The Mach effect can refer to: Mach bands are an optical illusion that are often referred as "the Mach effect". Mach's principle – a hypothesis attempting to explain a frame of reference for rotation Mach effect or Mach effects (for spacecraft propulsion) – see Woodward effect Mach-effect thruster – a hypothetical reactionless drive
See also Sonic boom, an effect of traveling at Mach speeds in fluids