Would a laser gun recoil? - Polidicks

Need either Johnny or aVon in this shit, sort this out.

[QUOTE=Killuah;22098431]Oh my god there IS NO RECOIL AS THE PHOTONS AREN'T PROPELLED BY A VECTORED FORCE.[/QUOTE] Photons have momentum and are only allowed to exit the device if they travel in the right direction. If the device didn't gain momentum in the contrary direction, your momentum wouldn't be conserved. [editline]01:40PM[/editline] The photons exert uneven radiation pressure on the walls of the device because they're allowed to leave through one of the walls.

A normal Pistol creates recoil because the explosion pushes both bullet and gun away from each other. How does a laser create its "bullet"? I don't think it would force the gun the other direction.

Operational advantages Laser weapons could have several main advantages over conventional weaponry: Laser beams travel at the speed of light, so there is no need (except over very long distances) for the laser weapon's user to compensate for target movement when firing over long distances. Consequently, evading a laser after it has been fired is impossible and any attempts at evasion would have to take place while the laser is still aiming. Light's short transit time also nearly eliminates the influence of gravity, so long range projection does not require compensation for such. Other aspects such as wind speed can be ignored entirely. Lasers can change frequency to provide an active area that can be much smaller and theoretically much larger than projectile weaponry. Depending on power source technology, laser weapons could essentially have limitless ammunition. [B]Because light has a practically nil ratio (exactly 1 / c) of momentum to energy, lasers produce negligible recoil.[/B] The operational range of a laser weapon can be much larger than that of a ballistic weapon, depending on atmospheric conditions and power level. From Wikipedia.

[QUOTE=burninplaces;22099216]Operational advantages Laser weapons could have several main advantages over conventional weaponry: Laser beams travel at the speed of light, so there is no need (except over very long distances) for the laser weapon's user to compensate for target movement when firing over long distances. Consequently, evading a laser after it has been fired is impossible and any attempts at evasion would have to take place while the laser is still aiming. Light's short transit time also nearly eliminates the influence of gravity, so long range projection does not require compensation for such. Other aspects such as wind speed can be ignored entirely. Lasers can change frequency to provide an active area that can be much smaller and theoretically much larger than projectile weaponry. Depending on power source technology, laser weapons could essentially have limitless ammunition. [B]Because light has a practically nil ratio (exactly 1 / c) of momentum to energy, lasers produce negligible recoil.[/B] The operational range of a laser weapon can be much larger than that of a ballistic weapon, depending on atmospheric conditions and power level. From Wikipedia.[/QUOTE] One other thing; it could be completely solid state, even the trigger could be a piezoelectric device. Hey presto, no jams. Ever.

A laser should not generate any recoil if it is not using physical forces to accelerate photons. Lasers work by starting a reaction that generated the first few photons of the laser. These photons excite the electrons of the atoms of the gas in the laser chamber, and when the electrons revert back to their original states, and release a photon of the same type in the same phase. This process builds up a large number of photos that are all in phase, and a mirror that reflects almost all of the light that hits it allows some of the photons to escape, which produces the laser dot that we see. In this reaction, no forces are exerted on the photons. Therefore there should be NO RECOIL since neither the gun or photons are exerting forces on each other.

[QUOTE=Mattz333;22103165]A laser should not generate any recoil if it is not using physical forces to accelerate photons. Lasers work by starting a reaction that generated the first few photons of the laser. These photons excite the electrons of the atoms of the gas in the laser chamber, and when the electrons revert back to their original states, and release a photon of the same type in the same phase. This process builds up a large number of photos that are all in phase, and a mirror that reflects almost all of the light that hits it allows some of the photons to escape, which produces the laser dot that we see. In this reaction, no forces are exerted on the photons. Therefore there should be NO RECOIL since neither the gun or photons are exerting forces on each other.[/QUOTE] The force is exerted on the rear mirror. If no photons escaped, the collision would average out with no net force. But when they escape out the front mirror, the transfer of of momentum between the photons and the mirrors is asymmetric, making the laser recoil.

Time to post this on the xkcd forum and start a year long argument.

Someone there probably has access to the equipment required to test it

do you guys realize the physical impossibility of making photon weapons that would do any significant damage

[QUOTE=Protocol7;22105577]do you guys realize the physical impossibility of making photon weapons that would do any significant damage[/QUOTE] I'm not aware of any physical reason why one couldn't make a laser strong enough to function as a weapon [editline]09:47PM[/editline] Economical, perhaps. Ethical too. But not physical.

We already have though. I forget the name, but the US military put a laser on a 747 and pewpew at missiles.

[QUOTE=Protocol7;22105577]do you guys realize the physical impossibility of making photon weapons that would do any significant damage[/QUOTE] I agree. It would consume so much energy and would do so little damage. Taking down a missile is one, piercing heat resistant plating is another. Besides, if you'd polish the armor it instantly becomes unaffected by light based weapons. Which is why Russians used a cannon on their satellite. Clever please.

[QUOTE=sami-pso;22110881]I agree. It would consume so much energy and would do so little damage. Taking down a missile is one, piercing heat resistant plating is another. Besides, if you'd polish the armor it instantly becomes unaffected by light based weapons. Which is why Russians used a cannon on their satellite. Clever please.[/QUOTE] I agree, except for the polished armour thing. Reflective surfaces are never 100% reflective, and will only be reflective for certain wavelengths. Because it won't be 100% reflective, a good portion of the energy will be absorbed, damaging the armour and making it lose it's reflectiveness, making it absorb more energy, lose more of its reflectiveness, etc. It won't take more than a few seconds until it's absorbing as much energy as if it wasn't polished in the first place. Besides, if you're using a laser of variable frequency you can just switch to a frequency not reflected by the armour. That said, you're right that they wouldn't be great weapons, especially in an atmosphere. The only place they'd be a good choice is in space. Anything else in space you can see coming and avoid, but not lasers. You also don't have the problems of atmospheric blooming and diffusion and that fact that high powered lasers would just cause the air in front of the muzzle to explode due to the immense energy it'll absorb.

It's unlikely that the vehicle is a solid ceramic block. Aim for the strategic targets; your weapon cannot miss. [editline]02:17AM[/editline] And use ionizing frequencies just to show them that no matter what, in the end they'll lose

[QUOTE=ThePuska;22105923]I'm not aware of any physical reason why one couldn't make a laser strong enough to function as a weapon [editline]09:47PM[/editline] Economical, perhaps. Ethical too. But not physical.[/QUOTE] you'd have to create enough energy to be able to make a laser that does more than just burn things because on a battlefield a laser is easy to dodge because it's easy to see and you only suffer burns and the problem is depending on the color of light if it's monochromatic or not is if it IS monochromatic, easy to reflect. if not, still easy, just get a giant ass mirror plus how would you give individual soldiers enough energy to sustain powerful photon weaponry for any significant amount of time? I don't think it's possible unless we synthesize a new element that's full of energy

Also related: [url]http://en.wikipedia.org/wiki/Active_Denial_System[/url]

[QUOTE=Str4t0s;22084169]Fun fact, lasers in star wars are not realistic, because you cannot see lasers in space.[/QUOTE] The lasers in Star Wars aren't lasers.

It has momentum, it has recoil, but I doubt anyone would be able to notice it.

Well, good thing .22LR has unnoticeable recoil as is. [editline]06:30PM[/editline] [QUOTE=fskman;22110555]We already have though. I forget the name, but the US military put a laser on a 747 and pewpew at missiles.[/QUOTE] And on the back of Humvees.

Why do we care again?

However, wouldn't a laser have an extremely small amount of reverse force due to lasers being based off the emission of radiation? Granted, the amount would be so small it would be unnoticeable in any area but one without gravity. Even then, the amount of force would be so small that it would barely move. Since every action has an equal and opposite reaction, wouldn't the force of the emitted protons cause a reverse force, regardless of how small, on the laser?

Actually it wouldn't have any recoil because the energy is directed in one direction instead of scattering around like a bullet

My laser pointer doesn't have recoil

[QUOTE=Str4t0s;22084169]Fun fact, lasers in star wars are not realistic, because you cannot see lasers in space.[/QUOTE] Actually, you can see LASERs in space because they are a light wave. Light waves are electromagnetic and can travel through a vacuum. If this wasn't the case for light waves, we wouldn't be able to see the Sun from Earth. Overall, this was a very dumb thing to say. I capitalize LASER, because it is an acronym, and Google Chrome must not respect the use of acronyms because they are saying it is misspelled.

[QUOTE=duce2231;22145819]Actually, you can see LASERs in space because they are a light wave. Light waves are electromagnetic and can travel through a vacuum. If this wasn't the case for light waves, we wouldn't be able to see the Sun from Earth. Overall, this was a very dumb thing to say. I capitalize LASER, because it is an acronym, and Google Chrome must not respect the use of acronyms because they are saying it is misspelled.[/QUOTE] He's right. You wouldn't be able to see a laser in space unless is fired directly at your eyes (so you wouldn't see much anyway before your face melts.) The reason we don't have to shine a laser or a torch in our eyes to see it in the atmosphere is because the air molecules scatter a small proportion of the light in all directions, allowing us to see the beam going along its path.

[QUOTE=Protocol7;22089104]Either way, a "laser" gun is still accelerating a mass of some sort, and due to the conservation of momentum some of the force has to be put back on the gun. It's no different than firing a bullet.[/QUOTE] It's not accelerating anything. Light has a constant speed, [i]c[/i] if you remember. It also has no mass, so imparting or receiving any kind of kinetic energy to or from it directly is impossible. A laser, IIRC generates and focuses photons to be parallel in some manner I don't fully understand. [editline]11:01PM[/editline] Also Star Wars lasers aren't plasma either, nobody knows for sure but the best bet at a pseudo-scientific explanation I've heard is this: [url]http://web.archive.org/web/20000817192432/www.synicon.com.au/sw/ls/sabres4.htm[/url]

[QUOTE=duce2231;22145819]Actually, you can see LASERs in space because they are a light wave. Light waves are electromagnetic and can travel through a vacuum. If this wasn't the case for light waves, we wouldn't be able to see the Sun from Earth. Overall, this was a very dumb thing to say. I capitalize LASER, because it is an acronym, and Google Chrome must not respect the use of acronyms because they are saying it is misspelled.[/QUOTE] Do laser beams emit light? No, because they are light themselves.

Now if we take these lasers and add sharks...

Actually this is bullshit in fallout 3 my laser rifle had a beam shooting out so this isn't true :downs: