As one of the greatest advances of the twentieth century in science, quantum mechanics explains the behavior of matter and energy. It states that the elementary particles can behave as particles in a given time and waves in the next or the previous.

The book explains the following two pillars of this theory: Particles exchange energy at integer multiples of a minimum possible, denominating, quantum (quantum) of energy; The position of the particles are defined by a function that describes the probability that the particle is in that position at that moment.