bow wake
Sonic booms are one example of a broader phenomenon called bow wakes. A bow wake, such as the one in Figure 17.19, is created when the wave source moves faster than the wave propagation speed. Water waves spread out in circles from the point where created, and the bow wake is the familiar V-shaped wake trailing the source. A more exotic bow wake is created when a subatomic particle travels through a medium faster than the speed of light travels in that medium. In a vacuum, the maximum 8 speed of light will be c = 3.0010 m/s ; in the medium of water, the speed of light is closer to 0.75c . If the particle creates light in its passage, that light spreads on a cone with an angle indicative of the speed of the particle, as illustrated in Figure 17.20. Such a bow wake is called Cerenkov radiation and is commonly observed in particle physics.