The Wave Function

Part of the UNITEXT for Physics book series (UNITEXTPH)


Among the fundamental constants of Physics, Planck’s constant h is an action [h = energy \(\times \) time= angular momentum]. It is a tiny action, \(h \sim 6,626196 10^{-34}\) J s. Most often, one uses the notation \(\hbar =\frac{h}{2 \pi }=1.054 10^{-34}\) J s. All the phenomena in which h is non-negligible are quantum phenomena, while sometimes phenomena in which the characteristic actions are \(\gg h\) may have classical aspects, which allow for a simpler description; however all the microscopic mechanisms are fundamentally quantum, and many phenomena such as magnetism, superfluidity and superconductivity are just macroscopic quantum phenomena; their quantum mechanical description is far from trivial. Historically, the breakdown of classical Physics (after many triumphs) was urged by the clear inability of the latter to explain a few quantum effects that where known by 1900. This breakdown was shocking, because well-understood laws of Physics that had been validated by experiment in many ways were seen to lead to wrong conclusions in a class of phenomena quite unexpectedly.

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© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Università di Roma Tor VergataRomeItaly

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