Chapter 5 A clash of doctrines: The arrow of time in modern physics

Peter Mittelstaedt

Sean M. Carroll

This chapter guides the reader through three related enigmas of modern physics. The first is a mystery of quantum mechanics. Important aspects of quantum mechanics are still not truly understood, although competing theories have been proposed, including the Many-Worlds approach. The second enigma is the emergence of spacetime, and especially the way it interacts with gravity. Rather than following the traditional methodology of ‘quantising’ classical theories, the author proposes an alternative approach and instead seeks gravity within quantum mechanics. The chapter concludes with a discussion of the mystery of the arrow of time: what distinguishes the past from the future. Together, these three mysteries of modern physics serve as an important reminder of the endurance of enigmas in the very foundations of scholarly fields. Re-examining founding principles can provide a constructive alternative means of investigating mysteries, not only in modern science but also across other disciplines.

Oleg Kupervasser

The modern classical statistical physics, thermodynamics, quantum mechanics and gravity theory are developed and well-known theories. The described theories are developed and well studied for a long time. Nevertheless, it contains a number of paradoxes. It forces many scientists to doubt internal consistency of these theories. However, the given paradoxes can be resolved within the framework of the existing physics, without introduction of new laws. Further, in this paper we discuss the paradoxes underlying classical statistical physics, thermodynamics, quantum mechanics, and non-quantum and quantum gravities. We suggest the approaches to solution of these paradoxes on basis universal arrow of time. The first one relies on the influence of the external observer (environment), which disrupts the correlations in the system and results in time arrows alignment. The basis of the second one is the limits of self-knowledge of the system in case of the observed system; the external observer and the environment are included in the considered system. We introduce the concepts of observable dynamics, ideal dynamics, and unpredictable dynamics. We contemplate the phenomenon of complex (living) systems from the point of view of these dynamics. Perspectives of practical use of Unpredictable systems for artificial intellect are considered. c Chapter 1. The Universal Arrow of Time: Classical Mechanics. Abstract: Solution of paradox for the entropy increase in reversible systems. Statistical physics cannot explain why the thermodynamic time arrow does exist un- less very special and so it postulates unnatural initial conditions. However, we are ready to state that statistical physics is able to explain why the thermodynamic time arrow is

James B. Hartle

Black, Aaron

Modern physics is built on the assumption that time only moves one way, beginning at the initial boundary (or initial condition), fixed effectively at the Big Bang. Our theories begin at that starting point and evolve from there. Yet the laws of nature work both forward and backward. This one-way view lies at the root of many of physics’ biggest puzzles, like wavefunction collapse, quantum “spookiness,” the arrow of time, and the clash between quantum mechanics and relativity. Two-Boundary Theory (2BT) proposes a minimal correction: the universe is a unique four-dimensional history jointly constrained by two real temporal boundaries, an initial (α) and a final (Ω). No new dynamics or hidden variables are added; the same lawful evolution operates in both directions, and the realized world is the intersection of the forward image of α with the backward image of Ω. From within time, partial knowledge of α and ignorance of Ω make outcomes appear stochastic and the future “open,” though the underlying history is globally deterministic and locally causal. This two-sided admissibility resolves the major paradoxes in a single move: Bell-level correlations arise from whole-trajectory consistency rather than superluminal influence; measurement collapse becomes an epistemic update, not a physical jump; and the arrow of time reflects asymmetric boundary information, not asymmetric law. The analysis preserves unitarity, covariance, and conservation principles intact. The paper confines itself to the conceptual and ontological core of the framework; later work develops the informational field Φ(t) and weighted-operator formalism that implement the same constraint mathematically. The result is an Ockham-minimal, time-symmetric completion of the scientific worldview: one reversible law, two boundaries, one consistent universe.

James B. Hartle