The cerium impregnated handpads utilize a material manufactured by 3M that contains an encapsulated cerium in tiny pyramid shapes on the surface of the pad. When the material comes in contact with water, cerium is released slowly from the pyramid shapes.
The pressure that you apply with the pad to the surface of the glass utilizes the same tiny pyramid shapes to generate the friction required for the cerium to polish the glass. It will still require a lot of patience, pressure and back and forth movement, but the hand pads will polish your glass quite efficiently and allows for polishing without mechanical help, something that was never possible before.
(Just in case your wondering, the cerium is the white slick looking side of the hand pad).