Decoherence and the appearance of classicality in physical phenomena
It is accepted that among the ways through which a quantum phenomenon decoheres and becomes a classical one is what is termed in the literature the Zeno effect. This effect, named after the ancient Greek philosopher Zeno of Elea (born about 485 B.C), were used in 1977 to analytically predict that an initial quantum state may be preserved in time by merely repeating a large number of times, in a finite total time, the experiment of checking its state. Since then this effect has been experimentally validated and has become an established physical fact. It has been argued by Simonius that the Zeno effect must be related not only to quantum phenomena but also to many macroscopic and classical effects. Thus, since it operates in both quantum and classical regimes it must cause to a more generalized kind of decoherence than the restricted one that ``classicalizes'' a quantum phenomenon. We show that this generalized decoherence, {\it obtained as a result of dense measurement}, not only gives rise to new phenomena that are demonstrated through new responses of the densely interacted-upon system but also may physically {\it establish} them. For that matter we have found and established the analogous {\it space Zeno effect} which leads to the necessity of an ensemble of related observers (systems) for the remarked physical validation of new phenomena. As will be shown in Chapters 3-5 of this work the new phenomena (new responses of the system) that result from the space Zeno effect may be of an unexpected nature. We use quantum field theory in addition to the more conventional methods of analysis and also corroborate our analytical findings by numerical simulations.