Interpretation of Quantum Flashcards
What are the four postulates of the Copenhagen interpretation?
1) Both the Heisenberg uncertainty principle and the Born rule apply
2) Processes on the atomic scale are inaccessible to measurement
3) The wave function represents everything that can be known about a system, prior to any measurement
4) The act of measurement causes the wave function to collapse
What is the EPR (Einstein-Podolsky-Rosen) interpretation?
Quantum mechanics is an approximation of a deeper underlying theory.
Why did the EPR (Einstein-Podolsky-Rosen) interpretation arise?
The 4th postulate of the Copenhagen interpretation states that a measurement causes the wave function to collapse. However, if two particles are entangled, how could the two ‘communicate’ instantaneously?
How does the path integral formulation describe quantum mechanics?
Classical trajectories are replaced by an integral, that describes an infinite possibility of trajectories between two points. The particle is only localized at these two points.
How does the many worlds interpretation describe quantum?
By observing a system, the observer is entangled in the outcome and decides the ‘branch’ of history the system follows. The ‘collapse’ of the wave function is an observation of the splitting of the history tree - i.e. there are many universes in which all outcomes of the system are possible, but by observing the system the observer ‘chooses’ one.
What are the 3 defining features of the de Broglie-Bohm theory or pilot wave theory?
1) It is deterministic - i.e. a particles’ trajectory can be calculated from its initial position and the wave function
2) This can be written classically as ma = –∂/∂x(V + Q)
3) When particles are entangled during measurement, the superposition of the wave function still exists but ‘leaks’ into the environment
(this is supported by the 2011 experiment of ‘weak’ measurements showing the average trajectories of photons)
