In the book the idea of irreversibility as an inherent property of time is developed theoretically and experimentally. The matter is related with causality, and the method of causal analysis is presented. The quantum causal analysis helps understand the principle of week causality which admits extraction of information from the future without the classical paradoxes. It implies a possibility of observation of the future as the existing reality. So, the acceptance of time irreversibility leads to a striking manifestation of reversibility – signaling in reverse time. Quantum insight allows considering correlations of the distant irreversible processes as nonlocal ones originated from a macroscopic entanglement. The experimental approach to study of macroscopic nonlocality is discussed, and design of the experimental setup is described. The results of experiments on macroscopic nonlocal correlations, the signals in reverse time and their application to the forecast of large-scale random processes are expounded.In the book the idea of irreversibility as an inherent property of time is developed theoretically and experimentally. The matter is related with causality, and the method of causal analysis is presented. The quantum causal analysis helps understand the principle of week causality which admits extraction of information from the future without the classical paradoxes. It implies a possibility of observation of the future as the existing reality. So, the acceptance of time irreversibility leads to a striking manifestation of reversibility – signaling in reverse time. Quantum insight allows considering correlations of the distant irreversible processes as nonlocal ones originated from a macroscopic entanglement. The experimental approach to study of macroscopic nonlocality is discussed, and design of the experimental setup is described. The results of experiments on macroscopic nonlocal correlations, the signals in reverse time and their application to the forecast of large-scale random processes are expounded.

Jan 1, 201110 citations

Advanced response of Baikal macroscopic nonlocal correlation detector to solar activity

Sergey M. Korotaev, N. M. Budnev, V. O. Serdyuk

The long-term Baikal Deep-Sea Experiment on study of macroscopic entanglement and advanced response of nonlocal correlation detectors to natural random dissipative processes is conducting. There are both advanced and retarded nonlocal correlations, which correspond to the same direction of causality. However, time reversal causality prevails over usual time respecting one. It is the most prominent property of macroscopic entanglement and manifestation of quantum principle of weak causality. In particular, there is an advanced response to the random component of solar activity, which can be used for the forecast of this component.The long-term Baikal Deep-Sea Experiment on study of macroscopic entanglement and advanced response of nonlocal correlation detectors to natural random dissipative processes is conducting. There are both advanced and retarded nonlocal correlations, which correspond to the same direction of causality. However, time reversal causality prevails over usual time respecting one. It is the most prominent property of macroscopic entanglement and manifestation of quantum principle of weak causality. In particular, there is an advanced response to the random component of solar activity, which can be used for the forecast of this component.

Journal of Physics Conference SeriesNov 1, 20174 citations

Irreversibility and Mechanics

Karl Raimund Popper

NatureAug 18, 195625 citations

Irreversibility and Mechanics

Richard Schlegel

NatureAug 1, 19563 citations

Temporal Coarse-Graining as the Origin of Macroscopic Friction in Quantum Spin Chains via Data-Driven Liouvillian Extraction

Seiki Saito

Understanding how macroscopic irreversible hydrodynamics emerges from the reversible unitary dynamics of isolated quantum many-body systems remains a central challenge. Conventional approaches force spin density dynamics into purely diffusive models, obscuring the interplay of pressure, spin current, and local friction, and leave open the role of the observer's temporal resolution. We introduce a fully data-driven framework based on generalized Extended Dynamic Mode Decomposition (gEDMD) integrated with the Mori-Zwanzig projection. By expanding the observable dictionary to include spin currents, we extract the Navier-Stokes hydrodynamic coefficients from a chaotic XXZ spin chain across temporal coarse-graining scales. Our unconstrained extraction reveals a dichotomy: the mechanical elasticity ( $c^2$ ) derives from the exact unitary dynamics, preserving microscopic reversibility, whereas the macroscopic friction ( $γ$ ) and kinematic viscosity ( $ν$ ) show zero net dissipation, oscillating rapidly around zero in the exact-derivative limit. Genuine macroscopic transport therefore requires finite temporal coarse-graining: at a finite observation timescale ( $Δt_{cg} > 0$ ) the system passes through a crossover where these fluctuations average out, establishing an intermediate functional regime with strictly positive friction and viscosity. We further show that the coarse-grained generator is a predictive reduced model requiring only $O(N)$ macroscopic observables, and that the sign of the emergent friction is inherited from the causal, forward-in-time direction of the inference: time-symmetric estimators yield zero net dissipation at any coarse-graining scale. Macroscopic friction in isolated quantum systems is thus not an absolute property but an emergent phenomenon dictated by the temporal resolution and causal direction of the observer's description.Understanding how macroscopic irreversible hydrodynamics emerges from the reversible unitary dynamics of isolated quantum many-body systems remains a central challenge. Conventional approaches force spin density dynamics into purely diffusive models, obscuring the interplay of pressure, spin current, and local friction, and leave open the role of the observer's temporal resolution. We introduce a fully data-driven framework based on generalized Extended Dynamic Mode Decomposition (gEDMD) integrated with the Mori-Zwanzig projection. By expanding the observable dictionary to include spin currents, we extract the Navier-Stokes hydrodynamic coefficients from a chaotic XXZ spin chain across temporal coarse-graining scales. Our unconstrained extraction reveals a dichotomy: the mechanical elasticity ($c^2$) derives from the exact unitary dynamics, preserving microscopic reversibility, whereas the macroscopic friction ($γ$) and kinematic viscosity ($ν$) show zero net dissipation, oscillating rapidly around zero in the exact-derivative limit. Genuine macroscopic transport therefore requires finite temporal coarse-graining: at a finite observation timescale ($Δt_{cg} > 0$) the system passes through a crossover where these fluctuations average out, establishing an intermediate functional regime with strictly positive friction and viscosity. We further show that the coarse-grained generator is a predictive reduced model requiring only $O(N)$ macroscopic observables, and that the sign of the emergent friction is inherited from the causal, forward-in-time direction of the inference: time-symmetric estimators yield zero net dissipation at any coarse-graining scale. Macroscopic friction in isolated quantum systems is thus not an absolute property but an emergent phenomenon dictated by the temporal resolution and causal direction of the observer's description.

quant-pharXiv:2605.05604Physical Review ResearchMay 8, 20260 citations

c^2

) derives from the exact unitary dynamics, preserving microscopic reversibility, whereas the macroscopic friction (

γ

) and kinematic viscosity (

ν

) show zero net dissipation, oscillating rapidly around zero in the exact-derivative limit. Genuine macroscopic transport therefore requires finite temporal coarse-graining: at a finite observation timescale (

Δt_{cg} > 0

) the system passes through a crossover where these fluctuations average out, establishing an intermediate functional regime with strictly positive friction and viscosity. We further show that the coarse-grained generator is a predictive reduced model requiring only

O(N)

macroscopic observables, and that the sign of the emergent friction is inherited from the causal, forward-in-time direction of the inference: time-symmetric estimators yield zero net dissipation at any coarse-graining scale. Macroscopic friction in isolated quantum systems is thus not an absolute property but an emergent phenomenon dictated by the temporal resolution and causal direction of the observer's description.