MOMENTUM IS NOT TO BE CONFUSED WITH KINETIC ENERGY, THEY ARE DIFFERENT PHENOMENA
KINETIC ENERGY IS NOT TO BE CONFUSED WITH MOMENTUM, THEY ARE DIFFERENT PHENOMENA.
IF YOU DO NOT KNOW THE DIFFERENCE, PLEASE LEARN WHAT IT IS BEFORE COMMENTING ON PHENOMENOLOGY OF HYPOTHETICAL SCIENCE FICTIONAL DEATH RAYS.
Fantasy death rays without even the thinnest pretense of basis in science are another matter, though; knock yourself out.
CaptainDeez, on 09 May 2012 - 09:39 PM, said:
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Lasers aren't quite the same as a particle beam. Lasers are focusing light which means photons. They emit EM radiation, which will heat and vaporize material to cause damage.
A particle beam is acutal matter(like ionized hydrogen) that's sent hurtling at a target by a particle accelerator. Those particles aren't vaporizing material on a target, they are battering it apart with kinetic energy. A particle beam has more in common with a rail gun than a laser.
Technically a PPC should be able to run out of ammo.
I am really trying to make this as clear and easily understood as possible, because it is a cryin' shame that so many people don't understand this, so I try again...
Momentum = Mass * Velocity
Kinetic Energy = Mass * Velocity * Velocity
As you can see, the difference between these two values is literally a factor of velocity. The speed of light is a very high value, so if you throw your projectiles at very near the speed of light, you will get very, very little momentum relative to the kinetic energy that you are projecting. Looking at it from the other side, you need tremendous energy per unit mass in order to get that velocity, to the extent that the mass of "ammo" a PPC would need is utterly negligible even when scaled up to orbital bombardment scale. Does this relationship make sense?
If it still doesn't make sense, consider that the speed of light is a kinda high value, so if we call that C, then the relationship between (MC) and (MCC) is kinda dramatic.
Light itself is just the case where the mass value is minimal (theoretical rest mass at zero, for what little that matters) and velocity maximal, it does not follow vastly different physical rules or anything. When a photon is absorbed by any baryonic matter, the light imparts a kinetic impulse. Laser death rays and PPC could easily have distinguishable effects, but they would have a lot more in common with each other than anything and every thing that shoots stuff at very much less than the speed of light.
Strictly speaking, light heats things by being converted into kinetic energy. As such, light does deliver kinetic energy, even if we take the purely semantic position that light is not a pure manifestation of kinetic energy mostly unencumbered by momentum. The more light-like the projectile velocity, the more light-like the behaviour of the "gun."
There is just no weaseling around this; if you say your death ray throws stuff at very near the speed of light, then you are also saying it delivers stupendous kinetic energy per unit recoil- or, if you prefer, that the recoil is tiny relative to the kinetic energy projected. If the velocity were low enough that it could look more like a gun than a laser, it would be called a plasma cannon rather than a particle cannon, because the definitive difference between the two is whether the particles have time to interact with each other enough to recognise plasma dynamics, which is defined by whether they are moving at fantastic or mundane velocity. Maybe this is why Battletech has a canonical Plasma Cannon which looks kinda like a PPC but differs in that it projects enough particles to require tracking ammo. That does not mean a death ray shouldn't hit harder in practical terms; if you dump enough energy into something to violently explode a hunk off of it simply by heating it fast enough, that exploding mass should deliver some momentum.
On collision with any baryonic matter, the kinetic energy of a particle stream anywhere remotely near the speed of light would be mostly converted to heat. For a death ray, the effect would be very similar to that of a comparatively powerful laser, except that the baryons or electrons (whichever your PPC uses) might much better penetrate the plasma cloud formed at the impact site than most practical wavelengths of light would. (Some of the highest-frequency light will go through the plasma AND through non-plasma air, but is hard to focus. You win some, you lose some.)
The heavier particles will have more momentum than light of similar energy, enough that they will deposit their energy very usefully deeper into the target, but it's still a small value in terms of recoil and initial impact; depending on wattage, it will have an effect on-target more or less resembling a laser heat ray, laser blaster, or "ray beam." (delightfully-named laser death ray which emits 2 to 200 nanometre light so it can more easily bore deep into the target, the tradeoff being that it needs to bore through air as well since air is not transparent to those wavelengths) See
http://panoptesv.com...ay/RayBeam.html for more detail on "ray beams," since I am not sure if the term has caught on in the mainstream...
Do you know why hard science fiction rarely bothers with "animatter beams?" Well, neither do I, but my guess is that the kinetic energy:mass ratio at "nearly the speed of light" is so stupendously high that direct conversion of the beam's mass to energy would not add much to the effect for what it would cost to screw around with antimatter; it definitely looks more laser-like than bullet-like, if you ask me.
Formatting work when tags are used in the input field is getting to be a pain, is there any plan to fix the parsing rules so they are consistent and easy to use?
Edited by Owl Cutter, 10 May 2012 - 12:40 PM.
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