Quantum mechanics is undoubtedly the most successful scientific theory of all time. Not only did it explain our world, but it also changed it — through technology — more than anything else in human history so far. At the same time, however, the picture of the physical world that emerged from it is the most bizarre the human mind has ever faced. With the "bone of contention" being the fundamental randomness of the theory; the existence of fundamentally causeless events. The subject of the book is the alternative interpretations to the established quantum mechanics — the Copenhagen quantum mechanics, as it is called — which were proposed as a "remedy" to the "disease" of fundamental probabilism. The uniqueness of the book lies mainly in the author's effort to take a subject notorious for its ambiguity and the variety of its conflicting versions and make it teachable at the basic undergraduate level. A spirit of "insolence" towards dogmatic certainties, combined with a constant readiness for changes and revisions, is the intellectual attitude required by the subject of the book and the book itself. The audience it addresses is restless students and professional scientists who have attended an undergraduate course in quantum mechanics and have a genuine curiosity to see it in the frame of radical questioning.