English

Insufficiency of the Quantum State for Deducing Observational Probabilities

High Energy Physics - Theory 2015-05-13 v3 General Relativity and Quantum Cosmology Quantum Physics

Abstract

It is usually assumed that the quantum state is sufficient for deducing all probabilities for a system. This may be true when there is a single observer, but it is not true in a universe large enough that there are many copies of an observer. Then the probability of an observation cannot be deduced simply from the quantum state (say as the expectation value of the projection operator for the observation, as in traditional quantum theory). One needs additional rules to get the probabilities. What these rules are is not logically deducible from the quantum state, so the quantum state itself is insufficient for deducing observational probabilities. This is the measure problem of cosmology.

Keywords

Cite

@article{arxiv.0808.0722,
  title  = {Insufficiency of the Quantum State for Deducing Observational Probabilities},
  author = {Don N. Page},
  journal= {arXiv preprint arXiv:0808.0722},
  year   = {2015}
}

Comments

4 pages, LaTeX, minor changes made in response to the referee's comments

R2 v1 2026-06-21T11:07:51.338Z