InfernalDarkness: *"you seem to think that real light acts in some mystical and unforeseeable way, my friend. that it's not caculable by mathematics, and that photons don't follow physical rules which are in fact computable. this mystical world of light seems very poetic, but doesn't reflect the reality of things at all."*

I may seem to think that to you, but I suspect that you are very alone in the perception.

"PJF certainly did imply such things, Rayraz. more than that, he outright stated that real light can't be simulated on a computer. scroll up."

You've moved on from what might be excused as a subjective perception and onto something that is demonstrably untrue ("scroll up").

"PJF, I meant that REAL radiosity is indeed just like real light, because it actually is real light."

Radiosity is a computational algorithm, and that is the limit of its reality. The term "radiosity" has no meaning outside of this area, despite careless use by computer graphics aficionados. There is no real light in computer graphics, and radiosity algorithms do not operate in a way analogous to real light. They simply make use of some of the characteristics of real light in their mechanism.

"radiosity simluations only work backwards in Bryce."

(There are no radiosity simulations in Bryce.) Radiosity algorithms involve having their "patches" (subdivided surfaces) look into the rest of the scene to examine the brightness of the other patches. Even those patches that are assigned to be initial "emitters" are actually just given an arbitrary brightness level for the other patches to look at. Having patches look out to see the brightness of other patches is "backwards" compared to the movement of real light.

I can't be bothered tonight to argue with you about photon mapping. So for now I'll just quote the specifications for your beloved Mental Ray:
http://www.mentalimages.com/2_1_1_technical/index.html
"photon mapping combines forward and backward ray tracing and simulates all possible light paths, without the need to prepare and combine each effect separately"

"using Final Gather produces emission of light from any surface, based on a huge quantity of possible attributes."

Final Gather uses "data rays" sent from the camera to 'bounce' off of initial pixels and pick up information from secondary pixels. It's a backwards firing, ray-traced process that has no similarity to real light.

"to understand the nature of debate is to understand that i am what I say, and am without equal in this arena.

Definitely without equal.