Philosophy of quantum mechanics

Quantum mechanics has provided much controversy in philosophical interpretations. As it developed its theories began to contradict many of the accepted philosophies. However, all its mathematical predictions coincide with observations.
In most cases accepted philosophies are based on the everyday experience of the average human - which is extremely limited as it does not include observation of ultra-small systems, or motion with high speeds, or experimenting with high energies, strong gravity, etc. Thus, common-sense "theories", "intuitions" or "feelings" cannot be relied upon when it comes to descriptions or explanations of the behavior of many systems and objects in nature.
[edit] Determinism
The 18th century saw many advances in the domain of science. After Newton, most scientists agreed on the presupposition that the universe is governed by strict (natural) laws that can be discovered and formalized by means of scientific observation and experiment. This position is known as determinism. However, determinism precludes the possibility of free will. That is, if the universe, and thus the entire world, is governed by strict and universal laws, then that means that human beings are also governed by natural law in their own actions. In other words, it means that there is no such thing as human freedom (except as defined in compatibilism). Conversely, if we accept that human beings do have (libertarian or incompatibilist) free will, then we must accept that the world is not entirely governed by natural law. Some have argued that if the world is not entirely governed by natural law, then the task of science is rendered impossible. However, the development of quantum mechanics gave thinkers alternatives to these strictly bound possibilities, proposing a model for a universe that follows general rules but never had a predetermined future.
[edit] Uncertainty principle
Main article: Uncertainty principle
The Uncertainty Principle is a mathematical principle that follows from the quantum mechanical definition of the operators of momentum and position (namely, the lack of commutativity between them) and that explains the behavior of the universe at atomic and subatomic scales.
The Uncertainty Principle was developed as an answer to the question: How does one measure the location of an electron around a nucleus if an electron is a wave? When quantum mechanics was developed, it was seen to be a relation between the classical and quantum descriptions of a system using wave mechanics.
In March 1926, working in Niels Bohr's institute, Werner Heisenberg formulated the principle of uncertainty thereby laying the foundation of what became known as the Copenhagen interpretation of quantum mechanics. Heisenberg had been studying the papers of Paul Dirac and Jordan. He discovered a problem with measurement of basic variables in the equations. His analysis showed that uncertainties, or imprecisions, always turned up if one tried to measure the position and the momentum of a particle at the same time. Heisenberg concluded that these uncertainties or imprecisions in the measurements were not the fault of the experimenter, but fundamental in nature and are inherent mathematical properties of operators in quantum mechanics arising from definitions of these operators.[2]
The term Copenhagen interpretation of quantum mechanics was often used interchangeably with and as a synonym for Heisenberg's Uncertainty Principle by detractors (such as Einstein and the physicist Alfred Lande) who believed in determinism and saw the common features of the Bohr-Heisenberg theories as a threat. Within the Copenhagen interpretation of quantum mechanics the uncertainty principle was taken to mean that on an elementary level, the physical universe does not exist in a deterministic form, but rather as a collection of probabilities, or possible outcomes.[citation needed] For example, the pattern (probability distribution) produced by millions of photons passing through a diffraction slit can be calculated using quantum mechanics, but the exact path of each photon cannot be predicted by any known method.[citation needed] The Copenhagen interpretation holds that it cannot be predicted by any method, not even with theoretically infinitely precise measurements.
[edit] Complementarity
The idea of complementarity is critical in quantum mechanics. It says that light can behave both like a particle and like a wave. When the double slit experiment was performed, light acted in some cases as a wave, and some cases as a particle. Physicists had no convincing theory to explain this until Bohr and complementarity came along. Quantum mechanics allows things that are completely opposite intuitively to each other to exist without problem.