A consumption externality is a situation where a consumer cares directly about another agent’s consumption or production of a particular good. An externality can be positive or negative: 1. Negative: Loud mobile phone use in public places. 2. Positive: Pipe smoking in enclosed public places
All around us: wheels, skaters, ballet, gymnasts, helicopter, rotors, mobile engines, CD disks, … Atomic world: electrons— “spin”, “orbit”. Universe: planets spin and orbiting the sun, galaxies spin, …