## lördag 13 juni 2015

### The Copenhagen Interpretation of Quantum Mechanics??

If you ask a physicist today about the foundations of modern physics (the theory of relativity and quantum mechanics), you will get most likely get the answer that all basic questions were answered long ago and neither questions nor answers need to be repeated. In short, "science is settled", and the question now is simply how to advance physics further into the unknowns of dark matter, dark energy, string theory and multiversa.

In particular, the answer for quantum mechanics is the Copenhagen Interpretation coined by Heisenberg in the 1950s as an expression of the influence of the Danish physicist Niels Bohr during the formative years of modern physics following the introduction by Max Planck in 1900 of the smallest quantum of action $h$.

One of the few who still worries about the foundations of quantum mechanics is Lubos Motl, who in a sequence of posts on The Reference Frame states his commitment to the Copenhagen Interpretation based on the following postulates:
1. A system is completely described by a wave function ψ, representing an observer's subjective knowledge of the system. (Heisenberg)
2. The description of nature is essentially probabilistic, with the probability of an event related to the square of the amplitude of the wave function related to it. (The Born rule, after Max Born)
3. It is not possible to know the value of all the properties of the system at the same time; those properties that are not known with precision must be described by probabilities. (Heisenberg's uncertainty principle)
4. Matter exhibits a wave–particle duality. An experiment can show the particle-like properties of matter, or the wave-like properties; in some experiments both of these complementary viewpoints must be invoked to explain the results, according to the complementarity principle of Niels Bohr.
5. Measuring devices are essentially classical devices, and measure only classical properties such as position and momentum.
6. The quantum mechanical description of large systems will closely approximate the classical description. (The correspondence principle of Bohr and Heisenberg)
Let us now analyze these postulates from scientific point of view. We find:
1. The idea that the wave function represents the subjective knowledge of a system, makes quantum mechanics into a personal experience, which cannot be science.
2. The idea that nature "essentially is probabilistic" is an ad hoc assumption, which can never be experimentally tested and thus does not belong to science.
3. Impossibility of knowledge contradicts scientific principle: Why does certain knowledge make other knowledge impossible?
4. Wave-particle duality as contradictory reality, does no make sense.
5. Divison of physics into "classical" and "non-classical" is without reason. Physics is physics.
6. Without division between "classical" and "non-classical", the idea that "non-classical" will approximate "classical", lacks rationale.
I leave to the reader to evaluate the scientific value and rationality of these postulates supposedly expressing the contribution to humanity and the science of physics from what is called "modern physics".