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No. 169: Vampire Hunters

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Vampire Hunters

First | Previous | 2009-10-23 | Next | Latest

Strip by: Andrew Bird, drachefly

{Scene: Inside a store, with shelves full of items labelled "Garlic", "Holy symbols", "Stakes", "Special". The reversed sign on the outside of the window reads "Vampire Hunters 'R' Us".}
Oliver: Hmm. It says this laser dusts vampires 12 times faster then direct sunlight.
Delkin: How fast is that, anyway?
Oliver: No idea - ever used that method myself...
Oliver: {to Meridien, a small flying sprite} Ma'am, are you a sun sprite?
Meridien: Wind sprite. I don't work here, by the way.
Oliver: No matter. How long does it take for sunlight to dust a vampire?
Meridien: Gee. Five... six seconds, maybe?
Delkin: Oliver, this is a laser. You can't use a random fae's approximation!
SFX: Hmph! {Meridien flies off in a huff}

The author writes:

Script by drachefly; art by Andrew Bird.

The random phase approximation is used in physics whenever you have waves (such as light waves) coming at you randomly. It assumes that there isn't any particular pattern in the relative timing of the wave crests coming from different angles or locations or whatever. It's like supposing that people in a crowd are just milling around. This is a totally valid approximation over a lot of real systems - any deviation is much smaller than any reasonable noise level - and simplifies the mathematics a tremendous amount.

But it is not valid for coherent wave sources such as lasers, because instead of milling around, this beam would be more like a phalanx.