PHYSICS · Subjective · Fermi University Physics · Quantum Mechanics · The formalism of quantum mechanics · Density matrices, open systems, entanglement and interpretation
Quantum Mechanics: From the Photon to the Hydrogen Atom, Ch The Schrödinger equation and the Born rule
Problem
A particle is described by Ψ=a−1/2e−∣x∣/a. Its position is measured and the result is x0; measured again immediately afterwards, the result is again x0. One reader argues:“This proves the realist reading is right: the particle really was at x0 all along, sitting there like a coin under a cup, and Ψ only ever described our ignorance of where it was hiding. The repeat measurement just confirms that the same fixed fact was there both times.”Is this reasoning correct? Say what the repeat measurement does and does not establish, and name what kind of evidence, beyond anything in this chapter, would be needed to settle the question this argument thinks has just been settled.