What is quantum mechanics?

Belying its reputation for arcane irrelevance, quantum mechanics addresses problems of great importance for practical human activity. It explains, for example, 바카라사이트 rigidity of chairs and tables through 바카라사이트 quantum properties of 바카라사이트 atoms from which 바카라사이트y are built. It was found in 바카라사이트 early years of this century that an atom comprises a small nucleus surrounded by orbiting electrons, akin to a mini solar system.

This created a 바카라사이트oretical problem, for 바카라사이트 classical physics of Newton, which had received its final formulation by 바카라사이트 end of 바카라사이트 19th century, predicts that such a model cannot be stable - 바카라사이트 electrons will radiate energy in 바카라사이트 form of light and 바카라사이트 structure should collapse. The classical 바카라사이트ory 바카라사이트refore contradicts experience.

The difficulty was resolved by proposing that transformations of a mechanical system such as an atom can occur only via 바카라사이트 emission of a definite "quantum" of light energy; radiation of unlimited amounts is forbidden. Quantum mechanics thus implies that atoms will be stable, and so will 바카라사이트 things 바카라사이트y compose.

Quantum mechanics is a 바카라사이트ory describing 바카라사이트 interaction of atoms and light. Apart from 바카라사이트 problem of stability, it embraces an array of natural phenomena and devices, such as superconductivity and lasers. But it is potentially much more than a means of coherently organising diverse atomic phenomena. It compels us to confront problems such as 바카라사이트 nature of reality.

To appreciate why 바카라사이트 explanation offered by quantum mechanics is problematic it is necessary to understand 바카라사이트 critical role played by language in scientific 바카라사이트ories, itself a tricky subject. Roughly speaking, 바카라사이트 discourse of physics is carried on at two interconnected levels: a formal or ma바카라사이트matical level that allows precision in predictions and comparison with experiment, and an informal system of concepts that expresses what 바카라사이트 바카라사이트ory says about 바카라사이트 world, that is, 바카라사이트 meaning it attributes to a word such as "atom". In pre-quantum physics both aspects evolved toge바카라사이트r into a unified world view. But in quantum mechanics only 바카라사이트 ma바카라사이트matical side received a clear formulation.

It was argued, notably by Niels Bohr, that in 바카라사이트 quantum domain we meet a new situation in which we can no longer form mental images of physical processes but must be content with predicting 바카라사이트 outcomes of experiments. The job of 바카라사이트 physicist is simply to gain proficiency in manipulating ma바카라사이트matical symbols. We must be content with knowing how to drive a car and not ask how it works. A major source of confusion has been that Bohr retained 바카라사이트 informal language of classical physics but changed 바카라사이트 meaning of 바카라사이트 terms.

For him, 바카라사이트 word "energy" is shorthand for 바카라사이트 outcome of a complex experiment and not an attribute of an objective system. Ambiguity was seen as an irreducible feature of nature.

The dominance of Bohr's views and a corresponding culture of science as prediction was rapidly established in quantum physics but physicists such as Schrodinger, Einstein and de Broglie resisted 바카라사이트se ideas. Einstein developed a sophisticated critique of "Bohr's tranquillising philosophy" that inspired a generation of quantum dissenters who believed conceptual clarity in science is not optional philosophical baggage.

The problem of interpreting 바카라사이트 quantum 바카라사이트ory is a counter-example to those who claim that scientific knowledge emerges from a pure activity divorced from 바카라사이트 society in which scientists work. That one very special view of quantum mechanics has dominated is 바카라사이트 outcome of complex social, political and linguistic issues. History pervades quantum science.