With Einstein’s interpretation, “everything is relative”, the so-called twin experiment discloses what is called a paradox, when the travelling twin returns and they compare watches (and aging). Some assign the solution to acceleration, which they claim should be taken into account so that the paradox evaporates. However, it’s easy to construct an experiment in which any acceleration lays outside the considered part of the experiment, so that within the measured part we have only constant velocities. We can then have one observer at rest, and two travelers who run through the travelling twin’s route, but without acceleration. Within a hypothetical absolute underlying medium, particles oscillate slower for an observer who moves through the Aether than they do for an observer at rest. An acceleration free experiment can be made in which all three agree on that. The conflict appears if the traveling ‘twins’ measure how fast the first observers clock runs, based on their respective lines of simultaneity, because then the travelling ‘twins’ then insist that A’s particles oscillate slower than their own. Even without the physical experiment, the thought experiment itself discloses that the twin-paradox is a product of the “everything is relative” interpretation.
Abstract In the twin paradox of special relativity, an observer that travels along an accelerated trajectory at a high velocity will experience a smaller amount of elapsed time than an observer that remains at rest. This illustrates the fact that time is relative unlike the situation in classical physics where time is absolute. In a recent paper, Bushev et al (2016 New J. Phys. 18 093050 ) showed that the twin paradox can also be demonstrated using a single electron that functions as a quantum-mechanical clock. The wave function of the electron can travel along two different paths simultaneously, which allows a measurement of the difference in proper times along the two trajectories using a single particle. Quantum interference effects show that time cannot be thought of as a classical parameter even when associated with a single clock or observer.
The Classical Twin Paradox is widely dealt in literature and neatly resolved. In addition, it is also well known that, when looking at two systems which are boosted relative to each other, the concept of the simultaneous effect of a quantum measurement in space-time causes some discrepancies in the cause-effect behavior. However, these discrepancies have been thought not to cause any apparent paradox except for violating the Free-Will postulate. In this paper we suggest that using the local t axis, all over space, as the axis in which the quantum measurement is thought to be simultaneous, we do reach a kind of true "Twin Paradox". The resolution of this paradox requires the introduction of a global proper time into a covariant quantum theory.
Abstract In their recent articles Gruber, Block and Montemayor (2022: Front. Psychol., 13, 718505) and Buonomano and Rovelli (2022: arXiv:2110.01976) discuss the differences between time in physics and psychology. With the aim of commenting on their views, we first outline a few general aspects of relativity theory, and some of the core elements of our approach, referring the reader to Aerts (1996: Found. Phys., 26, 1627–1644; 2018: Found. Sci., 23, 511–547), Aerts and Aerts (2004: in A. C. Elitzur, S. Dolev and N. Kolenda (Eds), Quo Vadis Quantum Mechanics? Possible Developments in Quantum Theory in the 21st Century, pp. 153–207) and Aerts and Sassoli de Bianchi (2023: arXiv:2307.04764) for more details. In our approach, the ability of the experimenter to freely choose to perform or not to perform an experiment is explicitly considered and applied to the typical twin-paradox situation. This leads to the definition of a four-dimensional spacetime reality for each observer, a personal block universe. This is compatible with the existence of a local contextual present for each observer, travelling on their worldline, from their personal past to their personal future. Global spacetime becomes, as a corollary, a structure full of measurement-induced bifurcations towards the future, thus fundamentally nondeterministic. We analyze and highlight how this nondeterministic global reality is the one that follows from an operational approach inspired by quantum foundations, opening a way for an integration of relativity and quantum.
The treatment of time in relativity does not conform to that in quantum theory. In the context of quantum gravity this is called "the problem of time". A crucial difference is that time
t may be seen as an observable in relativity theory, just like position
x, whereas in quantum theory
t is a parameter, in contrast to the observable
x. Aiming to resolve the discrepancy, a formalization of time in the spirit of Kant's Copernican revolution is suggested, where it is required that the treatment of time in physics agree with our cognition. This leads to reconsideration of the notions of identity and change of objects, as well as the nature of physical states and their evolution. The formalization has two components: sequential time
n and relational time
t. The evolution of physical states is described in terms of
n, which is updated each time an event occurs. The role of
t is to quantify distances between events in space-time. There is a space-time associated with each
n, in which
t represents the knowledge at time
n about temporal distances between present and past events. A universal ordering of events in terms of
n can be postulated even though distances
t are relativistic. In short, it is argued that time as a sequential flow of events should be separated from time as a measure of distance between events. In physical models, these aspects of time can be expressed as one evolution parameter and one observable, respectively.
We propose a novel framework for understanding quantum entanglement as a phenomenon fundamentally dependent on the proper-time histories of entangled particles. Drawing an analogy to the classical twin paradox of special relativity, we hypothesize that entanglement persists only when particle worldlines remain synchronized in their accumulated proper time. When differential aging occurs due to relative velocity or gravitational time dilation, quantum correlations degrade in a predictable, oscillatory manner. This “Entangled Twin Paradox” makes testable predictions that distinguish it from standard quantum mechanics, which treats entanglement as independent of relativistic effects.