Re: What happens to light?

There are a couple of things you need to keep in mind here. 

First, light doesn't really "bounce around". Unless a surface is perfectly 
reflective (an impossibly ideal state), a photon of light is usually 
absorbed by an atom in the surface it strikes. That photon's energy may be 
re-emitted by the atom as visible light, or as heat or other forms of 
invisible radiation, or the energy may go into forming or breaking chemical 
bonds (which is how photographic film, for instance, works). Even the best 
mirror we can make reflects far less than 100 percent of the light which 
strikes it. Think about the multiple images you see when you stand between 
two mirrors, and how many reflections you can see before the images dim to 
extinction. A perfect pair of mirrors would reflect to infinity; regular 
mirrors reflect a few tens of images before the ones in the "distance" are 
no longer visible.

Second, the life of an individual photon is extremely short. The time it 
takes for a photon to travel from the light source to the first object it 
strikes is in the order of picoseconds. The only reason we continue to be 
able to see objects in a room is because the light source emits countless 
numbers of photons every second, which allows the process of absorption and 
re-emission to go on as what appears to be a continuous process. However, 
as soon as the source of photons shuts off, the process stops immediately.