Einstein said that the speed of light will be constant irrespective of the speed of its source.. So, suppose your are onboard a supersonic car (imagine!) with the speed of 8 Mach, and you throw a ball in the same direction with a speed of say 1500m/s, the ball will actually have the velocity of 1500 M/s + 8 Mach.. Now instead of the ball, take a torch & switch it on..Einstein says that Light wud still travel at c m/s and not c + 8 Mach m/s... Can anyone justify this? Is there any proof of this?? Thanx!