‘Standard quantum mechanics’: the Copenhagen interpretation
“A philosophical extravaganza dictated by despair” (Schr¨odinger)
1. System completely described by wave function representing observer’s knowledge of the system, or ‘potentiality’. The wave function is all there is. ‘Hidden variables’ impossible. (Heisenberg)
2. Description of nature essentially probabilistic. Probability of event related to square of amplitude of wave function related to it (Born rule). ‘Measurement’ randomly picks out exactly one of the many possibilities allowed for by the state’s wave function through nonlocal ‘collapse process’.
3. Heisenberg’s uncertainty principle: observed fact that it is not possible to know values of all properties of system at same time; those properties not known with precision must be described by probabilities. Properties in fact supposed to be indeterminate not uncertain.
4. Complementarity principle: there is no logical picture (obeying classical propositional logic) that can simultaneously describe and be used to reason about all properties of a quantum system. Example: matter exhibits a wave-particle duality. An experiment can show the particle-like properties of matter, or wave-like properties, but not both at the same time. (Niels Bohr)
5. Measuring devices are essentially classical devices, and measure classical properties such as position and momentum.
6. The ‘correspondence principle’ of Bohr and Heisenberg: the quantum mechanical description of large systems should closely approximate to the classical description.
Now well-known that Copenhagen cannot be reconstructed as a coherent
philosophical framework - it is a collection of local, often contradictory, arguments
embedded in changing theoretical and sociopolitical circumstances.. ..riddled with
vaccillations, about-faces and inconsistencies. [See Mara Beller book ‘Quantum Dialogue’]
- Towler Bohm Lecture 1
On Jul 16, 2012, at 3:14 AM, JACK SARFATTI wrote:
Michael Towler wrote about Bohr:
"(Circular) demonstrations of consistency disguised as compelling arguments of inevitability. [Those who do not agree are] ‘unable to face the facts’ and disagreeing with the masters of the universe thus becomes bad for your career.”
in his Cambridge lectures on Bohm’s quantum theory
Well and good, but the same flaw is found in the proofs prohibiting entanglement signaling.
The no-cloning theorem is incomplete. It only forbids a small class of devices like Nick Herbert’s FLASH based on linearity and unitarity.
There are other ways to skin Schrodinger’s Cat.