The universe remembers no wavefunction collapse

TL;DR

This paper argues that the universe's quantum state does not require wavefunction collapse, showing that unitary evolution alone can explain quantum outcomes and proposing a measurement scheme consistent with conservation laws.

Contribution

It demonstrates that wavefunction collapse is not necessary by analyzing thought experiments, supporting a unitary-only interpretation of quantum mechanics and proposing a new measurement approach.

Findings

Unitary evolution can account for quantum experiment outcomes.

Standard measurement assumptions lead to unnecessary collapse postulates.

A new measurement scheme compatible with unitarity and conservation laws is proposed.

Abstract

Two thought experiments are analyzed, revealing that the quantum state of the universe does not contain definitive evidence of the wavefunction collapse. The first thought experiment shows that unitary quantum evolution alone can account for the outcomes of any combination of quantum experiments. This is in contradiction with the standard view on quantum measurement, which appeals to the wavefunction collapse, but it is in full agreement with the special state proposal (L.S. Schulman in Phys Lett A 102(9):396-400, 1984; J Stat Phys 42(3):689-719 1986; Time's arrows and quantum measurement, Cambridge University Press, Cambridge 1997) that there are some rare states that account for quantum experiments by unitary evolution alone. The second thought experiment consists in successive measurements, and reveals that the standard quantum measurement scheme predicts violations of the conservation laws. It is shown that the standard view on quantum measurements makes some unnecessary assumptions which lead to the apparent necessity to invoke wavefunction collapse. Once these assumptions are removed, a new hope of a measurement scheme emerges, which, while still having open problems, is compatible with both the unitary evolution and the conservation laws, and suggests means to experimentally distinguish between full unitarity and discontinuous collapse.