The issue with the initial state in quantum mechanics

TL;DR

This paper argues that the initial state in quantum mechanics should include the experimenter's state for a complete description, enabling joint probabilities and addressing issues of meaningfulness in past event statements.

Contribution

It proposes a reformulation of quantum mechanics that incorporates the experimenter's state into the initial description, providing a more complete and consistent framework.

Findings

Allows joint probabilities for observed events

Addresses the meaning of past events in quantum mechanics

Highlights limitations of conventional initial state assumptions

Abstract

In the conventional formulation of quantum mechanics, the initial description is given only for the physical system under study. It factors out the state for the experimenter. We argue that such description is incomplete and can lead to statements which can in theory be meaningless. We propose that within a complete description, the initial state must include the state of the experimenter. With such formulation quantum mechanics provides joint probabilities for conjointly observed events, rather than a probability conditional on some initial state for the system under study. This feature is desirable, as with quantum mechanics, statements on what happened in the past may have no meaning in the present.