Quantum theorists look to decipher meaning from their equations as if pondering mystical runes. They do so blithely, from a perspective divorced from the mechanics of actualization.
Nature coherently and emergently appears in Planck-time rhythm from the quantum level up. All the information of existence is incorporated instantaneously, including information about the determinate future. The concept of a “determinate future” follows Fermat’s principle of least time and Hamilton’s principle of least action. These principles are universally incorporated by physicists into their models via Lagrangian, Hamiltonian, and canonical quantization methods.
Most theoretical discussions of causality posit that the laws of physics are mute on the flow of time. American physicist John Donoghue and Brazilian physicist Gabriel Menezes find instead that “hidden in our conventions for quantization is a connection to the definition of an arrow of causality, i.e., what is the past and what is the future. We also note that the ‘thermodynamic arrow of time’, which describes the direction of the increase of entropy, follows the direction of causal processes.”
The seeming indifference of physics to time is found in the symmetry inherent in model equations. Donoghue & Menezes: “Classical fields are real. The probabilities of quantum mechanics are absolute values squared. Measurements in physics do not seem to care if we define √-1 as +i or –i.”
The actualization of modeled phenomena requires spontaneous symmetry breaking and renormalization. The ambiguity between +i and –i must resolve for Nature to transpire. Donoghue & Menezes: “There is an implied arrow of causality built into our description of causal processes. It is connected to the signs in front of the various manifestations of i.”
Time is a product of memory. Causality is an imagined linkage between a perceived action and a subsequent activity which is construed as reaction. The ideas of temporal flow and cause and effect emanate from mentation.
In embracing an ambiguity in interpretation of √-1, physics models are inherently non-denominational with regard to time and its attendant construals. To properly assimilate temporality into models necessitates inclusion of consciousness and mentation. Theories of relativity implicitly do so through their use of perceptual reference frames. That quantum mechanical models, especially those which grapple with quantum gravity, do not incorporate perception is a facet of their incompleteness. Spacetime and its contents are fundamentally defined by their comprehension.
John F. Donoghue & Gabriel Menezes, “The arrow of causality and quantum gravity,” Physical Review Letters (24 October 2019).
Ingrid Fadelli, “New research synthesizes different aspects of causality in quantum field theory,” Phys.org (8 November 2019).