: In June 1925, Werner Heisenberg was staying on the island of - TopicsExpress

: In June 1925, Werner Heisenberg was staying on the island of Helgoland, recovering from a severe attack of hay-fever. Here he found and invented quantum mechanics as we now still know it. Back home after his stay he wrote a paper of which you can find a copy here (gimbl/lat/docs/Heisenberg_1925.pdf). The paper was recognised rapidly as a breakthrough, although even now it is difficult to read and understand, even by experts. How Heisenberg came to the calculations which he presents in the paper, and that finally showed to be the calculations that we still make nowadays in this very robust theory that quantum mechanics is, remains mysterious. Nobel Laureate Steven Weinberg commented in the following amusing way on this difficult aspect of the original paper containing the birth of quantum mechanics : If the reader is mystified at what Heisenberg was doing, he or she is not alone. I have tried several times to read the paper that Heisenberg wrote on returning from Helgoland, and, although I think I understand quantum mechanics, I have never understood Heisenberg’s motivations for the mathematical steps in his paper. Theoretical physicists in their most successful work tend to play one of two roles: they are either sages or magicians ... It is usually not difficult to understand the papers of sage physicists, but the papers of magician-physicists are often incomprehensible. In this sense, Heisenberg’s 1925 paper was pure magic.