Perceiving the World  
 

source / target / detector:  the way we see the world

light bulb behind you, tennis ball in front of you

• photons travel from light bulb (source)
• bounce off the tennis ball (target)
• hit your eye (detector)
• different photon wavelengths reveal color

from photon's direction, you "see" a round object

(dolphins and bats emit and detect sound waves
       to "see" with acoustic "sonar" in their world)

reflected waves reveal information about surroundings