many many reasons why optics is so powerful but we face challenges one of the challenges is called diffraction right in high school or middle school we were taught that you can focus a light beam through a lens to a geometric point all right if you say that in a high school you get a full mark right but if you say that in college the professor may tell you you're wrong right so because light is a wave anyways cannot be focused to a point a geometric point right the ultimate size of the focal point depends on the