Stealthy Weapons (Lasers, Gauss, etc)

Reminds me of the aforementioned Traveler campaign. Xray lasers were supposed
to be silent and invisible. The engineer of the group calculated that you'd
see the line of superheated air between laser and target, and hear the
thunderclap, so it would be a lot stealthier to take an M16..

** Similarly, I imagine a gauss projectile would probably heat some air. The
question you have to ask is (in either case):

Is there enough heat discharged into the air to make the air glow? For how
long? To what extent? How inefficient would that make the weapon if its
expending profligate energy into the air like this?

I'm not sure I buy the argument about a visible track on a laser. I've seen
high intensity lasers at work and didn't see that effect. However, the crack
or crackle was noticeable. Probably not as loud as a rifle discharge, but not
silent either. Any object tunnelling through air rapidly thus having a vaccum
to fill behind it or any beam displacing air energetically and thus
leaving a vacuum tunnel will have some sort of sound - a crack, a
crackle, a
thunderclap - depends on the size of the tunnel through the air I'd
think.

Laser might be a good sniper weapon for accuracy, and its awesome in space
(great marine weapon) and on small asteroids and airless moons. Gauss weapons
are probably just as good in atmosphere and not subject to problems shooting
through mist or aerosol obstructions...

T.