The title is pretty much it.
If I brought light source into a room (a space) (completely) covered in Vantablack. How would that affect the visibility in that room (space). (if it would make any difference at all)
Title Note: Not necessarily a candle, a light of some sort (which would be sufficient enough to fully lighten a conventional room).
Related Questions:
Well the walls of the room wont scatter any light, but everything else will scatter light just as it normally does. It'll be like holding a candle in space.
You would just see the candle and nothing else. The walls would almost completely absorb all incident radiation from the candle, so there'll be no reflection from it, but the EM radiation from the candle would still enter your eyes so you would still see it.
The effect would be almost indistinguishable from lighting said candle in a room painted with normal black paint. The shadows would be rather stark.
The difference would be that there would be no diffuse light coming off of the walls. Normally some tiny fraction ( a few percent) of the light would bounce off of the walls, providing some light on the surfaces that are occluded from your light source. However, this effect is tremendously slight.
To see how this would work, we can look at the opposite. In 3d rendering, one famous construct is the Cornel Box
Note that the light off of the red and green walls causes the boxes to have a slight hue on the sides nearest the walls. This is the diffuse effect that the Cornel box seeks to demonstrate.
Of importance is just how hard the Cornel box had to work to create a structure which demonstrated this effect. Typically the effect is so slight that 3d graphics engines don't even model it. Black walls (even non-vantablack) are especially good at not causing this effect. You could certainly measure it with a photometer, but the human eye would not notice the difference.
