “reverse the polarity of the neutron flow,” as both convey about the same amount of useful information…

    Anyways, there’s my two cents on these issues 🙂

    • tctaylor says:

      Anyways, there’s my two cents on these issues 🙂

      LOL. I think you’ve give the full dollar’s worth, Master Zed. And change! I’m still working through all the detail, but I have to say it seems entirely plausible. You should write articles about the physics of futuristic weaponry.

      I’m interested in your point that “the practical limit for laser range (and any non-self guided projectile for that matter) is primarily based on targeting difficulties”. Shortly after I wrote these articles, I spent a day working out calculations for my ship-based lasers for use in that setting, and came up with roughly one light-second as the maximum effective range for very high-power lasers before beam divergence rendered them ineffective. I don’t think there would be any difficulty in tracking a large target ship at that distance, but keeping the laser trained on the same precise spot long enough to burn through would be difficult unless it was a stationary target. No rolling allowed. The calculator I used is still around: https://www.laserworld.com/en/laserworld-toolbox/divergence-calculator.html

      On the other hand, I’ve seen Luke Campbell’s proposal for a Ravening Beam of Death at ProjectRho (http://www.projectrho.com/public_html/rocket/spacegunconvent.php halfway down under heading ‘Non-bomb-pumped laser’). That one’s effective up to a light minute, but we’re talking x-ray lasers here and with a kilometer diameter acceleration ring, so we’re talking a whole different level from the average sci-fi battlecruiser.

      • Master Zed says:

        The problems related to targeting are with unpredictable movements. So not targets just “coasting along” or under constant acceleration in a set and/or known direction. If the target is 100% predictable, then you can hit it with anything… You could literally “open a window” and throw a rock at the target at any range with sufficient computational power and data about the masses in the system. That’s basically what NASA does with probes currently (the probes usually have minor course correction thrusters, but there are to deal with inaccuracies in current data and supercomputer simulation limits.)

        Further, all of the following assumes non-FTL sensors and non-FTL weapons (hard scifi – all sensors are EM based). FTL sensors reduce these problems by up to half (since you’re looking at less old data) and FTL weapons likewise reduce these problems by up to half (as they reduce the time it takes to reach the target coordinates). To be precise, the “FTL Speed” of the sensors and/or weapons in question effectively reduce the ranges listed here by half the same factor (a twice light speed sensor with twice light speed weaponry would treat a 2 light second engagement like a 1 light second engagement)

        I will also allow for functionally infinite (ie, more than you could ever need) computational power since we’re basically there right now in 2019 as far as these kinds of problems are concerned (on supercomputers at least). I’m also going to permit high quality narrow AI and/or extremely sophisticated simulation/ballistic software (general AI can be allowed too, but doesn’t contribute to these problems anyways, so its moot). Basically, if the math CAN be done, I’ll assume the computers involved can do it in milliseconds or less (or a trivial amount of time). I’ll also allow for instantaneous sensor data processing at essentially perfect resolution (again, just more than could be needed – all computations are handled in milliseconds or less/are insignicant). Basically what this means is that I’m ignoring computational delays in the timing problems below to simplify the math and scenarios. A truly Hard Scifi setting should not ignore this entirely, at least look at your setting and ask if these could create significant additional issues, then account for these extra complications or provide a reason they are not factors.

        A further caveat is that I’m going to allow the attacker to have a perfect knowledge of the target ships capabilities. In a military confrontation with a well known enemy, or for police attacking a registered vessel, or if sensors are sufficiently strong to gather this data, then this holds. WITHOUT this data, there is a whole extra layer of estimation and guessing that further reduces targeting accuracy and hit chance.

        I’m also going to assume perfectly spherical ships as this greatly simplifies the math. The truth is this is the ideal configuration for a hard scifi combat ship anyways as it maximizes volume while minimizing mass and surface area (ie maximizing maneuverability, minimizing fuel costs, minimizing armor mass, etc etc.). So barring specific design considerations specific to a given setting, this is a fair assumption. It also represents the “average” case, where non-spheres may present smaller cross sections along one line of attack, but then present larger ones along others – so the sphere represents the bast case – everything else will be a little easier or harder to hit based on specific orientation at a given moment.

        Finally, I will assume all combats are occurring at relative velocities much less than 1% the speed of light and aren’t occurring near extremely large/dense masses (like suns of black holes) so that relativistic effects are still trivial enough (probably) to ignore (ie, I don’t want to have to deal with time dilation, length dilation, etc.) Any of these things complicates the problems by orders of magnitude, and make attacking an enemy ship that isn’t filling a significant percentage of your visual horizon basically impossible – even with a relatively stationary target, there may be misses simply from unpredictable space time fluctuations as gravitational eddies in the massive object warp spacetime itself.

        So, long distance (around 1 light second out) targeting is a problem because the EM radiation you are using to detect your target travels at light speed, and your weapons “projectiles” (even photons and particle beams) likewise travel at light speed (or less). Meaning the sensor data received before firing weapons is already 1 second old (1 light second means you’re looking at 1 second old light). You do NOT know where the ship IS or what it is DOING, you only where it WAS and what it WAS DOING 1 second ago.

        Ok, so we project a “simulated” virtual image of the ship forward 1 second along its current trajectory based on its observed velocity, orientation and dimensions, no biggie, right? However, this velocity data is 1 second old too, so the ship can have changed its velocity (accelerated) since then, and we have to account for that POSSIBILITY since we don’t – in fact CAN’T – know it (definition of maneuvering target), so we “guess” or estimate or average, etc. (I’ll go into more details on how this matters later.)

        Next, we have to account for the time it’ll take our “projectile” (again, this projectile can be a photon) to reach its target. Assuming a light speed weapon (laser, .99999c rail gun projectile, etc.) this will take as long as the light from the ship took to reach us. This too is 1 second (give or take, now that our target may have accelerated towards or away from us). So we project our “bubble” a bit further and expand it again… (In actuality, we’ll project and expand only once, based on total round trip time – ie, 2 seconds for a 1 light second distant target.)

        And our THIRD hurdle is that we have to wait one more second to “see” the results of our strike (the light from the hit or miss takes another second to get back to the attacker)

        The problem is that our target’s volume is only a portion of that bubble we’re talking about. If the “possibility bubble” is even just 3 times the volume of the actual ship, our guess has only a 1/3 chance of even hitting it — and no amount of clever ANYTHING can change that. We don’t know where the ship is in that bubble, we have to GUESS. Maybe can try “shotgun” like tactics and make multiple attacks in a pattern that covers alot of that bubble – but then we’re just guaranteed to miss and hit with the ratio of actual ship volume to projected volume (ie, if the ship is in 1/3 of that bubble, then a scatter approach will hit with about 1/3 of our weapons and miss with the other 2/3).

        Mass based projectiles (railguns, particle weapons, etc.) can simplify this into a 2 dimensional cross section analysis (though the ship’s area within this 2d cross section can grow or shrink as it travels towards or away from the attacker or a non-spherical ship rotates to present a smaller or larger profile, so it’s still not fully 2d – but it’s close enough that you can use this for targeting purposes) since they deliver all their energy to any point along their path of travel. Basically, if ANY PART of the path of your mass projectile intersects the actual position of the target, then you have a hit and deliver (basically) the full force of the weapon. Mass based projectiles actually have a slightly bigger “cross section” than I’ll be estimating to account for the ability of the ship to “hit” the projectile (you missed, but the miss was in the path of the ship and the ship reached the bullet before it had gone past). Except for large high velocity ships, this should be pretty minor though – but it is just one more benefit of projectiles at long range.

        Lasers on the other hand have focal lengths – and even just a few meters from those focal lengths they do significantly less to no damage – so you have to guess not just the 2 dimensional position of the ship, but the full 3 dimensional position of the ship, and any “mistake” in that guess means a miss. Since we’re now missing in 3 dimensions instead of just 2, we have a MUCH bigger problem. Just to give you an idea of the difference between the 2d and 3d problem, the CMI (http://www.claymath.org/millennium-problems/millennium-prize-problems) has made the 3dimensional 3 body problem a millennium prize (ie, providing a non-approximate solution of this kind of problem has a $1million prize attached to it – and that prize hasn’t been claimed.) 3 body problems in 2d have been solved for centuries (I think) and the 3d 3 body problem has been worked on for just as long without a solution. The additional of a laser’s focal point has the same kind of increase in difficulty. To make matters worse, you’re not aiming at the ship’s full volume, you’re aiming at the SURFACE of the ship give or take 2 meters of depth let’s say (this is kind of generous actually) – since having the focal point INSIDE the ship means the laser is actually hitting the surface of the ship before its focal point and doing little or no damage… (this give or take depends on laser technology and specific laser – but you’ll see how little this matters in the examples below)

        A Non-penetrating laser (one not powerful enough to penetrate the hull/armor almost instantly – like millisecond instantly) has even ANOTHER dimension of difficulty as it has to stay on target for a given amount of time to do meaningful damage – which means we have to account for any acceleration DURING the beam’s duration. And we CAN’T physically do that at 1 light seconds out even, we can only guess, so these are basically useless against maneuverable targets. To further render these useless, sensors in the ship’s hull could easily detect such attacks and release beam scattering clouds or initiate some basic rotational acceleration to counter the damage, Ablative armor wouldn’t even need sensors, it’d scatter the laser effectively instantly as it vaporizes and creates a gas cloud that scatters the beam, rendering it harmless. All of these mean that ANY variation from the beam’s optimal focal length is troublesome.

        As an example, imagine trying to hit an egg with a projectile – it’s not too hard, since you can hit any part of the egg and crack it! You are essentially aiming at the 2 dimensional silhouette of the egg. But now imagine you have 2 laser pointers aimed at the egg, if you see 2 dots, then it’s a miss… What this means is that you’re basically aiming at the SHELL of the egg – if the cross over point of your 2 lasers are inside the egg, then the beam hits the surface before it’s focused and you see two dots and the laser is dissipated harmlessly, if they cross in front of the shell, then the beam becomes unfocused before hitting the surface and you see two dots and again the laser is dissipated harmlessly… Now, imagine trying to do this with 2 second old data about how many dots there are and how far apart they are…

  3. Master Zed says:

    For the following examples, I’ll format the data sets as follows:

    ship description
    Range: Distance (light seconds), Maximum Acceleration (m/s²) => observable distance traveled (m)
    Radius: ship radius(m) ( ship “bubble radius”(m) )
    Projectiles: ship cross section (m²) / bubble cross section (m²) (% of bubble that has ship)
    Lasers: 3d Silhouette (m³) / bubble 3d Silhouette (m³) (% of bubble that has ship)

    I’ll do profiles for each ship at 1 light second, 0. ls, and 0.1 ls

    To calculate the “laser” chances, I’ll assume a 5m thick shell centered on the ship’s surface. You still have the miss chance of the silhouette, but now, if you hit the silhouette, you have to get the depth right as well give or take a couple of meters. So I’ll use a cylindrical volume equal to the silhouette bubble times the potential travel distance *2 (can travel that distance towards OR away, so double it for potential movement on depth axis) for total potential target table area, and a cylindrical disk = actual location silhouette area * 5m (for our approximation of focal power drop off). This is actually a simplification, since the hull is going to be a shell with curvature and thinner or thicker points, the ship will be moving in a spherical manner not cylindrical, but this should give a good enough approximation to give an appropriate FEEL for the problem at least and is MUCH easier mathematically (because I’M not a super computer…)

    Specifically the formula I’ll use is: π r² * 5 m³ / π (r+d)² * 2d m³ (where d = the maximum variation in distance based on acceleration as given by d = 1/2at²)

    The % of bubble that has ship represents your chance to score a hit with a single shot (it is a completely random chance – you are guessing and so is the enemy ship as it tries to dodge). You could also consider it the % of shots that would hit if using a shotgun approach. Either way it basically represents the % of your total damage output that is taking effect on the enemy.

    First Case: A “sluggish” target (10 m/s² acceleration capable)

    Just assuming 1G of acceleration capacity (this is a bit slow for scifi setting, but could represent a ship without inertial dampening and with crew/passengers walking about in the corridors, ie a hard scifi civilian cruise liner). Fast maneuvers may cause bumps and bruises to the crew, but basically any mishaps would be at worst equivalent to falling on Earth – if we assume corridors aren’t more than 2m by 2m square and that emergency “crash webs” are deployed along their length at 2m or so intervals during such maneuvers (we can also presume air bag like emergency padding deploys along the walls and floors as needed), then no significant injuries are likely. This is literally the SLOWEST kind of ship, anything not capable of even 1G acceleration is not really maneuverable – it could still be fast if it can maintain that acceleration constantly, but it isn’t maneuverable, its flight path is largely per-determined at launch and any deviations from that path risk serious consequences like collision with your destination or overshooting it and becoming lost in deep space. So let’s look at the “possibility bubbles” created by ships of different sizes and at different ranges with this level of maneuverability – this is the EASIEST target.

    At 1 light second range (2second delay), assuming the ability to accelerate at 1G (10 m/s²), we get d=1/2at^2 = 1/2*10*2² = 20m. This means the ship can be up to 20 meters away from its projected location in any direction.

    –Small Ship (Missile, Drone, Fighter)
    Range: 1 ls, @10 m/s² => 20 m
    Radius: 5 m / 25 m
    Projectiles: 25 m² / 625 m² (4%)
    Lasers: 125 m³ / 25000 m³ (0.5%)

    Range: 0.5 ls, @10 m/s² => 5 m
    Radius: 5 m / 10 m
    Projectiles: 25 m² / 100 m² (25%)
    Lasers: 125 m³ / 1000 m³ (12.5%)

    Range: 0.1 ls, @10 m/s² => 0.2 m
    Radius: 5 m / 5.2 m
    Projectiles: 25 m² / 27.04 m² (92.45%)
    Lasers: 125 m³ / 10.816 m³ (1155.69%)

    –Medium Ship (Millennium Falcon)
    Range: 1 ls, @10 m/s² => 20 m
    Radius: 15 m / 35 m
    Projectiles: 225 m² / 1225 m² (18.36%)
    Lasers: 1125 m³ / 49000 m³ (2.29%)

    Range: 0.5 ls, @10 m/s² => 5 m
    Radius: 15 m / 20 m
    Projectiles: 225 m² / 400 m² (56.25%)
    Lasers: 1125 m³ / 4000 m³ (28.12%)

    Range: 0.1 ls, @10 m/s² => 0.2 m
    Radius: 15 m / 15.2 m
    Projectiles: 225 m² / 231.04 m² (97.38%)
    Lasers: 1125 m³ / 92.416 m³ (1217.32%)

    –Large Ship (Aircraft Carrier)
    Range: 1 ls, @10 m/s² => 20 m
    Radius: 150 m / 170 m
    Projectiles: 22500 m² / 28900 m² (77.85%)
    Lasers: 112500 m³ / 1156000 m³ (9.73%)

    Range: 0.5 ls, @10 m/s² => 5 m
    Radius: 150 m / 155 m
    Projectiles: 22500 m² / 24025 m² (93.65%)
    Lasers: 112500 m³ / 240250 m³ (46.82%)

    Range: 0.1 ls, @10 m/s² => 0.2 m
    Radius: 150 m / 150.2 m
    Projectiles: 22500 m² / 22560.04 m² (99.73%)
    Lasers: 112500 m³ / 9024.016 m³ (1246.67%)

    Second Case: A “fast” hard scifi ship (40 m/s² acceleration capable)

    If the ship doesn’t have artificial gravity or some kind of inertial dampening, then the crew and all lose objects had better be strapped down into g seats that help keep them awake and uninjured. Fighter Jets take upwards of 9 g of acceleration, but only briefly. But we’ll allow for some kind of future tech that uses materials in the g cushions and/or chemicals like “the juice” from the expanse to allow prolonged high g acceleration. Still this would be “combat” maneuvering and not the ship’s typical maneuvers unless it has artificial gravity and/or inertial dampers.

    –Small Ship (Missile, Drone, Fighter)
    Range: 1 ls, @40 m/s² => 80 m
    Radius: 5 m / 85 m
    Projectiles: 25 m² / 7225 m² (0.34%)
    Lasers: 125 m³ / 1156000 m³ (0.01%)

    Range: 0.5 ls, @40 m/s² => 20 m
    Radius: 5 m / 25 m
    Projectiles: 25 m² / 625 m² (4%)
    Lasers: 125 m³ / 25000 m³ (0.5%)

    Range: 0.1 ls, @40 m/s² => 0.8 m
    Radius: 5 m / 5.8 m
    Projectiles: 25 m² / 33.64 m² (74.31%)
    Lasers: 125 m³ / 53.824 m³ (232.23%)

    –Medium Ship (Millennium Falcon)
    Range: 1 ls, @40 m/s² => 80 m
    Radius: 15 m / 95 m
    Projectiles: 225 m² / 9025 m² (2.49%)
    Lasers: 1125 m³ / 1444000 m³ (0.07%)

    Range: 0.5 ls, @40 m/s² => 20 m
    Radius: 15 m / 35 m
    Projectiles: 225 m² / 1225 m² (18.36%)
    Lasers: 1125 m³ / 49000 m³ (2.29%)

    Range: 0.1 ls, @40 m/s² => 0.8 m
    Radius: 15 m / 15.8 m
    Projectiles: 225 m² / 249.64 m² (90.12%)
    Lasers: 1125 m³ / 399.424 m³ (281.65%)

    –Large Ship (Aircraft Carrier)
    Range: 1 ls, @40 m/s² => 80 m
    Radius: 150 m / 230 m
    Projectiles: 22500 m² / 52900 m² (42.53%)
    Lasers: 112500 m³ / 8464000 m³ (1.32%)

    Range: 0.5 ls, @40 m/s² => 20 m
    Radius: 150 m / 170 m
    Projectiles: 22500 m² / 28900 m² (77.85%)
    Lasers: 112500 m³ / 1156000 m³ (9.73%)

    Range: 0.1 ls, @40 m/s² => 0.8 m
    Radius: 150 m / 150.8 m
    Projectiles: 22500 m² / 22740.64 m² (98.94%)
    Lasers: 112500 m³ / 36385.024 m³ (309.19%)

    Third Case: An “Extremely fast” science fantasy ship (100 m/s² acceleration capable)

    If the ship doesn’t have artificial gravity or some kind of inertial dampening, then the human crew is unconscious then dead within a very short amount of time. Extreme g compensation and/or only short maneuvers may be survivable, but it’ll be terrible on anyone in the craft. Automated or robotic (or High G adapted aliens) may be able to fly a ship like this though. This could be a good acceleration profile for a “missile” or drone though.

    –Small Ship (Missile, Drone, Fighter)
    Range: 1 ls, @100 m/s² => 200 m
    Radius: 5 m / 205 m
    Projectiles: 25 m² / 42025 m² (0.05%)
    Lasers: 125 m³ / 16810000 m³ (0%)

    Range: 0.5 ls, @100 m/s² => 50 m
    Radius: 5 m / 55 m
    Projectiles: 25 m² / 3025 m² (0.82%)
    Lasers: 125 m³ / 302500 m³ (0.04%)

    Range: 0.1 ls, @100 m/s² => 2 m
    Radius: 5 m / 7 m
    Projectiles: 25 m² / 49 m² (51.02%)
    Lasers: 125 m³ / 196 m³ (63.77%)

    –Medium Ship (Millennium Falcon)
    Range: 1 ls, @100 m/s² => 200 m
    Radius: 15 m / 215 m
    Projectiles: 225 m² / 46225 m² (0.48%)
    Lasers: 1125 m³ / 18490000 m³ (0%)

    Range: 0.5 ls, @100 m/s² => 50 m
    Radius: 15 m / 65 m
    Projectiles: 225 m² / 4225 m² (5.32%)
    Lasers: 1125 m³ / 422500 m³ (0.26%)

    Range: 0.1 ls, @100 m/s² => 2 m
    Radius: 15 m / 17 m
    Projectiles: 225 m² / 289 m² (77.85%)
    Lasers: 1125 m³ / 1156 m³ (97.31%)

    –Large Ship (Aircraft Carrier)
    Range: 1 ls, @100 m/s² => 200 m
    Radius: 150 m / 350 m
    Projectiles: 22500 m² / 122500 m² (18.36%)
    Lasers: 112500 m³ / 49000000 m³ (0.22%)

    Range: 0.5 ls, @100 m/s² => 50 m
    Radius: 150 m / 200 m
    Projectiles: 22500 m² / 40000 m² (56.25%)
    Lasers: 112500 m³ / 4000000 m³ (2.81%)

    Range: 0.1 ls, @100 m/s² => 2 m
    Radius: 150 m / 152 m
    Projectiles: 22500 m² / 23104 m² (97.38%)
    Lasers: 112500 m³ / 92416 m³ (121.73%)

    (Link to spreadsheet used to generate this data: https://docs.google.com/spreadsheets/d/1vkuZRIaXr5upcPRPZDSIcV3qWnO0M1dQY1apLH2Uihk/edit?usp=sharing )

    In my opinion, there are 4 ranges for a space based fight between maneuverable ships, as follows:

    1) Extreme Range (>1 light seconds distance): Use guided projectiles only (ie, missiles, fighter drones, etc.).
    2) Medium Range (about 0.5-1.0 light seconds out): Near Light speed projectiles (rail guns, gauss weapons, etc)
    3) Close Range (anything < 0.5 light seconds): Lasers
    4) "Melee" range (<0.1 light seconds): Artillery / Massive Slower than Light projectiles / Bombs / Mines

    • Master Zed says:

      The actual range at which you can engage depends mostly on the size of the ship, but these figures should give you a pretty good idea as to why lasers are effectively useless at long ranges in space. The additional burden of having to aim the focal length means that lasers have alot more ways to miss at long ranges.

      Star Wars style “laser bolts” or plasma beams or other “encapsulated” lasers which don’t actually have a focal point can be treated like rail guns, the term laser here I use to refer to actual beam lasers that have a focal point do to the lensing nature of their firing apparatus..

      The >100% at .1 ls for lasers in the above data comes from my gross estimation process, but I left it to give you an idea of how much difference distance can make to lasers.

      So, why lasers as close range weapons, why not just keep using projectiles?
      While that’s certainly one possible approach; lasers do not use up ammo, are MUCH more precise in their targeting at close in ranges, and generally have easier to redirect firing ports. (ie, you can turn a laser lens VERY quickly to track close in fast moving targets – that’s much harder to do with a rail gun barrel.)
      This makes lasers the ideal missile and drone defense – since projectiles will have a hard time tracking the incoming vehicle, but a small array of lasers could literally trap the missile in a web of death beams, then dial in that web until the missile is just plain to big for the web and lasers start chopping it up….

      A similar tactic can be used to make lasers “accurate” at a distance, but again, you’re now talking about an extremely high powered laser set to continuously fire for tens of seconds at a time, and it’s very likely the target craft will simply deploy chaff/diffusion clouds and slip out behind the cloud forcing you to reset the web and try again. Remember, to the target this beam is 0 seconds away and they can easily compensate for its moments – whereas the attacker cannot easily adjust to the target’s movements.

    • Master Zed says:

      Why guided projectiles at >1 light second?

      Simply put, they adjust course as they get closer to their targets and the sensor data becomes increasingly real-time. Basically it’s “I launch in your general direction” and then the guided vehicle makes minor course corrections as it approaches its target and the “potential location bubble” collapses down to be almost the same size as the “actual position” bubble.

      • tctaylor says:

        Master Zed, I think every conversation I’ve had or read about far future space combat converges on the same conclusions (as I think you’re doing here):
        – Different weapon technologies are optimal for different range zones, and lasers are terrible long-range weapons (except against a predictable target such as a ground installation, in which case they can be very useful).
        – Without cheating by adding in inertial dampeners or some such, drones and missiles are the most effective weapons, and the best way to win is not to have the biggest battleship, but field the most drones.

        At the start of the Human Legion books, which this recoil post was introducing, the conventional strategy for winning a space battle is to turn up with manufactory/carriers that build/carry vast quantities of drones and deploy more than the enemy. There are escort ships and ground attack craft, but if you want to capture a planet, you win orbital superiority with drone fleets and then threaten to throw rocks down the gravity well unless the planet surrenders.

        I like all your reasoning except I question the idea of focused lasers. I’ve seen complicated proposals for lensing in point defense, and I’ve written in my next novel about a laser defense grid with a preset focal length designed to disable boarding craft. But if I was firing a laser at another ship, then rather than lensing, I would use a collimated beam (parallel light beams, though not perfectly parallel because they’re also waves and so will diffract). At distances of a light second (300,000 km) the loss of power from beam spread will add significantly to the problems of locking on to a target point because you have correspondingly less time to punch through the armor. In that series I put 1 ls as extreme range, but effective range doesn’t start until 0.1 light seconds. Mind you, I’m writing in a series at the moment where obedience to physics is much looser, and that presents its own challenges and opportunities. It’s a lot of fun moving up and down the sci fi hardness scale 🙂

  4. Master Zed says:

    To my knowledge, all lasers are collimated beams (https://en.wikipedia.org/wiki/Collimated_beam), it’s part of what makes it a laser (otherwise you’re talking about a “flashlight”).

    Also, to my knowledge, all lasers have a focal length (it’s a fact of physics – the uncertainty principle means you can never have a perfectly aligned laser, the reality of the mass of your lasing medium, imperfections in the escape aperture, etc. means you cant really come even close to that theoretical limit). From above link: ” A perfectly collimated light beam, with no divergence, would not disperse with distance. Such a beam cannot be created, due to diffraction”. You can use a “flat” lens to ignore the focal point, but what you’re really doing is setting the focal point to 0 (the laser will start diffusing at the source, which is the worst case scenario on space scales, so all efficient space based lasers would be lensed in my opinion – basically if you’re gonna make an unlensed laser for use past 0.1l ls, take the energy you’re putting into making that laser, and fire a projectile instead.) The “non-lensed” laser is basically why at 0.1 ls all my lasers exceed 100% hit rates, my assumed “5m effective window” is further than the craft can travel unobserved within the time frames produced at that range. This is also why I left the >100% numbers in the data, the laser is effectively operating at that kind of relative power level as ships at that range are subjected to much more focused lasers no matter where they are within that beam’s focal length, so the laser exceeds a 100% “average” hit rate on account of the exponentially greater effectiveness in that now less than 5m window. But that window indicates the “effective” window, so this extra power is likely being lost to beam penetration anyways…)

    So I don’t think you can “high tech” away the focal length problem without crossing into science fantasy (ie star wars laser “bolts” and the like). Higher laser power and high tech engineering with better manufacturing tolerances can increase the effective length further from that focal point (you can be off from the optimal point by more, so my 5m “target window” above may become 10m, or 20m – but that is still just a linear increase in those percentages and still only approaches the ballistics numbers – so at best, it operates exactly like a projectile – but is using exponentially more and more power to approach that “ideal”, see below).

    Beam spread is an exponential drop-off because the crossectional energy in the beam is basically constant at any given point along the beam (because the emitter creating the laser is operating at a constant power level), so as beam width increases, that energy is spread out with the formula of the area of a circle (πr²). Which means a simple doubling of the radius (or diameter) equates to 1/4 as much “pressure” / power to do damage to the target (it’s an inverse square law – so like a magnet, get them just a little ways away and the force becomes extremely weak and rapidly approaches effectively 0). Mind you, this is still MASSIVELY preferable to the cubic drop off of an unfocused radiation weapon (like a nuclear explosion), but while lasers are exceedingly coherent, when talking about ranges like a light second, this rapidly decreases their effectiveness. To give you an idea of why this is not so good a way to try to build a combat laser, if we use my 5m focal point as our starting point, then making that a 10m effective focal length means needing 4 times the power in the laser, and you’ve only doubled your chances of “hitting”. To make your laser “as effective” as a projectile at 1 ls against a 1G ship requires 64 times the power (if you look a the 1 ls / 1 g ship data, you’ll see projectiles are about 8 times as effective, so 8^2 = 64 times as much power needed, and against higher G targets its exponentially worse needing around 7000 times the power to get the same effectiveness as a projectile.) In truth, my 5m window was a pretty generously powerful laser to start with, since I wanted to give the laser the benefit of the doubt/present a “best case” scenario to make the point harder to dispute, ie, the more “accurate” you make the model, the worse it gets for the laser.

    A truly overwhelmingly powerful laser could potentially have enough energy to destroy everything in its path on a planetary scale (but it’s always a matter of scale). However, besides probably being a horribly inefficient way to deliver that energy to your target, you’d probably end up needing Einstein’s equations to describe the beam behavior, and might be talking about a plasma stream more than a laser at that point as the energy densities begin warping spacetime and effectively gain gravity which pulls matter into the beam and begins fusing it? (I’m not a laser expert, but I am pretty confident that at certain energy densities you basically start building a sun spawner/black hole emitter rather than a laser – but again, that mini sun or black hole forms at the focal point, sooo…)

    Basically, lasers are a grossly inefficient method of delivering energy at > 0.5 ls ranges based on my research (again, not a laser expert mind you) except against completely predictable targets where the computer can accurately focus the beam. What lasers are good for though is point defense, since at close range you can effectively instantly create a “laser wall” for relatively low power and with much greater response time/accuracy. Grossly high powered lasers are really only good for hitting relatively predictable targets – like a ship that focuses solar radiation from a sun to lase a planet or space station. As a point defense they’re unnecessarily powerful (once your target is vaporized all the rest of that energy is wasted), and at long range they require exponentially more power than launching a reasonably accurate projectile or missile and again become ineffecient.

    Another thing to consider when considering a “fixed focal length” laser is that adjusting the focal point of a laser is insanely simple. VERY simple optical techniques can move the focal point of a space based laser quite far VERY quickly. This is why lasers work so well as you get closer – as the time delay in information feedback drops, the laser’s aiming program can very accurately aim the focal length and exponentially increase the beam’s effectiveness.

    All of this is why the “aiming” part dominates at space based ranges. The light speed limit means that information correlates to reality less and less, and the 3 dimensional nature of the laser’s focal length means the less correlated the data, the less effective the laser in an exponential manner. These are simply byproducts of the light speed limit and the physics of lasers.

    Some comments regarding the “drone swarm” tactic :). While it is an entirely a viable “firm” scifi strategy, let me play besieged planet for a bit to give you some ideas of how I might counter it if it’s the only strategy (or even predominant strategy) being used.
    1) Assuming these drone factories use local materials to basically manufacture drones, then I win because planet mass > asteroid belt mass and planetary (or near orbital) factories are gonna be WAY better established than a mobile ship/station. (At least until you talk about flying in a fleet of these things and spreading them throughout the system – at which point, the attacker should switch to planet killer lasers for the amount of overwhelming force we’re talking about here.)
    2) Assuming these factories are fairly stationary (ie, move through the asteroid field in a roughly predictable manner), you bet I’m including solar lensing satellites scattered around any system I’m interested in defending, which means the amount of time your factories have to produce drones is proportional to the distance they start from the planet they’re trying to overwhelm (In our solar system the asteroid belt is on the order of 10-20 light minutes from Earth for example, meaning once an attack has been detected, you have about 20-40 minutes before those factories are located and my solar satellites begin focusing terminal beam energy on them – like ants under a magnifying glass. Again, this is where that focal point math starts working in the defender’s favor since the targets are slow moving/predictable – they’ll have large focusing lenses already in place, they will have detailed information on planetary motion, will be monitoring likely factory incursion points continuously, etc. etc.
    3) I’m placing mines or defense installations at all the “best spots” in the system – I don’t care if they’re half baked junk drone producers, I’ll do it just to deny the attacker resources. And yes, they will self destruct and vaporize the asteroids in their vicinity / moon they’re on before they allow themselves to be overrun. It’d basically be like trying to fight a land war in Russia during the winter – the defense line just keeps falling back leaving nothing for the attacker to build drones from and eventually wins the war of attrition. This MAY result in an unlivable system decades or centuries down the line, but you might be able to deal with that given the timescale, and it’s probably better than the alternative.
    4) I’m going to have a FLEET of drones already produced and stationed throughout the system to make sure I have the upper hand against anything other than spectacularly overwhelming attack force. (The kind where fighting doesn’t even happen, because the fight is so obviously one sided, even unconditional surrender is preferable to the losses from the fight – assuming a reasonable enemy.)
    5) I’m going to have powerful planet side lasers, railguns and missiles that can intercept and break apart any large slow ships or non-maneuvering kinetic kill weapons in/approaching orbit. Unless your kinetic kill asteroids are is going something like .99C, my ground based super computers will locate, extrapolate and focus those lasers and railguns on the incoming projectile before it can hit the surface. Remember how I said the moon is 1ls away from Earth and how lasers make GREAT point defense weapons out to about 0.1-0.5ls? Yeah, you’re gonna have a tough time getting drones or kinetic kill weapons to the surface of a combat ready planet or even INTO any kind of orbit. I can see drone based space superiority allowing you to remove the satellite point defenses (that likely have 10g-esk maneuvering capabilities that make them essentially immune to long range projectile or laser attacks.) But you’re going to have to deal with my planet side lasers, missiles, and railguns are gonna make pretty quick work of your drones unless you take them out first. And forget using drones, missiles, or projectiles to attack those installations – they’ll be deep underground with only firing ports visible on the surface. Firing ports which can be rebuilt on the timescales of a planetary siege btw, ESPECIALLY if we’ve got the kind of drone production technologies you’re talking about.

    So really a planetary invasion comes down to a layered siege strategy. (Assuming hard to firm scifi where things like planetary shield generators and death stars aren’t a thing)
    Step 1) Recon. If you go in blind, you’re probably gonna get blasted out of existence by some hidden instillation.
    Step 2) Remove outlying defense installations with fast moving attack craft. These craft can more easily match and fight with highly mobile satellite/small station defenses scattered throughout the system. This wave will not be up to taking out planetary or space station type defenses though – the whole point of the fast attack craft is that they’re using hit and run type tactics to avoid such confrontations. Depending on the nature of FTL in your setting, this would either be via pre-planned near light velocity “fly-bys” or FTL jumps to and away from the targets. Basically the idea is to get in, do as much damage as you can, then get out before the defenders can organize an effective counter attack.
    The reason you can’t bring larger ships into the conflict yet is that they are relatively slow (and therefore extremely vulnerable to the kinds of platforms you’re now taking out). Those drone factories are sitting ducks against massive solar focusing lenses.
    Step 3) Deal with stations and small moon/planetoid based defenses. You’re still on the clock here and have to do hit and run type attacks to prevent resources elsewhere in the system from annihilating your attack force – but you have 10s of minutes to fight in and need to overwhelm massive station defenses. You’re not gonna be manufacturing drones so much as showing up with a large overwhelming force and trying to down one target at a time – basically this is divide and conquer.
    The reason you’re not approaching the planet yet is that the planet has a predictable orbit, which means that if you move your fleet into orbit – it too now has a predictable orbit and becomes extremely vulnerable to large scale weapons in other orbits (nuclear missiles, attack drones, high powered lasers, etc).
    Step 4) Having now dealt with all non-planet based system defenses you can start dealing with the planet based ones. First thing you’re going to need to do is likely some more recon to ascertain planetary point defense installations. Then start picking them off with powerful lasers from very far away. (The planetary orbit is predictable, and so too are the motions of the installations on the planet, meaning lasers – or rather huge solar lensing ships – are a viable attack method.) As a side benefit, you’ll be “casting shadows” on the planet and likely denying it (and its satellites) solar power generation. Assuming you’re using only solar lensing ships, this phase will take roughly 1/2 of the planet’s day, since only half of the installations will be visible at any given time. And since you’ll likely be attacking from light minutes away, this too will involve strike and move type tactics. Which means in practice what you’re actually doing is probably taking a few planetary days to significantly reduce planetary defense to a point you can accept the attrition rate rather than completely eliminating them. The reason you can’t send in the drones at this point to take out orbital defenses is because they’ll be absolutely shredded by planetary installations – the surface has to have have so much capacity to protect its near orbit or the planet could simply be taken out by a single well aimed asteroid – so we’re not talking about planetary sieges at all in that case. If the system has multiple hostile planets, this process would have to occur at all of them you you’re unlikely to be able to maintain the advantage in the next step.
    Step 5) Having weakened the surface based defenses (and maybe getting a lucky hit on a few satellites as well) you can now progress to establishing orbital superiority. (Drones would work very well for this, especially since you’ll likely be hunting down very maneuverable defense satellites.)
    Step 6) Move in the big guns. Your large slow ships are now free of worry from orbital based lasers/rail guns/missiles and can now move in and either threaten further bombardment or start deploying troops, or just deploy a truly massive focusing lense and threaten to boil off the planet’s seas… The reason you couldn’t do these things in in step 4 is that the orbital satellites would’ve been able to pick of such large ships and/or their projectiles while they were trying to deliver attacks.

    anyways, there’s my buck and some change on these issue. 😉

  5. Master Zed says:

    Oh – just had a thought. If you’re talking about deploying these drone factories outside the system – like in the Oort cloud – then waging a months long siege of a system, then yes – the large immobile factories are protected by their distance and the sheer volume of space that’d have to be searched to find them. They’d have enough material (over the course of months anyways) to effectively build drones forever. Meaning drone production RATE and relative drone quality become the dominating factors – as you have more material out in that massive cloud than the system does. The system would be trying to defend itself by getting enough drones out into the Oort cloud to locate these factories, and the factories would be trying to deploy enough drones to prevent this. Whichever side got dominance first would basically go through the steps I listed above with impunity, making the battle actually about establishing drone superiority.

    The system is still going to have superiority against an equivalent force due to the extra energy available (they’ve literally got a sun on their side). But the attacker might have multiple systems worth of attack resources – so long drawn out war of attrition.

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