# Representing light waves

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I am a computer programmer attempting to represent light rays travelling through the air, bumping into things, reflecting and refracting in some manner as they go through glass or other material.

I have had good luck and the pictures look quite nice representing light photons as long skinny lines whose length is 1/2 the wavelength (ie Red 650 nanometer light is represented as a red line 325 nanometers long, but very, very skinny). They look like light rays that are commonly drawn in pictures. I can turn on a light and have them shoot all over the place.

Regarding the issue of representing the photon as either a wave or a point as it travels though space. My question: Is there a reason that photons are not represented as long skinny rays or arrows with a start and end point that travel at the speed of light?

Thank You

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I'm not sure if i understand your question. When you say 'represent' and 'pictures', are you referring to the way things are drawn in diagrams in textbooks or in some form of computer model.

I would think that if you are modeling the classical properties of light (reflecting, refracting e.t.c.), you do not need to consider the particulate nature of light in your model. Photons may be represented as a little dot if you choose to but you still have to draw vectors showing which way they are travelling. A more common way of representing the photon is the wave-packet.

http://www.cartage.org.lb/en/themes/sciences/Physics/QuantumPhysics/ParticlePhysics/pack.gif [Broken]

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Andy Resnick
I am a computer programmer attempting to represent light rays travelling through the air, bumping into things, reflecting and refracting in some manner as they go through glass or other material.

I have had good luck and the pictures look quite nice representing light photons as long skinny lines whose length is 1/2 the wavelength (ie Red 650 nanometer light is represented as a red line 325 nanometers long, but very, very skinny). They look like light rays that are commonly drawn in pictures. I can turn on a light and have them shoot all over the place.

Regarding the issue of representing the photon as either a wave or a point as it travels though space. My question: Is there a reason that photons are not represented as long skinny rays or arrows with a start and end point that travel at the speed of light?

Thank You
Ray optics, which is essentially what you are re-inventing, is another type of approximation for optical systems. Ray optics assumes that rays begin and end (and can be focused to) infinitesimal points. That is, diffraction is neglected. Typically, the trade-off comes by representing the angle that the ray makes with the optical axis as a sum (approximation to the sine function)- thus, there is first-order ray optics, (sin x ~x), third order, fifth, etc.

Gold Member
I'm not sure if i understand your question. When you say 'represent' and 'pictures', are you referring to the way things are drawn in diagrams in textbooks or in some form of computer model.

I would think that if you are modeling the classical properties of light (reflecting, refracting e.t.c.), you do not need to consider the particulate nature of light in your model. Photons may be represented as a little dot if you choose to but you still have to draw vectors showing which way they are travelling. A more common way of representing the photon is the wave-packet.

http://www.cartage.org.lb/en/themes/sciences/Physics/QuantumPhysics/ParticlePhysics/pack.gif [Broken]
Diagrams and models. The better the objects reflect the underlying physics, the more useful and understandable they are, especially in a simulation where they move around and you have to keep track of things over time. Gravity simulations are easy to do and they "look and feel" real since they follow the laws of physics.

Thank you for the sample.

Ray optics, which is essentially what you are re-inventing, is another type of approximation for optical systems. Ray optics assumes that rays begin and end (and can be focused to) infinitesimal points. That is, diffraction is neglected. Typically, the trade-off comes by representing the angle that the ray makes with the optical axis as a sum (approximation to the sine function)- thus, there is first-order ray optics, (sin x ~x), third order, fifth, etc.

Also, thanks for the hint on ray optics and diffraction. Do you know of any good reference material on the subject?

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Andy Resnick