The rise of quantum mechanics is reviewed with special attention to the development between June 1925 and October 1927 when the Copenhagen interpretation was proposed.
Of all the many rival interpretations of quantum mechanics, none is more important or influential than the Copenhagen interpretation. Unfortunately, there is no one Copenhagen interpretation of quantum mechanics. If one uses the expression, and everyone does, one should not think of the Copenhagen interpretation as a single consistent interpretation of the theory. Philosophers of physics tend to use the expression ‘the Copenhagen interpretation of quantum mechanics’ as a label covering a variety of different interpretations all of which either originate with Niels Bohr or were invented by him, his colleagues and guests at the Institute for Theoretical Physics in Copenhagen beginning in the middle 1920s. Perhaps one should say that the Copenhagen interpretation in this diffuse sense goes back farther than this, back even before the rise of the new quantum mechanics. Heisenberg tells the story of a boat trip he, Bohr, and some friends took from Copenhagen to the island of Fyn around the time when the then new quantum mechanics was being developed. Bohr, ‘full of the new interpretation of quantum theory’, talked of ‘the difficulties of language, of the limitations of all our means of expressing ourselves’ and of how these limitations had been expressed ‘in the foundation of atomic theory in a mathematically lucid way’. ‘Finally,’ Heisenberg ends the story, ‘one of the friends remarked drily, “But, Niels, this is not really new, you said exactly the same ten years ago”
Quantum mechanics has become the rising trend in modern physics and has completely changed people’s views of physics. This essay delves into the once-existing problems underlying quantum mechanics such as the conflict between substantiality and completeness in quantum mechanics and the relationship between causality and observation and analyzes the solutions to the controversies. The Copenhagen Interpretation is widely considered the most orthodox explanation of quantum mechanics; therefore, this paper focuses on the Copenhagen Interpretation and examines how it delicately manages to explain quantum mechanics. It also examines its alternative theories, such as Einstein’s local hidden variable theory, and disproves them with Bell’s inequality and other reasonings. The essay aims to clarify and systematize the historical development of quantum mechanics, showing the current progress of quantum mechanics.