View Full Version : Lightwave - the real thing in motion (MIT labs)

12-14-2011, 02:30 AM



and pop bottle

bbc story:

have to say newtek have the most accurate name for a 3d rendering app.

12-14-2011, 04:19 AM
I always thought the name LIGHTWAVE 3D to be the best and most aesthetic name of all the 3d programs out there.

12-14-2011, 11:26 AM
have to say newtek have the most accurate name for a 3d rendering app.

Like many people, I was always baffled by the supposed wave-particle duality of photons until I read more deeply into quantum electrodynamics (QED).

Richard Feynman was very clear: photons are particles (packets of energy), end of story.

The "wave" aspect we see is a side effect of the complete probabilistic behavior of the paths these photons travel and the probability of events (called the photon's probability amplitude).

The probability amplitude--the probability of a certain event happening such as the absorption or emission of the photon by an electron--results in a distribution that looks to us at the macroscopic scale to be in the form of a constructive or destructive "wave pattern" that a detector sees (for example, the retina of our eyes). The probability amplitude and the math describing its behavior (the math behind Feynman Diagrams) explains refraction, reflection, lens focusing, why light travels in a straight line (yes, even why light appears to travel in a straight line), why the angle of incidence appears to equal the angle of reflection (it's not strictly true the angle of incidence equals the angle of reflection for all photons, at the macroscopic scales averaged over billions of photons it gives this appearance because light appears to want to take the shortest amount of time between two points), and all other forms of light and matter interaction. Strange stuff.

And most strangely, it all appears to be based on time. A lens focuses light because light wants to take--on average over billions of photons--the least amount of time to travel from one point to the next. That's why a focusing lens needs to be curved, thicker in the middle and thinner at the ends (see [2] below). The bending behavior of the lens is a side-effect of least-time. The same for refraction, the bending of the photon path appears to be based on least-time, but only on average over billions of photons, not every photon.

And all this based on the seemingly random and probabilistic behavior of a particle: the photon.

I still don't understand the all the math behind quantum electrodynamics, and I may never, but I'm trying.

My point is, more accurately it would be called LightProbabilityAmplitude or PhotonProbabilityAmplitude, but LightWave sounds much cooler. ;-)

I started down this path because I could not answer a simple question: "How does light actually reflect off a surface?" The answer was absorption of the incoming photon by an electron within the surface and emission of an outgoing photon by that electron based on a probability amplitude of those events occurring.

Very cool stuff. [1] is a very slow read as it goes deeply into the Path Integral. [2] is technically accurate but skips the math.

[1] Quantum Mechanics and Path Integrals by Richard P. Feynman and Albert R. Hibbs
[2] QED the strange theory of light and matter by Richard P. Feynman

12-14-2011, 01:34 PM
I remember watching a documentary on Feynman in my twenties, turned out he liked to go sketch women in the local topless bar while thinking his ideas through, why is the world not still like this I ask myself ?

12-15-2011, 01:57 PM
Since this is a forum on LightWave and CG and not quantum physics, here's a combination of a CG animation and quantum physics that may help confuse you even more, the infamous double-slit experiment:


The wave function is generally interpreted in terms of probabilities as I described earlier.

The Path Integrals from [1] in my previous post is one form of the mathematics to explain the "all paths simultaneously" you see near the end of the animation and was one of many of Feynman's contributions to the field.

Photon (and electron) behavior is explained mathematically as if they take all possible paths simultaneously as they propagate. Truly strange.

LightWave 11, with help from Bullet, could easily create this animation.