Is it possible for Professor Threestone to build a machine like that?
a) It's crystal clear. It's not possible to build a machine like that. One source only creates one shadow behind an object. If two shadows should be created, two sources of light are needed.
b) It's obvious that Professor Threestone is able to build a machine like that. He only needs a very strong source of light because if there is a lot of light, a lot of shadows can be created.
c) It's easy. Professor Threestone can build a machine like that using a prism. The prism divides the light into spectral colours and every colour creates a shadow behind the object.
d) It's easy. Professor Threestone can indeed build a machine like that. He only needs a mirror. The mirror creates a virtual reflexion of the source of light. This itself creates its own shadow.
