Re: Laser snipers

Chris

>SG says snipers sometimes carry laser weapons.  However, I recall a
>discussion in which it was said the x-ray lasers so beloved of my
Traveller
>characters would hardly be silent/invisible--more like a lightning
bolt.
>Don't know whether that was accurate, though.
>
>So, questions for you educated blokes:

I'm doing my degree if that counts!

>a. would/could a military laser weapon be invisible/inaudible?  Or
would it
>be useless to snipers due to signature?  (assumes a standard Earth
>atmosphere with no unusual components)

Um, the noise would be a question of the gun itself, rather than the
passage 
of the laser beam, the lightning bolt effect could possibly be to do
with 
the beam being cut off, and the vacuum (and particularly the lack of
heat) 
creatde by it, causing thunder in the same way as lightning causes it,
BUT 
this could be easily avoided by using either pulse lasers (which can
deliver 
more energy anyway) or by fading the beam away rather than cutting it
off.

>b. in a zero gee environment, would lasers have *no* recoil?  This
doesn't
>seem logical because we've talked about a lasers as a ship drive, so
there
>has to be some recoil....but how much?  Either as compared to a rifle,
or 
>in
>SI units.

Photon's are very tiny particles that behave like waves, (or the other
way 
round, its complicated). Some A-level quantum physics:

The de Broglie wavelenght is expressed as planks constant/its momentum
(aha 
I here you cry if it has momentum then it must have mass, resulting in 
recoil...) But: Plank's constant is REALLY Small 
(0.00000000000000000000000000000000002, or around that) and so the
momentum 
is Really small too, since the velocity is pretty big (the speed of
light) 
this means that the mass must be very very 
small:(0.000000000000000000000000000000000000000000000000000000000000000
01 
Kg) so yes there is SOME recoil, but barely noticable (like the recoil
when 
you speak), so I'm not sure how you would use light as a drive for a
space 
ship.

Hope that helps

Richard

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