Hallo, i am trying to make the simulation based on the Feynman QED (as you can see on the pictures below) in EJS, but to say the true, i dont even know how to start. My goal is : Two mirrrors, which can be changer (straight and concave), the user will click on any place in the mirrors and in the second window he will see the summation of probability amplitudes. Can anybody help me, please ?