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Future Weapons

Ray guns! Death rays!

The terms conjure images of the golden era of space adventurers—Buck Rogers, Flash Gordon. But in truth, future weapons have been a crucial aspect of science fiction since H. G. Wells armed his Martian invaders in War of the Worlds with heat rays that ignited everything in their path.

Wells concocted his future weapon by combining the idea of searchlights with infrared technology, but scientists at the time were already working with all sorts of new radiation—X rays and gamma rays. By the 1920s a few of them, notably Nikola Tesla in the U.S. and Harry Grindell Matthews in Britain, made the somewhat dubious claim that, indeed, a death ray could be built. Pulp science-fiction readers may have willingly suspended their disbelief, but top scientists certainly didn’t, and after World War II, a high-level review panel proclaimed death rays to be an impossibility.

And unfortunately, the killjoys were right. Even nuclear radiation doesn’t kill instantly on contact.

Just 15 years later, however, the first laser fired bright pulses of red light, and popular science writers began envisioning applications for “The Incredible Laser”—applications ranging from eye surgery to laser cannons. But real scientists were, once again, more skeptical. So skeptical that laser pioneer and future Nobel laureate Arthur Schawlow posted an “Incredible Laser” article from the Sunday supplement This Week on his laboratory door at Stanford along with the note: “For credible lasers, see inside.” Needless to say, nothing inside was anything like the wildly overenthusiastic—although nominally factual—newspaper piece.

Half a century later, though, the landscape has changed again. We certainly have the laser eye surgery part down and, surprisingly, we’ve even come a bit closer to the cannons as Northrop Grumman demonstrated last year by firing a 100-kilowatt laser beam steadily for more than five minutes. That’s an impressive achievement by laser standards. The bad news, though, is that this laser doesn’t come in a pretty, prêt-a-porter-sized package.

No, for one thing, this laser has no beam-directing optics, so it can’t target. A bit of a drawback for a weapon. It also has never been operated outside the controlled environment of a laboratory, draws 500 kilowatts of electricity, and is rather inconveniently housed in a shiny metal box about the size of six McMansion-sized refrigerators. Even Godzilla would have a hard time lifting that.

So the question of the day is this: In this age of microminiaturization and nanotechnology, why don’t we have laser pistols, damn it?

Blame this one on the laws of physics.

Lasers don’t generate energy; they convert energy from other sources into light, and in the process, much of the input energy is lost as heat, hampering the amount of damage it can inflict. And what about a power source? Batteries wouldn’t work. A laser gun drawing the 5000 watts of power needed to produce a kilowatt of laser light would need more than a 30-ampere, 120-volt line could deliver, and again, that sort of beam wouldn’t do much damage.

Now, what makes old-fashioned bullets deadly is their momentum. The explosion of gunpowder in a .45-caliber pistol propels the bullet out of the barrel with only 500 joules of energy and the bullet’s momentum keeps it going when it hits a soft target, so it rips through flesh, often with deadly consequences.

Laser light, however, can cause damage only by delivering energy that heats the target. So, say, zapping a mosquito would be no problem—if you could get it to stay still. People, however, are much bigger, and usually try to get out of the way if they feel parts of themselves burning. So in order to kill a human (or an alien) as convincingly as a bullet does, the laser would have to burn a hole through their body by vaporizing tissue, and at the cellular level, that means evaporating water.

As you might recall from 7th grade science, our bodies are mostly made up of water, and evaporating enough of it to make the kind of through-the-body hole we’re talking about would take about 50,000 joules. Now, that’s only about 100-times more energy than the bullet carries. But because the evaporating water would block the beam and dissipate its energy, it would actually take many times more energy than that to truly finish the job.

Lasers may not be able to kill, but they can cause blindness by burning the eye’s light-sensitive retina. However, staring at the sun can do the same, and, sorry folks, the Geneva Convention has been modified to ban blinding lasers. Staring at the sun like an idiot, however? Still allowed. (And, sadly, wouldn’t even get you a Darwin Award these days.)

One thing lasers can do effectively is destroy important military targets, such as rockets, artillery shells, or robotic aircraft which carry fuel or explosives. No evaporating water to interfere there. Just point and track. The laser energy heats the target until it ruptures the fuel tank, or heats the explosive to its ignition temperature and boom! There goes the Death Star. Or, somewhat more mundanely, bang goes the unexploded bomblet lying in an Afghan battlefield before it can kill somebody, a thing that’s actually been done.

Bottom line, however? Lasers just aren’t cut out for killing people.

Still, we do love our sidearms, and if our 25th century heroes and villains aren’t going to be strapping on nifty ray guns or clunky blasters or cellphone-sized phasers, then what sort of weapons could we realistically expect the 25th century to provide?

Well, one possibility would be to adapt a concept originally conceived during the Reagan era “Star Wars” program called “Brilliant Pebbles.” Back then, “Star Wars” researchers were studying a variety of far-out laser weapon ideas, cool stuff like orbiting laser battle stations and X-ray lasers powered by nuclear bombs. But they also looked at slightly less spectacular weapons prospects such as firing high-speed projectiles that would destroy nuclear warheads with the energy of their impact. In other words, hitting a bullet with a bullet.

The idea was called “Smart Rocks,” projectiles that, when fired, could home-in on their targets. Lowell Wood of the Lawrence Livermore National Laboratory then expanded the idea, proposing to use advances in computer technology to build a fleet of satellite-based “Brilliant Pebbles” with sophisticated guidance systems, although, in truth, his “pebbles” were really watermelon-sized missiles.

While that project was shelved after the Cold War ended, the technology trends that inspired Wood have endured and evolved. Computer chips have continued to shrink in size and increase in power, and the sensors needed to recognize targets and guide missiles have likewise become more powerful. So instead of ray guns, why not shrink those watermelon-sized missiles designed for patrolling outer space down to the size of the pebbles they were originally named for and fire them from portable weapons?

The resulting “Brilliant Bullet” would be much more than a lead slug. And much cooler. For instance, it would probably contain a nano-scale propulsion system to guide it along its course and an imaging sensor to photograph people and compare them to an image of the target stored in its memory. (Or, even better, some way to match the person’s genome with that of the target.) It might even unfold wings after emerging from the barrel.

But of course a really “Brilliant Bullet” wouldn’t even require a gun. It could be made larger, the size of a ball-point pen, say, with lightweight wings and a tiny engine that would push it silently through the air. It could be coated with an optical metamaterial, science’s version of an invisibility cloak that bent light around it, making the bullet itself almost impossible to see. It would flicker past people fast enough that they would catch only a ripple in the air, but would move slowly enough to check each person in the area to identify the target. Once it had, it would then ignite its propellant, accelerate to lethal velocity and, bango, good night Seattle. Not as satisfying as firing a gun, maybe, but it would certainly be more accurate. And more deadly.

So, fledgling evil overlords take heart, laser guns may not be possible or practical, but other deadly options are in the works, and the future looks bright for conquest. Optical metamaterials are real. Unmanned aerial vehicles are real. And as for brilliant bullets? Who knows how long before they’re real as well.

All we can say is watch out, Buck Rogers, cause we’re gunning for you.

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Jeff Hecht

Hecht, JeffJeff Hecht is a science-fact writer who contributes regularly to New Scientist magazine and Laser Focus World. His specialties range from lasers and fiber optics to paleontology. His books include Understanding Lasers, Beam: The Race to Make the Laser, Understanding Fiber Optics, and Beam Weapons: The Next Arms Race. He has had short fiction published in venues ranging from Analog and Asimov’s to Nature. More at his web site: http://www.jeffhecht.com

16 Responses »

  1. >>So, say, zapping a mosquito would be no problem—if you could get it to stay still.

    Actually, the tracking problem has been solved (in a controlled setting).

    http://www.youtube.com/watch?v=BKm8FolQ7jw&feature=fvw

    And brilliant bullets (V1.0) exist too. The XM-25 (in trials in Afghanistan) fires a 25mm airbursting, high-explosive round. The rifle is fitted with a rangefinder and cross hairs that auto adjust for wind, temperature, and air pressure. This data is fed to the ammo’s microchip to determine optimal moment for detonation.

    The winged bullet also exists. The one pictured via the link below can be fired from an AA12 shotgun. http://www.defensereview.com/stories/aa-12/FRAG-12%20Projectile_1.jpg

    We better speed up our development of personal forcefields (e.g the Holtzman shield in Dune).

    Interesting article. Thanks.

  2. That’s where the “brilliant bullet” came in. It would just penetrate the shield at a slower speed, then speed up and bounce around inside it. The shield would only block projectiles posessing over a certain level of kinetic energy. (Dune)

  3. There’s a huge gap between the round fired by the XM-25 & a Brilliant Bullet. And there’s good reasons why the XM-25 may not replace the simple grenade launchers in use since the Vietnam War.
    There’s progress being made on a mobile laser weapon(s). Although far too large to be carried by an individual, the goal is a weapon(s) compact & light enough to fit in an armored vehicle or even an aircraft.

  4. There was the “ray gun” that used an ultraviolet laser to ionize the air so it would carry an electric current.

    http://news.bbc.co.uk/2/hi/sci/tech/342188.stm

  5. http://www.projectrho.com/rocket/rocket3l2.html

    Dr. John Schilling is of the opinion that the key to making a laser do bullet levels of damage is pulsing the laser. With this technique, you’ll need a bit over a kilojoule of output energy to reliably incapacitate a human target.

    But your point remains: a laser sidearm would be an expensive, fragile, and energy intensive device compared to a conventional hand gun.

    • Huh, I had lunch on Saturday with Dr. John Schilling (and a few other rocket-related people, at Mojave Spaceport’s diner). Small, laserly world. Slightly nuclear, as well (see http://www.armscontrolwonk.com )

      Have to be careful, the stuff we posted on the net decades ago still haunts us!

      On the main article’s topic –

      Enough said about lasers, other than noting that 500 kw isn’t much power (the typical mechanical power output for battle tank engines is 750-1,000 kw), and the 100 kw throughput solid state laser is only large by tactical aircraft standards. It could be fit in a larger sized battlefield ground vehicle, or a ship, easily.

      On the “brilliant bullets” thread…

      There was some research in the 1970s on heat-seeking antipersonnel micromissiles, the size of a grenade launcher grenade round (4cm diameter, 20cm long or so) not the size of a pen, but it’s been thought of. Back as far as Dune in speculative fiction, at least, as well.

      What one could do today is far in advance of the primitive stuff they thought of then. Combined multispectral visual and IR imaging sensors, laser target illumination detection, millimeter wave seekers, hot-gun IR sensors, etc. MEMS sensor gyros and IMUs, single-chip multichannel GPS sensors.

      On the propulsion front, small batteries and electric motors give potential reasonably quiet hover / cruise modes. Tiny guidance rockets exist for high speed terminal engagements.

  6. There was the “ray gun” that used an ultraviolet laser to ionize the air so it would carry an electric current

  7. The Brilliant Bullet sounds like the bullets from the 80’s Tom Selleck sci-fi movie Runaway. The bad guy, played by Gene Simmons, had this gun that fired miniature guided missiles that locked onto a person’s heat signature.

  8. Lasers intended to cause permanent blindness are banned under the Geneva convention but “Dazzlers”, those intended to cause temporary blindness for the purpose of incapacitating troops fall outside the protocol. Of course what is intended and what actually happens are two differnt things. A dazzled pilot is an incapacitated pilot and is likely to die. From what I can tell from a quick google search is that the Chinese are leaders in this kind of technology. There have been sporadic claims of laser “attacks” upon pilots for a few years now. High powered lasers used by astronomy students to point at stars have dazzled a few pilots in the local training area where I fly. Each of these “attacks” usually involve kids screwing around. Imagine thier surprise when FBI and NIS agents come snooping around. At least one person has been caught. The laser designator mounted on my aircraft was powerful to blind someone…but of course I was following it up with a missile. Illegal? I don’t know. It is difficult to protect your eyes against a laser attack as visors are built to defend against specific frequencies. Not much chance of vaporizing a person but you don’t have toturn a person into a puddle of goo to ruin his day.

  9. http://en.wikipedia.org/wiki/Electrolaser

    Not quite what would work, either but a step in the right direction

  10. The efficiency of military lasers really depends on how much electrical power you can generate on the battlefield. This is why the required volume for equipment for a Megawatt-level weapon is a Boeing 747. This is still quite weak though, as a tonne of steel requires around over a Gigajoule of energy to get from room temperature to melting point. For truly devastating laser weapons, the power sources would be the kind found on large ocean-going naval vessels, such as 200-300 MW reactors on Aircraft carriers.

  11. Laser pistols are not as far-fetched as some believe. If all you are looking for is efficiency, an arrow can cause lethal injuries with much less energy than a bullet. A rifle bullet carries 500 times the energy of an arrow. The real problems are finding a power source that can release the intense bursts of energy needed by a ray-gun and creating compact and efficient lasers that are suitable for handguns.

    A series of laser pulses can cause vapor explosions, creating an expanding cavity and blasting deep through meat, gristle, and bone to cause lethal injuries. Using this technique, a laser rifle would blast deep through a human using only a few kilojoules of input energy, similar to the energy of a rifle bullet.

    A mega-watt range laser could burn a 3cm hole 10cm deep into flesh with 250 kilojoules. Not to mention that vaporized water will expand and rip surrounding tissue apart. Flesh would simply cook until it bursts…

    Assuming you need 250 kilojoules to blast through flesh, a battery pack weighing one kilogram with the energy density of TNT will provide enough energy for 18 shots. The laser is probably more deadly than a bullet- most bullets don’t make 3cm holes in people. If a pulsed laser that can kill with 5 Kj of energy is used, the battery pack will hold 900 shots.

    A real infantry laser weapon would likely fire high-energy bursts of laser light with 2+ kilojoules of energy. The intense super-heating will cause the water in flesh to boil and explode into steam, creating messy wounds. Modern portable power sources and lasers cannot release a few kilojoules of energy in a quick pulse- but future tech will, someday. Real lasers will not be the neat, clean weapons portrayed in countless SF shows and movies- real laser weapons will be deadly and scarring. Imagine some sort of beam burning through your flesh, or a quick pulse pumping enough heat into your flesh to cause the tissue to burst into steam and gore.

    Bottom line is, if someone directs enough energy at you, be it laser or bullet, you will die. Can a man-killing laser be a size a human can carry? Yes, there is no reason why not- but modern laser and battery tech is not able to create a convenient hand held weapon. The amount of energy a laser pistol would need is not ridiculous- we carry around similar amounts of energy in our laptops and cars. Given future developments in laser and battery tech, it will be possible to create the intense pulses of energy needed by a portable laser weapon.

    Even if laser pistols are a far-off development, a rifle-sized solid state laser weapon might be nearer in our future. Heat coils around the barrel would dissipate heat after firing, and the weapon would be connected to a backpack generator. The user might have to wear a thermal protection suit, however.

    Bullets are not necessarily instantly lethal. Unless they hit a vital organ, incapacitation is not reliable- and many humans have carried on with incredible injuries, even if they die minutes later. It doesn’t take much time for someone to cause irreparable harm, even if they are mortally wounded. Just ask ballistics experts. This is why self-defense gurus are so concerned about caliber. I suspect most people will die rapidly if they are cut in half by a megawatt laser.

    As a closing note- a 5 megajoule laser pulse would blast a person to pieces. No need to worry about the effectiveness of various calibers now… “evil laugh”.

    • I think if you were to do your own research, and have actually read the article, you would know that THIS article is right…

      • Ha ha, well, the stuff we write back ages ago just hangs around the web to haunt us, doesn’t it… ;-)

        But I have actually read the article. At least twice. First the author points out that while laser technology has advanced in the last fifty years to the point that the military is experimenting with high-energy lasers as weapons, said “laser cannons” are bulky, heavy, fragile, and energy intensive devices that dwell in laboratory environments, and have not yet been demonstrated under anything approaching battlefield conditions.

        Then the author goes on to point out that, unlike a projectile, a beam of laser light does not carry much momentum and thus tends to heat the surface of things rather than ripping through like a pistol bullet. To do bullet levels of damage we have to vaporize all the meat in the path of the beam, a process the author calculates will require 50,000 joules, assuming we simply have to put in enough energy to vaporize all the water in human flesh. In reality that expanding steam will blow back into the beam and tend to block the beam, requiring even more energy.

        The conclusion? Lasers are not particularly cut out for killing people compared to the efficiency of a bullet, though the aforementioned “laser cannons” could heat a projectile or aircraft containing flammable fuel or explosives until it goes “pop” without burning a hole through it. Lasers can blind people easily, but deliberate laser blinders are illegal under the Geneva conventions (thankfully!!).

        Finally, the author switches topics to suggest that, instead of “ray guns”, future warriors could carry guns firing small “smart bullets” capable of seeking their targets, or even launch tiny assassination drones that can hunt for their victims and turn invisible using metamaterials.

        This is all more or less correct, of course. I must admit that I prefer to reserve judgement on invisible personal hunter-killer drones, considering that modern metamaterials only work in a few frequencies of light. Admittedly they are very cool. But does seem like trading one magic tech for another. But yeah, laser pistols probably aren’t practical in the light of real physics and technology constraints.

        There is one (rather gruesome) antipersonnel application of the laser that Jeff Hecht didn’t mention- lasers don’t have to burn holes through people, instead, they can be used as long-range radiant flamethrowers to burn skin and ignite flammable substances. According to this web page, this would only take about 15 joules per square centimeter… if I were to do an in-depth analyses of antipersonnel lasers i would have to do better research than can be done on the web, of course.

        Then again, it might be a little embarrassing to drag your new six million dollar death ray out onto the battlefield only to find out that it is somewhat ineffective on people wearing light-colored flame retardant clothing, and stops working well in the rain. :-) Bottom line? Laser weapons may be real, but they just aren’t as practical as bullets.

  12. Well what about if we use some nuclear substance which is similar to a ruby and use it instead of the laser ruby? It would constantly produce gamma rays and amplify them and we can install ‘smart glass which is a reflector until you pass electricity through it instead of the partial reflector, so we can fire that built up radiation wherever and whenever we like.

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