A submarine that hurtles through the depths like a jet through the air? The Chinese say they invented it: the secret to its incredible speed would be new, incredible laser thrusters. But wait a moment before picking up your jaw that fell to the ground: there is also the other side of the coin.
The promise of an undersea revolution
I submarines have always been a bit like ocean turtles: more or less slow, and clearly inexorable. Now, however, Chinese researchers at Harbin University claim to have found a way to transform them into real underwater cheetahs. How? With laser thrusters, a technology that promises to make these steel beasts travel at speeds never seen before.
How do they work? Let me put it in simple terms. Imagine covering the hull of a submarine with a network of optical fibers thinner than a human hair. These fibers shoot powerful lasers into the surrounding water, creating “mini explosions” that propel the submarine forward. It’s as if the submarine were swimming in a bubble of vapor that reduces friction with the water. By how much? By a lot.
The use of lasers as a form of propulsion dates back to 1972, when it was originally proposed as a method of powering spacecraft. In atmospheric travel, the technology is
simple enough and understandably so: the underside of a plane is hit by a laser that superheats the air underneath, creating a plasma that explodes the air and pushes the aircraft upward. Atmospheric laser propulsion has only been tested with scale models under controlled conditions and has not yet produced a fully-fledged manned aircraft. “Underwater” use would be a first.
Mind-boggling (and seasick) numbers
According to Chinese researchers, these laser thrusters could generate a thrust of 70.000 newtons. For those who don't know physics, that's a force comparable to that of a supersonic jet. Translated into practical terms? We're talking about submarines that could travel faster than the speed of sound underwater.
Imagine submarines that can evade any torpedo, reach any target in the blink of an eye, and practically disappear into thin air. It would be every admiral's dream and every enemy fleet's nightmare. Such a weapon would completely change the rules of the naval game.
But there's a but (and what a but)
As I mentioned at the beginning of this article, there is a small detail to consider. And when I say small, I mean huge. All this power comes at a price, and that price is paid in decibels.
You see, submarines are a bit like ninjas of the ocean. Their strength is in going unnoticed. And all those mini explosions created by lasers make a hell of a racket.
The phenomenon is well known, it is called cavitation. Basically, the bubbles created by the lasers, when they pop, make a noise similar to “rocks in a tube.” And underwater, that noise travels for miles and miles. It’s like turning on a lighthouse in a dark room: yes, you can move faster, but everyone knows exactly where you are. And that’s the crux of the matter.
The sad reality: speed or stealth, you can't have both
In the submarine world, silence is life. A noisy submarine is a dead submarine. So, as cool as the idea of a supersonic submarine might sound, in reality it would be practically useless. It would be like a ninja wearing bells: fast, yes, but not very stealthy.
And this could also answer a “conspiracy” question: why did China make this research public with an obvious military objective? Maybe, and I say maybe, they don’t believe it too much either.
The Future of Submarines: A Loud (or Silent as Always) Mystery
We probably won’t see submarines equipped with laser thrusters, at least not in this form. The real challenge remains finding a way to increase speed without compromising stealth. And until that dilemma is solved, submarines will continue to move as they always have: slowly, silently, and lethally.
Maybe while you are reading this article, in some secret laboratory, someone is already working on a solution. After all, history teaches us that today's impossible could be tomorrow's normality. But for now, if you hear a strange noise while you are (lucky you) taking your last dives in the very open sea, don't worry: it's probably just a fishing boat.
