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[Shadowlord]

Watching the video, you can see that it is indeed several seconds (assuming the video wasn't sped up).

P.S. Fallout doesn't follow real-world physics, so realism is irrelevant.

[Amperzand]

Assuming it doesn't overheat too quickly, and is running directly off the ship's power plant rather than pre-charged capacitors, effectively as long as they want. The test footage I've seen pretty much had it firing until it was no longer necessary to fire.

[Stirk]

Watching the video, you can see that it is indeed several seconds (assuming the video wasn't sped up).

P.S. Fallout doesn't follow real-world physics, so realism is irrelevant.

Its not like I can see the laser . I mean, I can see the fire, but it *could* be firing in microsecond bursts or something. At 50,000 J/s, it would only need a hundredth of a second for the energy involved for the energies necissary for our purposes.

And I know, I love it anyway . I think they just managed to hit a pet peeve of mine. Pretending to make something more realistic when its actually making it less realistic is super annoying :V. So I just wanted to know if lasers would/wouldn't have recoil. I mean, it would be like "fixing" the recoil on the guns by having them throw enemies around like water from a sprinkler :X.

Assuming it doesn't overheat too quickly, and is running directly off the ship's power plant rather than pre-charged capacitors, effectively as long as they want. The test footage I've seen pretty much had it firing until it was no longer necessary to fire.

Looking at it, apparently they have it hooked up to a video-game like system, and a :

Composed of commercial laser components and proprietary Navy software, it is powered and cooled by a "skid" through a diesel generator, separate from the ship's electrical systems, giving greater efficiency relative to power provided of 35 percent

Apparently having it connected to its own generator improves efficiency.

[Amperzand]

Interesting. I'm not sure why that would be.

[Gigaz]

There is one thing to keep in mind with Laser weapons.

If you fire a bullet at someone, you essentially use the momentum of the bullet to locally destroy the tissue, while the overall energy of the bullet is not all that high and could only increase the temperature of the body part by some millikelvin.

In a Laser weapon however, the locally concentrated energy of the beam vaporizes a small part of the target, leading to a hopefully destructive explosion. The locally transferred energy is the important quantity, whereas the photon momentum is not.

And this is why a Laser weapon has no noticeable recoil.

[Erkki]

Its also important where the vaporization occurs... Say, in someones eyes:

https://en.wikipedia.org/wiki/ZM-87

Also that very likely is not the only infantry-portable product in use. Laser weapons have been in use for decades and no, even the heaviest dont have meaningful if even measurable recoil.

Boeing also has that cute anti-drone laser gun that fits in a trunk together with its tripod and batteries.

[Tiruin]

Many awesome people have detailed the very good point about laser weaponry here (along with very good details on the answer). 'Recoil' as I understand it is the reverse force which occurs after launching a physical projectile--technically there 'wouldn't' be, because  considering what a rifle or pistol size to the body or position of firing, your tactile senses won't pick up on the force as something 'backwards' from the firing point.

But if you consider technicalities of a reverse force existing from the generation of a laser to create recoil: Technically nope. (Actually Yes, but in a 'people feeling it', technically nope see below)


~Edit~
To clarify: There's a threshold of 'feeling' thanks to this person, as in when you can feel a difference between objects or a force+object which provides the information between the 'lack of felt recoil' [ie Rifle/Pistol in hand or braced by the shoulder], and 'I can feel recoil'. When I said 'technically nope' up there, I'm assuming the energy being used by a laser rifle or pistol (though...I think I'm assuming a very different picture than most of what the thread says o_O {As in, I'm imagining those laser tag toys?}).
They do have recoil. It depends if it is felt by the amount of energy.

[10ebbor10]

We can calculate recoil easily. Let's assume we want a laser gun with the same amount of recoil as a pistol. Picking a bullet at random, I find a weight of 8.04 grammes and a speed of 360 m/s.

The formula for the momentum of light is easy. P=e/c.

The result is 860 MJ of energy, 6 orders of magnitude more than that of the bullet. Suffice to say, recoil would not be a problem.

http://m.wolframalpha.com/input/?i=8.04g*%28360m%2Fs%29*speed+of+light&x=0&y=0

https://en.m.wikipedia.org/wiki/9×19mm_Parabellum

[Sheb]

The LAWS fire 50 kW in the infrared. That's 50000 J/s. Now, light does have momentum, because while its rest mass is zero, it does have energy so it has mass. E = mc², so m=E/c². Momentum (p) is mass time velocity, so p=mv = (E/c²)*c = E/c

So your LAWS laser create light with (5*10^4)/(3*10^8) kg*m/s of momentum per second. Since momentum is conserved, your LAWS' momentum (or the ship it is attached to) will have its momentum shifted in the other direction. Now, change of momentum over time is a force, so we can express it in Newton. When fired, your laser create recoil of 0.00016 Newton. That's force equivalent to the weight of 0,016 grams. (Which is a lot more than I expected).

So yeah, there is technically recoil. But I think it's more realistic to ignore it.

Edit: Kind of ninjaed by 10ebbor10.

[andrea]

so, you have recoil but by the time the recoil of your hand held device becomes significant, you had to link it to a nuclear power plant and you are likely melting the surrounding area due to energy loss?

a laser gun with the recoil of a battleship main gun could easily be worthy of a xkcd what-if , in terms of ability to damage the planet. ( haven't done the reserch and math behind it)

[wierd]

We can calculate recoil easily. Let's assume we want a laser gun with the same amount of recoil as a pistol. Picking a bullet at random, I find a weight of 8.04 grammes and a speed of 360 m/s.

The formula for the momentum of light is easy. P=e/c.

The result is 860 MJ of energy, 6 orders of magnitude more than that of the bullet. Suffice to say, recoil would not be a problem.

http://m.wolframalpha.com/input/?i=8.04g*%28360m%2Fs%29*speed+of+light&x=0&y=0

https://en.m.wikipedia.org/wiki/9×19mm_Parabellum

At those energies, you start to bump heads with the restraints I mentioned on page one.  That's why I mentioned them. Basically, when you start emitting that much laser energy that you get bullet like recoil from the radiation pressure, your beam will self-refract and other nasty things. Basically, you cannot make a laser weapon that will do this.

Certainly not in a handheld form factor.

Here's a link to a pulp science article which provides both a link to the source research and give the derived hard limit on laser energy before spontaneous QED breakdown happens and the beam instantly becomes incoherent.

http://theastronomist.fieldofscience.com/2010/08/limits-on-lasers.html

According to the article, that hard limit is 10 to the 25 W/cm.

IIRC, the bloom limit in atmosphere is substantially lower, closer to 10MW. (there's a reason why LaWS is a 50KW pulsed laser!!)

In short, a laser pistol capable of producing recoil equal to a conventional pistol will cause the air in front of the gun to bloom with astounding energy, equal to a small explosion, and will probably cook/kill the soldier firing it. Only a tiny portion of the beam energy would make it to target.

For practical reasons, such a gun is not useful as a sidearm, and can be discounted from being reasonably considered.

Again, that was the point I was delicately trying to convey.

[smirk]

Folks, I think you're all missing the most important part of this thread:

I mean, it would be like "fixing" the recoil on the guns by having them throw enemies around like water from a sprinkler :X.

Why doesn't this Fallout mod exist yet? It shouldn't be too difficult; you'd need to attach a script to all firearms that would ragdoll and shove their wielder backwards upon firing, and also remove all melee weapons to force gun use.

Just imagine pitched battles between bandit clans, drifting like tumbleweeds across the wasteland...

[NullForceOmega]

Failure to read, disregard.

[Sheb]

Wierd: It could make a nice weapon if used in space though.

[wierd]

I covered that in my very first reply.  "maybe a starship weapon..."

The thread is about sidearms though.  You dont want something akin to detonating a stick of dynamite anywhere near you-- but that is exactly what such a weapon would be like.