The apparent reflection of cold if a cold object is placed in one focus surprised Pictet and two scholars writing about the experiment in 1985 noted "most physicists, on seeing it demonstrated for the first time, find it surprising and even puzzling." The confusion may be resolved by understanding that all objects in the system—including the thermometer—are constantly radiating heat. Pictet described this as "the thermometer acts the same part relatively to the snow as the bullet [heat source] in relation to the thermometer." Addition of a very cold object adds an effective heat sink versus a room temperature object which would not, in the net, cool or warm a thermometer in the other focus.