Science Fiction is rife with laser weaponry. The X-Wings in Star Wars feature laser cannons, and the heroes of Battlestar Galactica carry laser pistols. But, how realistic are those?
What is a laser?
Laser is actually an acronym that stands for Light Amplification by Stimulated Emission of Radiation. That doesn’t really tell you a lot, though.
To explain lasers, we first have to look at light. As you may or may not know, light has a specific wave length and a direction. The wave length determines the color. Light is rarely of one wavelength, however. It’s a mix of different wave lengths. Pure white light is actually a mix of wave length spanning the whole human visible spectrum.
Since the sixties, we’ve been able to use technology to create light using a very small spectrum of wave lengths. And that is a laser. A beam of light of a narrow spectrum of frequencies and almost identical waveforms. This is called coherence.
Because light is coherent, it can be focused to a very small spot, and doesn’t diffuse as easily. This means that a beam can travel a long way and stay a thin beam. Light is energy, so coherent light can be used to transfer a lot of energy to a fixed point far away. This is why you might be able to create weapons from it. A gun works in a similar fashion: it charges a bullet with kinetic energy which is then transported to a fixed point a distance away. Human bodies don’t do well with large amounts of kinetic energy applied to places, and they don’t do well with large amounts of light energy (heat) either.
Sounds good!
Sounds very weaponizable, right? The advantage of a laser gun over a kinetic gun is that light can travel far faster than a bullet, and over far larger distances. And a laser gun doesn’t jam. And indeed, attempts have been undertaken to create such weaponry.
Unfortunately, lasers have proven to be less useful in practice. The biggest problem is that high energy lasers suffer from what is called thermal blooming. The air the laser travels through absorbs some of the energy. That results in energy not ending up at the place you’re aiming for. And it gets worse with smoke, and in clouds. This severely limits the effective range of a laser weapon (or requires far more power).
Laser pistols might be viable, but creating a powerful enough beam, along with a power source in a small enough package has proven beyond our abilities. Perhaps advances in science will make it possible, but that still might not make laser weapons viable. There is another problem.
You see, there is also economic viability. Even if we can build a laser pistol, it’s questionable if we can build one that is as cost-effective as a bullet-based one. Lasers will only become viable in actual warfare if they offer either a clear advantage over regular bullet-based weaponry, or if they are cheaper. If you can buy ten kinetic guns for the price of one laser gun, the laser gun would need to be ten times better than the kinetic gun. Of course, ‘better’ can mean many things depending on the situation (range, accuracy, less lethal, more lethal, …), but as you can see, that we can make laser guns, doesn’t automatically mean we will.
Laser guns in scifi
Scifi laser guns have very little to do with current reality. If you look at the size of the lasers on an X-Wing, for example, you’ll notice they are not that big. No powerful laser currently exists of that size, not if you include the power source, anyway. For handguns, the sizing is even more problematic. Especially since you often don’t see any power source ever.
Worse is actually the depiction of how they work. Laser weapon fire is usually shown by bars of light flying across the screen. Ever seen a laser pointer do that? You don’t see the beam, only the point where the beam intersects with a target. Also, it travels with the speed of light, literally, which you can’t see flashing across the screen like a bullet.
Of course, ‘laser’ might be a misnomer. There are alternatives to lasers that can produce the effects described: plasma weapons or other particle weapons for example. And then there’s gauss rifles and railguns. Which is why, if you pay attention, a lot of science fiction stories don’t use the term ‘laser’, but either something else, or they don’t name the underlying technology at all.
Summary
Science fiction stories use the proverbial ‘laser gun’, but they rarely follow the actual science. Television and movies are, as is often the case, the worst offenders.
Does that matter? Not really. The stories are no less fun if the science if wrong, but it does put the burden on the creators to explain the rules of their weapons, because the rules of science clearly don’t apply.
And if you are a writer, please don’t be lazy and stick ‘laser’ on things that are clearly not lasers.
