Would anybody here happen to know whether ray tracing uses fixed-point or floating-point math? This is speculative to the point of stupidity, but if real-time ray tracing is realized in the coming decade would it be offloaded to a CPU, and could that be the death knell for GPUs? Will graphics computation then fall upon Intel's and AMD's ALUs?

for raytracing you need Floating point. Your not going to see realtime raytracing on a CPU for a while yet. (at least not above really low quality)

This may be a stupid question, but why would anyone have to offload the ray-tracing calculations to a cpu(unless you mean separate core). I may be wrong, but I thought gpu's could do floating point calculations as well. GPU's are optimized for 3d rendering anyway, it's only a matter of time until they are powerful enough to do real time ray-tracing.