Hypothetical laser gun

[factotum]

Assuming a constant time to intercept, it takes the exact same amount of force to accomplish that goal whether you're moving at 0.1 m/s or 0.1c.

I think his point is that time to intercept will vary depending on your speed vector in the direction of the enemy ship. If you're cruising toward them at high speed you will have less time to detect incoming fire and take evasive action. As I pointed out, though, you're not likely to be doing that if there's a known enemy ship in the area.

[Son of A Lich!]

One issue with lasers is which wavelength to use. Moat people think about IR, UV, and visible light lasers, but you can theoretically lase across the entire EM spectrum.

Microwave lasers should be interesting, and I'd be interested to know what a radio laser would do to electronics. One of the important aspects this is thay as you use shorter and shorter wavelengths the light wave itself becomes more damaging. So you need to produce less light, although the overall energy input will probably remain similar.

If I'm not mistaken, weren't Microwave lasers used previously for something like a week in Iraq before being outright banned as unholy weapons for warfare?

My understanding of the weapon was that it was intended to create uncomfortable heating that could pierce structures without destroying them. The microwaves would penetrate the body and react with water to make heat, so it wouldn't effect structures or vehicles and it wouldn't start fires in arid environments.

Only to then discover that focus fire from, say, a squad of Marines firing in unison would essentially bake a human from the insides and they never actually saw combat.

I think it was called a Phazer, because it was supposed to be nonlethal... but gods, yes, they were. I'll see if I can find an article on them.

[LordEntrails]

If I'm not mistaken, weren't Microwave lasers used previously for something like a week in Iraq before being outright banned as unholy weapons for warfare?

My understanding of the weapon was that it was intended to create uncomfortable heating that could pierce structures without destroying them. The microwaves would penetrate the body and react with water to make heat, so it wouldn't effect structures or vehicles and it wouldn't start fires in arid environments.

Only to then discover that focus fire from, say, a squad of Marines firing in unison would essentially bake a human from the insides and they never actually saw combat.

I think it was called a Phazer, because it was supposed to be nonlethal... but gods, yes, they were. I'll see if I can find an article on them.

Lasers were used in Iraq. At least in two varieties I know of. One was used, the other was deployed but not used.

According to a 2005 Wired article

Among the simplest forms are inexpensive, handheld lasers that fill people's field of vision, inducing a temporary blindness to ensure they stop at a checkpoint, for example. Some of these already are used in Iraq.

https://www.wired.com/2005/07/beam-i...-there-scotty/

And Project Sheriff (that quote is for Afghanistan, not Iraq);

It was briefly deployed in Afghanistan in 2010, but reportedly withdrawn without having seen action,

https://www.defenseindustrydaily.com...h-hoops-02987/

As for the international legality of directed energy weapons;

In order to limit unnecessary harm, the UN General Assembly voted to prohibit the anti-personnel use of incendiary weapons against combatants in 1972.[3] In 1977, Article 35 of the Geneva Conventions prohibited weapons that cause “superfluous injury or unnecessary suffering.”[4] To meet this intent while taking advantage of today’s advanced technology, the Law of Armed Conflict should be amended to allow for new directed-energy weapons that intentionally minimize suffering. Experts suggest that an anti-personnel laser must direct several megawatts of energy at a soldier to burn them.[5] For the U.S. military to lawfully use directed-energy weapons against combatants would require the laser to generate even more lethal energy, enabling an instant incineration that does not cause unnecessary suffering.

https://www.realcleardefense.com/art...ns_113641.html

Demo and discussion with laser and microwave systems for anti-drone activities; https://www.military.com/video/high-...hoots-down-uav
(Note the X Box controller?)

And since we are talking lasers (and anti-drone); https://www.military.com/video/direc.../4557815995001

The US Navy is currently deploying 150kW laser; https://www.military.com/daily-news/...avy-ships.html

The US Army has also deployed lasers and the US Air Force has awarded another contract for a deploy-able Phaser

the Air Force has contracted with Raytheon for a $16 million prototype Phaser high-powered microwave counter-drone system

; https://www.military.com/daily-news/...nd-phaser.html

[The Random NPC]

The speed does matter. Detecting a cold bunch of very small objects is non-trivial. Rapid course changes over “short” distances is energy and fuel intensive. The relative speed of the ship and the projectiles matter due to how difficult it would be to detect them and then maneuver around them in time.

I remember reading an article from some science website that asserted that you don't have to detect the projectile, just the firing of the projectiles. That will give you enough information to determine the flight path of the projectile and avoid or intercept it. And if it's capable of changing course, you'll detect that too. Basically, unless you have a launch mechanism that doesn't generate heat, you're projectile needs to be really fast, really close, or disguised as a nonprojectile.

[LordEntrails]

I remember reading an article from some science website that asserted that you don't have to detect the projectile, just the firing of the projectiles. That will give you enough information to determine the flight path of the projectile and avoid or intercept it. And if it's capable of changing course, you'll detect that too. Basically, unless you have a launch mechanism that doesn't generate heat, you're projectile needs to be really fast, really close, or disguised as a nonprojectile.

You don't "need" to know projectiles vector, but it certainly helps. Otherwise you are assuming they are aiming where you are going to be. But maybe they have aimed not for where your vector takes you, but where they think you will move to avoid their projectiles. It becomes a guessing game with odds.

[5crownik007]

Before we do talk about hypothetical laser guns, let's talk about actual directed energy weapons.
1. Microwave Active Defense System.
A vehicle mounted system which uses a big dish to heat your skin and activate nerve receptors, but not leave any actual damage. I haven't heard about it being used by police, probably due to cost reasons, but I imagine that it would be really nice to have one of these to break up a riot.
2. XN-1 Laser Weapon System
Of course, it's the navy with the cool laser gun. It's a 30kW laser which can detonate enemy munitions and damage enemy watercraft. Supposedly it can engage helicopters by damaging vital systems. It can also disable sensors, and can also blind people(but that's illegal). It can kill UAVs in a matter of seconds.
3. ZM-87
Norinco made a blinding laser weapon, that would disable sensors and blind enemies(after all, you can hardly fight if you're blind). It was made illegal by a UN treaty on the use of blinding weapons. Not much else is known about it.

Now, hypothetical laser guns like in the movies don't really have a lot of application. firearms have had their niche for hundreds of years, and it doesn't seem that they're going to be displaced by heavy, difficult and finicky laser guns. However, laser guns do have application in places where firearms and explosives don't.
Nonlethal weapons. Electrolasers are a promising candidate for being able to stun people from long distances (after all, they're effectively tasers with ionized are for wires). Anti-optics. Lasers can effectively blind enemy sensor equipment by burning out sensitive parts or heating them up. It might not necessarily be lethal to a human, but very damaging to a camera or sensor.

[factotum]

You don't "need" to know projectiles vector, but it certainly helps. Otherwise you are assuming they are aiming where you are going to be. But maybe they have aimed not for where your vector takes you, but where they think you will move to avoid their projectiles. It becomes a guessing game with odds.

A guessing game with pretty *good* odds, to be fair--to all intents and purposes they'd be firing at some random spot in space if they're not aiming at your actual vector, unless they have some inside knowledge of what course change you're likely to make. Which, of course, is why any sensible captain would make his manoeuvres entirely random.

[The Random NPC]

You don't "need" to know projectiles vector, but it certainly helps. Otherwise you are assuming they are aiming where you are going to be. But maybe they have aimed not for where your vector takes you, but where they think you will move to avoid their projectiles. It becomes a guessing game with odds.

That's what I mean, the article asserted that the act of firing a projectile gives you all the information you need to determine the projectile's vector. You don't actually need to be able to detect the projectile after that. I don't know how accurate that is though.

[LordEntrails]

Before we do talk about hypothetical laser guns, let's talk about actual directed energy weapons.
1. Microwave Active Defense System.
A vehicle mounted system which uses a big dish to heat your skin and activate nerve receptors, but not leave any actual damage. I haven't heard about it being used by police, probably due to cost reasons, but I imagine that it would be really nice to have one of these to break up a riot.
2. XN-1 Laser Weapon System
Of course, it's the navy with the cool laser gun. It's a 30kW laser which can detonate enemy munitions and damage enemy watercraft. Supposedly it can engage helicopters by damaging vital systems. It can also disable sensors, and can also blind people(but that's illegal). It can kill UAVs in a matter of seconds.
3. ZM-87
Norinco made a blinding laser weapon, that would disable sensors and blind enemies(after all, you can hardly fight if you're blind). It was made illegal by a UN treaty on the use of blinding weapons. Not much else is known about it.

See the links I posted above. 30kW laser has been replaced by a 150kW laser being deployed aboard a US Navy ship this year.
The ZM-87 is what I believe was also linked above, and it was (is?) used in Iraq.

[Strigon]

Now, hypothetical laser guns like in the movies don't really have a lot of application. firearms have had their niche for hundreds of years, and it doesn't seem that they're going to be displaced by heavy, difficult and finicky laser guns. However, laser guns do have application in places where firearms and explosives don't.

I understand all those issues, and I agree that the future will probably never be laser handguns, but I'd be very careful with that line of thinking.
If there's one thing we've learned about technological progress, it's that things which appear to have only specialized applications, and will never replace an existing technology, have a tendency to do exactly that. This is especially true when one of the hinderances is weight/bulk. Sure, lasers will always require a lot of power and a lot of cooling, things which, as far as we're aware, are always going to be bulky. We have only the most wild guesses how to cool down a handheld laser that's good enough for military use, sure, but things change faster than we like to think.

After all, for quite a while, bows had their niche. When firearms first showed up, they were pretty lackluster in terms of actually causing damage. It certainly didn't seem like bows were going to be displaced by expensive, inaccurate, slow-firing matchlocks.

[factotum]

After all, for quite a while, bows had their niche. When firearms first showed up, they were pretty lackluster in terms of actually causing damage. It certainly didn't seem like bows were going to be displaced by expensive, inaccurate, slow-firing matchlocks.

The difference there, though, is that guns *did* have advantages over bows in some ways. They were easier to use and aim, and they also didn't require the same degree of physical strength, all of which made them good tools to give the unwashed masses while you kept your elite archers. Then, as they improved, the unwashed masses took over and the elite archer corps disappeared.

A laser, however, doesn't really have a major advantage over a firearm in any department, at least so long as you're talking about earthly combat. The "instant hit" of the beam really isn't significant over the sort of ranges that typical engagements occur at, and over really long ranges the scattering effect of the atmosphere reduces their accuracy and power significantly, to the point you might as well use a conventional sniper rifle. Absent any advantage to their use, there just isn't the urge to fix their many issues.

[Tvtyrant]

Guns actually opened a bit of a renaissance for bows. Guns pierced body armor, so the armor got thicker and covered less of the body until it was abandoned altogether. Bows had higher rates of fire, but could not penetrate armor as well. This meant that mass adoption of guns made individuals more vulnerable to bows, which peaked with the Zulu wars where the British could have really used some decent armor and swords but had abandoned them entirely.

[Son of A Lich!]

The difference there, though, is that guns *did* have advantages over bows in some ways. They were easier to use and aim, and they also didn't require the same degree of physical strength, all of which made them good tools to give the unwashed masses while you kept your elite archers. Then, as they improved, the unwashed masses took over and the elite archer corps disappeared.

Right, what's that old adage? "If you want an excellent archer, you start with his great grandfather", something like that?

[LordEntrails]

Lasers do have advantages over explosive ballistic weapons (aka firearms). Not sure they will ever been sufficient to motivate the development of the technology so it can outclass firearms though.

[Strigon]

The difference there, though, is that guns *did* have advantages over bows in some ways. They were easier to use and aim, and they also didn't require the same degree of physical strength, all of which made them good tools to give the unwashed masses while you kept your elite archers. Then, as they improved, the unwashed masses took over and the elite archer corps disappeared.

A laser, however, doesn't really have a major advantage over a firearm in any department, at least so long as you're talking about earthly combat. The "instant hit" of the beam really isn't significant over the sort of ranges that typical engagements occur at, and over really long ranges the scattering effect of the atmosphere reduces their accuracy and power significantly, to the point you might as well use a conventional sniper rifle. Absent any advantage to their use, there just isn't the urge to fix their many issues.

Lasers do have advantages over firearms. It's why they're used, albeit in a niche role.
Zero recoil, practically infinite muzzle velocity, negligible projectile drop, and far less (or no) moving parts are all desirable qualities in a weapon.

[factotum]

Lasers do have advantages over firearms. It's why they're used, albeit in a niche role.
Zero recoil, practically infinite muzzle velocity, negligible projectile drop, and far less (or no) moving parts are all desirable qualities in a weapon.

Assuming we're still talking about lasers as hand weapons (I acknowledge that vehicle-mounted units may have some uses), I already said that the infinite muzzle velocity and negligible projectile drop are largely irrelevant over the distances combat takes place on Earth. Zero recoil is lovely, but if your weapon weighs 100 pounds that pretty much loses any handling advantages the lack of recoil offers. Lastly, a laser doesn't have zero moving parts; any reasonable one requires a honkin' great cooling system, and even the parts which don't move are electronic and thus can fail anyway. Once it has failed, I'm pretty sure the average soldier in the field isn't going to have the knowledge to strip down and fix the thing, whereas that's something they totally can do with conventional weapons.

[LordEntrails]

Let's see...
Size, well technology has the chance of resolving that. Not with anything we have today, but then again, early computers used cathode ray tubes until something better was invented.
Cooling, again, an issue today, but future power sources and emitting devices might not present such challenges. Think of the light bulb. Incandescent give off what, 98% energy as heat (thermal & IR) and 2% as light? Halogen was almost twice as good at 96/4%. And then we have fluorescent at 92/8%. Now we have LED's at what 80/20%?

So yea, we don't have the technology today for a practical hand-held laser weapon. But, in 100 years? I wouldn't doubt it. Though it's also likely that we won't, but pretty likely we will have some sort of directed energy weapon.

[veti]

What theoretical advantages do directed energy weapons have over kinetic weapons?

If you're trying to shoot down something over a heavily populated area, it's a big advantage to have a weapon that doesn't drop its spent projectiles back to earth. This was quite a big issue at Gatwick Airport last December.

Though personally I thought a highly directed EMP would be more effective than just trying to burn it with raw power.

[factotum]

If you're trying to shoot down something over a heavily populated area, it's a big advantage to have a weapon that doesn't drop its spent projectiles back to earth. This was quite a big issue at Gatwick Airport last December.

And the target just magically vanishes and doesn't come crashing to the ground when you shoot it?

[Telok]

And the target just magically vanishes and doesn't come crashing to the ground when you shoot it?

It was going to do that anyways no matter what you hit it with.


Of course depending on what you're shooting at you can debate what sort of things you want to come down in one chunk or many.

[Lapak]

Hmm, I wonder if using bomblets and/or MIRV technology would work - a single missile to get the warhead into the right area, then the warhead separates into an optimal spread pattern of proximity triggered bomblets.

Alternately, take a leaf out of the Macross series and have mini seeker missiles carried by a single larger missile.

IIRC the ships in the Honor Harrington universe use a variation on the first answer that mixes both - missiles with the ability to adjust course and carry defensive measures get relatively close to the target, then go off as an array of bomb-pumped X-ray lasers in a spray once they are within a range where beam dispersal isn't as much of an issue to defeat super close-range defenses.

(The series is not sensible about space combat in too many ways to list, but this parallel I thought was worth mentioning.)