From Unitarity to Irreversibility: The Role of Infinite Tensor Products and Nested Wigner’s Friends

Svozil, Karl

doi:10.1007/s10701-025-00903-9

Record link:

http://hdl.handle.net/20.500.12708/227701

Title:

From Unitarity to Irreversibility: The Role of Infinite Tensor Products and Nested Wigner’s Friends

Citation:

Svozil, K. (2026). From Unitarity to Irreversibility: The Role of Infinite Tensor Products and Nested Wigner’s Friends. Foundations of Physics, 56(1), Article 4. https://doi.org/10.1007/s10701-025-00903-9

Publisher DOI:

10.1007/s10701-025-00903-9

CatalogPlus:

AC17845378

Publication Type:

Article - Original Research Article

Language:

English

Authors:

Svozil, Karl

Organisational Unit:

E136 - Institut für Theoretische Physik

Journal:

Foundations of Physics

ISSN:

0015-9018

Date (published):

Feb-2026

Number of Pages:

Publisher:

SPRINGER

Peer reviewed:

Yes

Keywords:

Infinite tensor products; Irreversibility; Nested Wigner’s friend; Quantum decoherence; Quantum entanglement; Quantum measurement; Von Neumann algebras

Abstract:

The transition from unitary, reversible von Neumann-Everett quantum processes to non-unitary, irreversible processes and measurements is explored through infinite tensor products interpreted as nested, chained, or iterated Wigner’s friend scenarios. Infinite tensor products can disrupt unitary equivalence through sectorization and factorization, drawing parallels to concepts from real analysis, recursive mathematics, and statistical physics.

Project title:

Orthogonalität und Symmetrie: PIN5424624 (FWF - Österr. Wissenschaftsfonds)

Research Areas:

Design and Engineering of Quantum Systems: 100%

Science Branch:

1030 - Physik, Astronomie: 100%

License:

CC BY 4.0