In fact each object reflects a part of the light on the nearest  objects. This effect is usually more or less rendered  in the using of an ambient light.

However, this ambient light  is far from being satisfactory, because it doesn't take the colour into account. You can notice on the picture here aside the importance of the red and green reflects from the walls onto the objects in the centre. To obtain this result there is a global computation method for the illumination of the scene that we call : radiosity. This is a great speciality of the Cornell university which experimental model, the famous cornell's box is now the reference in the domain.

However radiosity is a hard stuff to use either by means or by the  time of computation it needs.