Mach s picture of a bullet The article now says The first to discover this shock was Ernst Mach in his original picture showing a bullet in a supersonic flow that cause the oblique shock Is this talking about this picture I think this is a picture of a bullet fired into stationary air while the sentence above seems to say that it s being fired into air that was already moving at supersonic speeds I suggest discussing this at Talk shock wave Mach s picture of a bullet since there is already discussion there although I suspect a change in wording in this article is required