Raytracing "sees" the pixel on the other side of the screen; but doesn't this mean the rays traced can be computationally reflected and refracted imitating the properties of actual light?

It'd be exciting if it were possible. Any visual scene possible outside computer graphics will be possible just using physics equations.

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    $\begingroup$ Raytracers which render reflections and refractions have been ubiquitous for many many years. $\endgroup$ – Rotem Oct 6 '15 at 13:59
  • $\begingroup$ Path tracing does just that: bounces rays around the scene using the properties of the surfaces it hits to determine bounces. thepolygoners.com/tutorials/GIIntro/GIIntro.htm iquilezles.org/www/articles/simplepathtracing/… $\endgroup$ – RichieSams Oct 6 '15 at 14:39
  • $\begingroup$ Youd likely be interested in reading about how the used raytracing techniques to render the black hole in the movie interstellar. They used realistic physics equations and the result was so interesting that they were able to publish a scientific research paper with the results. wired.com/2014/10/astrophysics-interstellar-black-hole $\endgroup$ – Alan Wolfe Oct 8 '15 at 14:26
  • $\begingroup$ Because we currently render movies using . . . magic? $\endgroup$ – imallett Oct 18 '15 at 6:21
  • $\begingroup$ Here's a good introduction to monte carlo path tracing, which does what you describe - it uses monte carlo integration to try and solve the rendering equation. It makes for very nice results, but takes a long time to render with the naive implementation. It's still a very active are of research. blog.demofox.org/2016/09/21/… $\endgroup$ – Alan Wolfe Oct 10 '16 at 15:53

You are late by about 35 years. This was addressed in the historical paper "Whitted, T., An improved illumination model for shaded display. Communications of the ACM, Volume 23 Issue 6, June 1980, Pages 343-349", using ray tracing.

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Since then radiosity has been introduced to better deal with diffuse phenomena. Correct physical modeling of the image formation process was discussed six years later in the seminal "Kajiya, James T. (1986), "The rendering equation", Siggraph 1986: 143".

  • $\begingroup$ This is the correct beginning for an answer to this question. But it lacks continuation, you should talk of modern unbiased rendering as well to conclude about the recent convergence of techniques toward Kajiya's equation. $\endgroup$ – v.oddou Oct 7 '15 at 1:23
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    $\begingroup$ @v.oddou: feel free to enter your own. My point is about early techniques to show that this is a pretty old idea. $\endgroup$ – Yves Daoust Oct 7 '15 at 6:10
  • $\begingroup$ If you don't count ray casting (which you shouldn't), this was the first ray tracing paper. So reflections/refractions/shadows have all been here since literally the very beginning. $\endgroup$ – imallett Oct 18 '15 at 6:20

Raytracing is one of the techniques that trace the light as it moves through the scene. This can, depending on the implementation, also include effects such as refraction, reflection and scattering.

Raytracing and similar techniques (see Monte-Carlo Pathtracing for example) all are based on the idea to solve the so called rendering equation. The equation is a long known equation that describes the physically correct amount of light we can see for at each point (this means mathematical infinitesimal point, not pixel!). By (approximally) solving this equation the mentioned rendering techniques are indeed able to render "all" scenes. The only real limiting factors are that it is hard to solve the equation for some effects and the huge amount of computation you need to solve it.

  • $\begingroup$ i wouldnt say we can render all effects. We can render most effects we know of. But rarely do we have the time to program in all effects. $\endgroup$ – joojaa Oct 7 '15 at 16:34

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