Also a technique used all over the place for studying how molecules react to light. Probe it with as short of a laser pulse you can afford to buy and measure the light emitted by it some time later. My wife has been doing this basic technique for years studying things like molecules to generate fuels from sunlight. (Or was until solar energy funding as practically eliminated last year, now it's studying other things using similar techniques)

Um... "rendering" is in the title, and implies that no one is literally "flying with photons". What part did you believe was "real"?

Please define 'real'.

It's measuring light through multiple samples, and then aggregating them together. Not all that different from a long exposure photograph.

Well, this does the actual measurement. Measurement is how deviations from theory are discovered.