Army's High-Speed Laser Hits Shell

CNN ^ | 11/09/2002 | Associated Press

[calenel]

Weapons that travel far faster than the proverbial speeding bullet are as little as five years from use in combat, say defense officials who used a laser to shoot an artillery shell out of the sky this week.

[Einigkeit_Recht_Freiheit]

Offense, Defense, Offense, Defense.

That's how it has always worked. I am glad we are concentrating more on the defense at the moment.

[PeoplesRepublicOfWashington]

"High-Speed Laser"? I thought all lasers traveled at the same speed.

[CholeraJoe]

My thoughts exactly. Light speed is light speed.

[JameRetief]

Light speed is light speed.

Oh Yeah? New (at least new to many people) theories are challenging that concept: Light speed is light speed.

[JameRetief]

I thought all lasers traveled at the same speed.

Actually, they don't. A pulse of light can have more than one speed because it is made up of light of different wavelengths. The individual waves travel at their own phase velocity, while the pulse itself travels with the group velocity. In a vacuum all the phase velocities and the group velocity are the same. In a dispersive medium, however, they are different because the refractive index is a function of wavelength, which means that the different wavelengths travel at different speeds.

[JameRetief]

I just realized, I didn't copy and paste the title onto th elink above. It should say: Inconstant Speed of Light May Debunk Einstein.

[calenel]

I think they meant "High-Speed" in terms of its ability to react to and destroy high velocity targets.

[JameRetief]

Yes, in the article, the author was being redundant.

I should have also mentioned the phrase "High Speed" was not discussing the speed of the laser, but the relative speed of the laser technology to other defensive technologies. The information I mentioned in my posts above was not relevant to the article itself, but I thought some people might find it interesting.

[MD_Willington_1976]

Is it called the "Allen Parsons" project..."Mini-me"....ah nevermind...

[PeoplesRepublicOfWashington]

In a dispersive medium...different wavelengths travel at different speeds.

Interesting. So if I have a red laser and a violet laser, and I fire both at sea level, what are their respective speeds? Are they much different than 186,000 mi/s?

[PeoplesRepublicOfWashington]

The team, led by theoretical physicist Paul Davies of Sydney's Macquarie University, say it is possible that the speed of light has slowed over billions of years.

Is that why FR has been responding slowly recently?

[da_toolman]

Interesting. So if I have a red laser and a violet laser, and I fire both at sea level, what are their respective speeds? Are they much different than 186,000 mi/s?

Uneducated guess here, but I'd call 'em "High Speed", leave it at that, and go have a beer, but that's just me.

[PeoplesRepublicOfWashington]

I'd call 'em "High Speed", leave it at that, and go have a beer...

There's a wise philosophy.