1. A method of obtaining an indication about the existence of a feasible solution for a bounded instance of a problem that belongs to the non-deterministic polynomial class of problems, using parallel optical computations employing a multitude of light rays simultaneously propagating along paths in an optical arrangement, said method comprising: determining an optical arrangement being capable of implementing a universal non deterministic Turing Machine that can solve bounded instances of problems of said class; directing at least an initial incoming ray to a point in said optical arrangement that represents the initial configuration of said universal non deterministic Turing Machine, said initial configuration corresponds to said bounded instance; splitting each incoming ray within said optical arrangement into at least two outgoing rays at pre-determined locations in said optical arrangement; amplifying each incoming ray and/or outgoing rays, such that each of said outgoing rays has at least the same power as said initial incoming ray; using the position, measured in two or more dimensions, of said rays, on the components of said optical arrangement, to represent intermediate and/or final computation results; and whenever an outgoing ray is detected, within a predetermined time, at a position in said optical arrangement that represents a final state of said universal non deterministic Turing Machine, converting said position to said indication.