All you never needed to know about lasers.

<< Mil-itary precision

Science fiction weapons: Lasers (Part 2) >>

Happy Thursday everyone. This week, by popular request, I’m going to start looking at weapons in science fiction. Even though science fiction is a diverse field, with many different types of story, there are some common tropes when it comes to weaponry, and these are what I’ll focus on. We will bring in the heavy hitters—the Star Wars-es etc.—but I’ll try to cast the net as wide as I can. Please dive into the comments, though, and bring up any favourite films or shows of yours which I miss.

I’m breaking this rant “research” into a few different parts. This week (and hopefully next week) I’ll be looking at “lasers” in the broadest sense of understanding, basically anything that goes “pew” and/or fires a beam of light at a target. As we’ll see, some of these weapons aren’t actual lasers, at least in fan canon, but I’m going to group them all in as “laser-adjacent” weapons, under the justification that, if they aren’t lasers, then they probably should be, or at least most of their properties should be similar to those of lasers.

In future posts we’ll look at melee weapons such as lightsabers and we might also cover other classes of SF weapon. As always, I’m open to your suggestions in the comments or by email. In each post, I’m going to look at the technical realism of the weapons shown on screen (this week), but I’ll also look at the realism of how they’re used by the fictional futuristic military forces, at the tactical, the operational, and the strategic level (next week).

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Technical critiques

Before we dive in, let’s settle on some definitions. What do I mean by “science fiction”?

This is perhaps a bit arbitrary, since many science fiction tropes (I’m looking at you, Star Wars‘s Jedi and The Force) can be just like magic. It’s not a clear dividing line, but the difference for me is the focus on technology as a way of driving the plot rather than as a prop. Yes, it’s subtle, but I get to make the rules. If people are interested, we could do a whole deep-dive into the MCU some day. Let me know!

What’s wrong with bullets?

Pre-World War 2 weapons technology is more effective than most science fiction weapons. Don’t believe me? This is the M2 Browning .50 cal / 12.7 mm heavy machine gun:

It fires 40 grams / one and a bit ounces of copper-coated lead out the business end at a speed of nearly a kilometre per second, engaging targets nearly two kilometres away. And it does this eight times per second. It dates from the early 1930s and is still in use worldwide. If you are lucky enough to live in the good ol’ US of A, you can probably fire one of these at your local range¹:

Update: Video above seems to be age-restricted so the embed doesn’t work, it’s two guys firing an M2 (the weapon in the pic above) on full auto on what looks like a home firing range. Awesome.

This is the E-web heavy repeating blaster from Star Wars:

It can fire a bolt of energy at a target up to 750 m away, and do a fair bit of harm, I guess (Star Wars fandom weapons specifications are detailed, but not that detailed). It fires at about the same rate as the M2 Browning, but the blaster bolts travel about thirty times slower².

In other words, the futuristic³ science fiction weapon is only a fraction as effective as the 1930s weapon which is still in use today. Never mind Jedi powers and lightsabers: the Rebel alliance could have had far more success breaking into a museum and looting some firearms. How can the fearsome fighting forces of the future come to rely on such ineffective weapons? Maybe gunpowder was never discovered in the Star Wars galaxy (after all, it is far, far away). But this seems like a stretch given their other technological achievements (like faster-than-light travel). The target effect of a .50 cal bullet is pretty impressive too, making mincemeat of up to three plates of body armour. Stormtroopers wouldn’t stand a chance.

Firearms will work in space, too, and on any planet or moon that our heroes find themselves on. What’s so great about firearms? Well, unlike laser or plasma/blaster weapons, which need to carry around big hulking power packs, firearms carry all of their incredible potential energy wrapped up in a little chemical package inside the cartridge. It’s the same reason why electric cars, for all their recent advances, are still nowhere near internal combustion engines when it comes to energy stored.

The only downside of projectile firearms is their speed, which will quickly be a limitation as distances between ships become significant, as they very much will in space. Despite this, filmmakers favour the laser, the phaser, and the particle beam.

Stop getting lasers wrong!

By definition, lasers travel at the speed of light, aka the cosmic speed limit. Therefore they will  get you around the problem of distance.  Some films and games get this aspect of laser weapons right:

Many others don’t:

We could include the aforementioned Star Wars blasters in the above category of offenders, but some clever retconning by the Star Wars fandom⁴ has confirmed that these fire plasma bolts powered by compressed Tibanna gas, a substance that is found and mined on the planet Bespin—of Cloud City fame, and the place where Darth Vader didn’t say “Luke, I am your father” and inspired some sick medieval art:

So the extensive Star Wars and Star Trek fandom can successfully explain why blasters don’t act like lasers, but can’t explain why both sides would choose to use such terrible weapons. Star Wars aside, though, it’s clear that weapons designers of the future have managed to do the improbable (and the inadvisable): slowing down lasers and particle beams to a fraction of their normal speed. This, of course, is in no way sensible. Remember, you’re trying to hit a target. Light speed is good for that.

The other big problem here is that we can see the laser beams, but these should only be visible if they’re interacting with something. Remember in Metal Gear Solid when you had to smoke the otherwise pointless pack of cigarettes to show up the alarm lasers? It’s the same principle here. Those laser beams in Moonraker shouldn’t be visible, because there’s nothing in space for the beam of light to interact with. Moreover, by interacting with smoke or sand or dust, the laser is giving up some of its power en-route to the target.

Finally, I’ve never seen anyone on screen shoot a laser straight through a window, but this of course should be possible, unless the window is made from a special glass that blocks certain wavelengths of light (which would also mean, of course, that normal light of that colour wouldn’t get through):

Big lasers can make big problems

Superweapons play an important part in lots of science fiction stories, because they usually play out on the grand scale of star systems and galaxies. Probably the most iconic example is the Death Star’s superlaser⁵ from Star Wars⁶, seen here obliterating the planet Alderaan:

The Star Wars fandom makes a valiant attempt to rationalise this destructive capability, and has even calculated the power output of this laser to be 240 million million million million million⁷ Watts. Since it’s just a beam of light, it presumably destroys its target by instantly heating it and vaporising it⁸. This superweapon is actually one of the more realistic applications of lasers in science fiction. Assuming you can get a laser that powerful (which is, of course, a massive “if”: the number described above is a million times more than our own sun’s power output, but this is a story where we believe in hyperspace travel and Jedi masters, after all), then the Death Star and its superlaser are realistic. Even the time lag you see between the laser leaving the Death Star and hitting Alderaan can be explained by the massive distances involved. I’ll even excuse the green shimmer of visible laser light, since it’s travelling such huge distances and outputting so much power that the very very few particles in the way between the Death Star and Alderaan get vaporised in a spectacular burst of green light, which is what we see.

Far less forgivable and understandable is the execrable “Starkiller Base” from the Star Wars sequel trilogy:

This seems to be a laser/pillar of fire that can travel instantly across the galaxy (lightspeed be damned!) and obliterate several planets at once:

I’ve written about this before, so I won’t labour the point here, but it breaks all bounds of credibility and pushes this film (as with the whole sequel trilogy, unfortunately) away from science fiction and more towards the realm of magic and fantasy (see my taxonomy at the top of this article).

Military lasers in reality

Lasers are, of course, a real thing, with real scientific, industrial, and even military uses. Armies, navies, and air forces use lasers to:

• Find the range to a target, by shining an invisible laser beam at it and measuring the time it takes to reflect back to the source
• Designate targets for smart bombs and missiles, by shining an invisible laser beam at the target, which pulses with a certain code. The munition then looks for that tell-tale pattern of light and homes in on it
• Help aim weapons in close-quarters⁹ fighting by shining a visible light which reflects off the target and is seen by the firer (and everybody else). This can also be done with an invisible laser (see below) and used in conjunction with night-vision goggles which can pick up on the infrared light).

Normally such lasers are invisible. Not only can you not see the beam (as explained above, any laser beam is invisible apart from the effect it has on particles it interacts with along the way), but the light itself is in the infrared spectrum, i.e. at a lower frequency and longer wavelength than our eyes are capable of seeing. This makes sense, when you think about the uses: you don’t want the enemy noticing beams of laser light bouncing back off their tanks or bridges which you’re planning to blow up¹⁰.

Ah yes, you say, but that doesn’t really count, does it? What about real lasers, like we see in the films? Lasers which can kill people? Well, there’s certainly plenty of money being thrown at research in this area. So-called “directed energy weapons” are not just on the drawing board, but are operational and being used today. Here’s just one example, the US Navy’s LaWS, which was deployed ten years ago and has already been replaced by a more powerful laser:

Many of these prototype laser weapons platforms are deployed on ships, and a big reason for that is their size and power requirements. Nothing short of a nuclear reactor is going to give the oomph that these weapons need. Their primary purported uses are for targeting small, fast targets, such as small boats, aircraft, and inbound hypersonic missiles. The LaWS laser has a maximum power output of 30 kilowatts, so it’s still about a million million million million million times weaker than the Death Star, which is probably a good thing.

As for particle beams, the other type of directed energy weapon seen in science fiction, these also exist in real life, and have even (unwittingly) caused injuries, but tend to be a bit unwieldy. For example, the Large Hadron Collider at CERN weighs 14,000 tonnes, draws 200 megawatts¹¹ of power, and takes up about 20 km of subterranean real estate, so there’s still some way to go in terms of miniaturisation:

Conclusion: You deserve better lasers

As seen from the examples above, lasers (or laser-adjacent weapons, such as particle beams or plasma weapons) are to go-to weapon for futuristic, space-faring heroes and villains in science fiction. It’s easy to understand why this is the case: just when science fiction was exploding as a popular genre, lasers were the cutting edge¹² of scientific progress, along with atomic weapons. The latter are less popular (but not entirely absent from science fiction: I might cover them in a later post), probably due to Cold War and modern sensibilities putting nuclear weapons into a different, more taboo category of weapon, as well as their lack of utility in on-screen, small-scale battles. Lasers have remained popular, however, even as the trope has branched out into particle weapons, plasma weapons, and other “adjacent” types of gun.

But why do directors and screenwriters get them so wrong? I think there are three big reasons, all of which are understandable and forgivable, as these things usually are:

1. Familiarity. Science fiction wants to explore the speculative, but it doesn’t want to go too far, especially in TV and films. Big set-piece battles are a popular feature of science fiction and space opera, but also of war movies. Tank battles, aerial dogfights, and ground assaults have their own familiar tropes on screen, and the audience probably doesn’t want something too unfamiliar, even when you swap the plains of Kursk for space or the beaches of Normandy for the ice-fields of Hoth. For this reason, screenwriters and directors keep a comfortable level of similarity between real and speculative weapons. Often, they just put some papier-mâché cladding onto real replica guns to give the right level of science fictionality. All of this means that the weapons can’t be too powerful and have to act a little bit like real-life weapons.
2. Visual understanding. Directors want the audience to “get” what’s going on. If you read the science fiction of Iain M. Banks or Alistair Reynolds, to pick just two examples, you get excellent descriptions of what weapons and warfare of the future might look like. As books, these work very well, but I doubt they would transfer onto the screen, at least not easily. Making lasers and phasers and blasters travel slowly and with bright colours really helps the audience see what’s going on. It’s like how rifle barrels flash brightly and bullets spark off the ground in movies: it’s just a visual aid, it’s not very realistic. You can also colour the fire differently to denote who is shooting. To come back to Star Wars, although both sides predominantly used red blaster bolts, George Lucas supposedly used a convention in the original films where the rebels fired from left to right on the screen and the Empire from right to left. I’ve watched a few clips to try to disprove this but it seems to hold up for the most part.
3. Sanitisation. Science fiction often (though by no means always) targets younger viewers. As a result, there’s less tolerance for blood and guts and gore. Lasers and laser-adjacent weapons give filmmakers an easy way to dispose of baddies on screen without an excess of visible injury. Phasers in Star Trek often make the target just disappear: no gore at all! In reality, such weapons would be far more powerful and far more bloody (which I’ll cover next week).

The second and third reasons above also explain why characters in science fiction don’t use modern-day gunpowder technology. It would be harder to visually mark what’s going on and would make for much bloodier outcomes¹³, which would result in tighter film ratings.

While I obviously understand the reasons behind how we got to where we are with lasers, I still think that filmmakers have been missing opportunities to really explore the realm of what’s possible with this type of weapon. Dune is a recent example which shows how silent, swift, and deadly lasers can be as a weapon of war:

That’s all we (or at least I) have time for! Next week we’re going to look at how these weapons are actually used in battle and in grand strategic campaigns, and subsequently we will look at other types of futuristic weapons, like lightsabers or photon torpedoes. Let me know in the comments below if you think I’ve missed anything to do with lasers: I know the examples here have been Star Wars-heavy. Thanks, as always, for reading, and make sure to share it with like-minded folks and subscribe, if you haven’t already.

Featured Image: Star Wars, Twentieth Century-Fox (1977)

1. Yes, I’m very jealous. ↩︎
2. The source linked above makes for interesting reading (interesting if you’re a pedant like me) with a long discourse on blaster bolt speed and a link to a YouTuber who actually measured the speed of various blaster weapons in Stars Wars: Battlefront video game. ↩︎
3. I know Star Wars is set “a long time ago,” but you get what I mean. ↩︎
4. I should mention that the Star Trek fandom likewise explains that a “phaser” actually fires a beam of “nadion particles”, so it’s also a particle weapon. ↩︎
5. In Star Wars canon, it goes (in increasing order of destructive power): Laser -> Laser cannon -> Turbolaser (which has nothing to to with spinning machinery) -> Superlaser ↩︎
6. The name of the film is Star Wars, and I’m sticking to that. I’m not a purist and don’t have anything in particular against the prequel trilogy (I greatly enjoyed them as a youngster, and they are far better, at least, than the sequel trilogy), but I also don’t like how Lucas changed the name of the film subsequently to Star Wars Episode 4: A New Hope. ↩︎
7. 2.4 x 10³² ↩︎
8. So we can do a bit of a sense check here on the number above. The energy required to heat something up is the mass of the target, multiplied by its heat capacity, multiplied by the required rise in temperature. Let’s assume that Alderaan is the same size as Earth (it’s classed as a “terrestrial” planet), which is 6 x 10²⁴ kg. The heat capacity of rock (Google) is (very roughly speaking) 1000 J/kg.K. And let’s assume that we want to raise the temperature of the planet by about ten thousand degrees. This means that the energy we need is 6 x 10³¹ Joules, which the 2.4 x 10³² Watt laser can output in a quarter of a second. It checks out! ↩︎
9. These laser sights are only effective at close range, and would be unlikely to be used by snipers at long distances, despite what we often see in movies. This is because light travels in a straight line, whereas a bullet, being subject to gravity, travels in a parabolic arc from the barrel to the target. ↩︎
10. Of course, the enemy know this too, and most likely have infra-red detectors on their tanks so that the tank knows when it’s being “lasered”. Some modern types even respond instantly to detecting a laser by loading a round and traversing the main gun to point back in the direction of the laser source, so that all the gunner or commander needs to do is confirm the target and fire to take out the threat. ↩︎
11. Still a million million million million times weaker than the Death Star. ↩︎
12. Sorry ↩︎
13. Although they can be non-gory even with firearms, e.g. by using lots more big and fiery explosions which knock people over, and never actually showing bullets hitting their targets. Or, if you’re Sergio Leone, by shooting guns out of people’s hands. ↩︎