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Why Time's Description in Modern Physics is Still Incomplete

Avshalom C. Elitzur, Shahar Dolev

Published Jan 1, 2003• 9 citations
OpenAlex

Abstract

We present some novel results indicating that time's description in present-day physics is deficient. We use Hawking's information-erasure hypothesis to counter his own claim that time's arrow depends only on initial conditions. Next, we propose quantum mechanical experiments that yield inconsistent histories, sug- gesting that not only events but also entire histories might be governed by a more fundamental dynamics. 1. The Stalemate The problem associated with time's nature is well known. It stems from two aspects of time that cannot be reconciled:

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Hidden Determinism, Probability, and Time's Arrow

Hans Primas

In present-day physics the fundamental dynamical laws are taken as a time-translation-invariant and time-reversal-invariant one-parameter groups of automorphisms of the underlying mathematical structure. In this context-independent and empirically inaccessible description there is no past, present or future, hence no distinction between cause and effect. To get the familiar description in terms of causes and effects, the time-reversal symmetry of the fundamental dynamics has to be broken. Thereby one gets two representations, one satisfying the generally accepted rules of retarded causality (no effect can precede its cause). The other one describes the strange rules of advanced causality. For entangled (but not necessarily interacting) quantum systems the arrow of time must have the same direction for all subsystems. But for classical systems, or for classical subsystems of quantum systems, this argument does not hold. As a cosequence, classical systems allow the conceptual possibility of advanced causality in addition to retarded causality. Every mathematically formulated dynamics of statistically reproducible events can be extended to a description in terms of a one-parameter group of automorphisms of an enlarged mathematical structure which describes a fictitious hidden determinism. Consequently, randomness in the sense of mathematical probability theory is only a weak generalization of determinism. The popular ideas that in quantum theory there are gaps in the causal chain which allow the accommodation of the freedom of human action are fantasies which have no basis in present-day quantum mechanics. Quantum events are governed by strict statistical laws. Freedom of action is a constitutive necessity of all experimental science which requires a violation of the statistical predictions of physics. We conclude that the presently adopted first principles of theoretical physics can neither explain the autonomy of the psyche nor account for the freedom of action necessary for experimental science.

•Jan 1, 2002•16 citations

Arrow of Time and Quantum Physics

Detlev Buchholz A, Klaus Fredenhagen

Abstract Based on the hypothesis that the (non-reversible) arrow of time is intrinsic in any system, no matter how small, the consequences are discussed. Within the framework of local quantum physics it is shown how such a semi-group action of time can consistently be extended to that of the group of spacetime translations in Minkowski space. In presence of massless excitations, however, there arise ambiguities in the theoretical extensions of the time translations to the past. The corresponding loss of quantum information on states upon time is determined. Finally, it is explained how the description of operations in classical terms combined with constraints imposed by the arrow of time leads to a quantum theoretical framework. These results suggest that the arrow of time is fundamental in nature and not merely a consequence of statistical effects on which the Second Law is based.

arXiv:2305.11709•Foundations of Physics•Sep 21, 2023•4 citations

The Observer as a Local Breakdown of Atemporality

Giani Moreno Gabriel

The nature of time remains a central problem in fundamental physics, spanning quantum mechanics, thermodynamics, and relativity. In this work, we develop an observer-dependent framework in which time is not assumed as a fundamental background parameter, but emerges operationally from restricted access to a globally timeless quantum state. Building on and extending the Page–Wootters mechanism, we introduce a unified relational formula that shows how three traditionally distinct aspects of temporality arise from the same structure: quantum dynamics from conditioning on physical clock states, thermodynamic irreversibility from partial tracing over inaccessible degrees of freedom, and observer-relative time from the locality of the clock subsystem. No modification of unitary quantum mechanics, collapse postulates, or fundamental time flow is required. Analytical arguments and numerical simulations demonstrate that, in the limit of complete information access, all temporal ordering disappears, while effective Schrödinger dynamics and an arrow of time emerge naturally under informational and observational constraints. These results support a central claim: time is not a property of the universe itself, but a property of descriptions generated by physical observers embedded within it.

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Quantum causality determines the arrow of time

John F. Donoghue, Gabriel Menezes

In the philosophy of science, the origin of an arrow of time is viewed as problematic. We describe here how this arrow really follows from the causal structure of quantum physics. This connection is not really new -- it is just overlooked in most discussions of the arrow of time.

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Queeter Theory: Quantum Underlying Entanglement Event Time Entropy Retention

Jeffrey Alexander Webb

Description The Quantum Underlying Entanglement Event Time–Entropy Retention model, abbreviated QUEETER, is a speculative framework designed to explore whether the history of a quantum entanglement event can continue to influence a system after that event has already occurred. The model begins with the familiar idea that two or more quantum systems can become entangled. When systems are entangled, their properties are connected through correlations that cannot always be explained by treating each system independently. These correlations can remain observable even when the systems are separated.In ordinary quantum theory, the present condition of a system is described by its quantum state. For realistic systems, this state is often represented by a density matrix, which contains the measurable probabilities, coherences, and correlations available at a given time. QUEETER asks whether this present-state description is always sufficient. Its central proposal is that an entanglement event may leave behind a temporary historical influence. This influence would depend on when the entanglement event occurred and on the amount of entropy produced or encountered after that event. The model calls this continuing influence event retention, or QUEETER retention.Under this proposal, an entanglement event is not treated merely as an instantaneous preparation step. Instead, it is treated as the beginning of a history that may continue to affect later quantum behavior. An entanglement event is any physical interaction that creates or significantly changes entanglement between quantum systems. This event could occur through a controlled quantum gate, the emission of correlated particles, a collision, a shared interaction, or another physical process capable of generating quantum entanglement. QUEETER assigns importance to the time at which this event occurs. That moment becomes the starting point for the event’s retention history. As time passes, the event becomes older. During that period, the system may also interact with its environment, experience thermal noise, undergo measurements, lose energy, or participate in other irreversible processes. QUEETER proposes that both the age of the event and the entropy associated with its later history may influence how much of the event’s original historical effect remains.Time is one of the central elements of the QUEETER model. The model proposes that the influence of an entanglement event gradually weakens as the event becomes older. A recently created entangled system may therefore possess a stronger event-retention effect than a system whose entanglement was created much earlier. This does not simply mean that older systems are expected to have less entanglement. That ordinary effect is already explained by decoherence, noise, and other forms of environmental disturbance.The stronger QUEETER claim is that event age may affect future behavior even when two systems have been adjusted so that their present measurable quantum states are the same. In other words, two systems could appear identical at the beginning of an experiment but evolve differently because one system’s entanglement event happened more recently than the other’s.Entropy is the second major historical element in QUEETER. In this context, entropy represents the irreversible spreading, loss, or inaccessibility of information during the system’s history. A quantum system may accumulate entropy through interactions with a thermal environment, uncontrolled noise, scattering, dissipation, measurement-like processes, or other physical mechanisms that distribute information into surrounding degrees of freedom. QUEETER proposes that greater accumulated entropy exposure reduces event retention. This means that two entangled systems of the same age might still possess different retention values if one experienced a more disruptive or entropy-producing history. The model therefore distinguishes between the system’s present environment and its environmental history. Two systems may currently be held at the same temperature, exposed to the same controls, and placed in the same apparatus while still having experienced different amounts of entropy production in the past. QUEETER suggests that this difference in past entropy exposure may influence later quantum evolution.QUEETER retention is the proposed remaining influence of the original entanglement event. It is not meant to be identical to entanglement itself. A system may still be entangled even after its QUEETER retention has become very small. Similarly, a nonzero retention value would not automatically prove that the system remains strongly entangled. Entanglement refers to a property of the quantum state, while retention refers to the proposed continuing effect of the event history that created or shaped that state. Retention is also not intended to be the same as ordinary coherence. Quantum coherence describes phase relationships that are already visible in the present quantum state. QUEETER retention is meant to carry information about the event’s age and entropy history, even when that information is not directly visible through ordinary measurements of the present reduced state. The model treats retention as an additional descriptive variable. This variable would be strongest near the time of the entanglement event and would gradually fade as time passes and entropy accumulates.Decoherence describes how quantum coherence and entanglement become weakened when a system interacts with its environment. It explains why quantum behavior becomes difficult to observe in large, warm, or uncontrolled systems. QUEETER does not replace decoherence. Instead, it proposes that the rate or pattern of decoherence may temporarily depend on the retained history of the original entanglement event.In the basic protective version of the model, greater retention slightly slows the loss of observable quantum correlations. As retention fades, the system’s behavior gradually returns to the ordinary decoherence rate. This produces the prediction that a recently entangled system may lose correlations differently from an older but otherwise matched system. However, simply observing different decay rates would not be enough to support QUEETER. Ordinary environmental differences can easily produce such an effect. The systems would need to be carefully matched and tested under the same present conditions.Quantum memory refers to a physical system or degree of freedom that stores quantum information. Examples include atomic ensembles, trapped particles, optical systems, or environmental modes that preserve information about earlier interactions. QUEETER retention is intended to be conceptually different. It is not initially described as a separate physical storage device or memory qubit. It is described as a property associated with the entanglement event and its history. This distinction is difficult to maintain scientifically. If the proposed retention effect can be explained by an unnoticed environmental memory, then QUEETER would not require a new physical theory. It would instead represent a different way of describing an already known memory process. For QUEETER to become genuinely distinct, it would need to predict something that cannot be reproduced by including the relevant environment and memory degrees of freedom in an ordinary quantum model.Non-Markovian quantum dynamics describes situations in which the future behavior of a system depends on its earlier interactions. In a simple memoryless process, the future depends only on the present state. In a non-Markovian process, information can flow between the system and the environment, allowing earlier events to influence later behavior. This area of physics is closely related to the idea behind QUEETER.For that reason, QUEETER cannot claim originality merely because it introduces history-dependent quantum behavior. That general idea is already well established. The proposed distinction is more specific. QUEETER suggests that the time and entropy history of a particular entanglement event may act as an additional effective state variable, even when the ordinary present quantum state and the relevant present environment have been matched. This is a much stronger claim because it suggests that the conventional description may be incomplete unless the event-retention history is included.The basic test of QUEETER uses two groups of entangled quantum systems. The first group has a recent entanglement-event history. The second group has an older entanglement-event history or has experienced more entropy-producing interactions. At first, the groups would naturally have different present states because the older or more disturbed group may have suffered more decoherence. To make the experiment meaningful, researchers would need to match the present quantum states of the two groups. This could involve carefully controlled noise, filtering, state preparation, or other procedures that bring both groups to nearly the same measured density matrix. The experimenters would then place both groups in the same test environment. They would expose the systems to the same controls, the same temperature, the same noise conditions, the same measurement schedule, and the same observation period.The later quantum correlations of the two groups would then be measured. Under the conventional null hypothesis, systems with the same complete relevant state and the same dynamics should produce the same future measurement statistics. Under QUEETER, the systems may evolve differently because their event-retention values are different.The primary QUEETER prediction is that two systems with nearly identical present quantum states may display different future correlation-decay behavior if their entanglement-event histories differ. In the protective version of the model, the system with the more recent and lower-entropy history retains its correlations for slightly longer.

•Jul 26, 2026•0 citations

On the Incompleteness of Physics: Time as a Fundamental Misconception

Yu, Liang

We argue that modern physics—including classical mechanics, relativity, and quantum mechanics—suffers from a fundamental incompleteness rooted in the treatment of time as a variable. Starting from parity violation and the absence of intrinsic lifetime in quantum wave functions, we show that: (1) only matter can observe change, yet physics uses light (which has no time) to define spacetime; (2) the time coordinate is either meaningless (without motion) or not independent (with motion); (3) physics writes equations from a God's eye view but performs measurements from a material observer's view; (4) matter, change, and time form a circular dependency that cannot be resolved within the current framework. The incompleteness of physics is not technical but structural.

•Jan 18, 2026•0 citations
We present some novel results indicating that time's description in present-day physics is deficient. We use Hawking's information-erasure hypothesis to counter his own claim that time's arrow depends only on initial conditions. Next, we propose quantum mechanical experiments that yield inconsistent histories, sug- gesting that not only events but also entire histories might be governed by a more fundamental dynamics. 1. The Stalemate The problem associated with time's nature is well known. It stems from two aspects of time that cannot be reconciled:
In present-day physics the fundamental dynamical laws are taken as a time-translation-invariant and time-reversal-invariant one-parameter groups of automorphisms of the underlying mathematical structure. In this context-independent and empirically inaccessible description there is no past, present or future, hence no distinction between cause and effect. To get the familiar description in terms of causes and effects, the time-reversal symmetry of the fundamental dynamics has to be broken. Thereby one gets two representations, one satisfying the generally accepted rules of retarded causality (no effect can precede its cause). The other one describes the strange rules of advanced causality. For entangled (but not necessarily interacting) quantum systems the arrow of time must have the same direction for all subsystems. But for classical systems, or for classical subsystems of quantum systems, this argument does not hold. As a cosequence, classical systems allow the conceptual possibility of advanced causality in addition to retarded causality. Every mathematically formulated dynamics of statistically reproducible events can be extended to a description in terms of a one-parameter group of automorphisms of an enlarged mathematical structure which describes a fictitious hidden determinism. Consequently, randomness in the sense of mathematical probability theory is only a weak generalization of determinism. The popular ideas that in quantum theory there are gaps in the causal chain which allow the accommodation of the freedom of human action are fantasies which have no basis in present-day quantum mechanics. Quantum events are governed by strict statistical laws. Freedom of action is a constitutive necessity of all experimental science which requires a violation of the statistical predictions of physics. We conclude that the presently adopted first principles of theoretical physics can neither explain the autonomy of the psyche nor account for the freedom of action necessary for experimental science.
Abstract Based on the hypothesis that the (non-reversible) arrow of time is intrinsic in any system, no matter how small, the consequences are discussed. Within the framework of local quantum physics it is shown how such a semi-group action of time can consistently be extended to that of the group of spacetime translations in Minkowski space. In presence of massless excitations, however, there arise ambiguities in the theoretical extensions of the time translations to the past. The corresponding loss of quantum information on states upon time is determined. Finally, it is explained how the description of operations in classical terms combined with constraints imposed by the arrow of time leads to a quantum theoretical framework. These results suggest that the arrow of time is fundamental in nature and not merely a consequence of statistical effects on which the Second Law is based.
The nature of time remains a central problem in fundamental physics, spanning quantum mechanics, thermodynamics, and relativity. In this work, we develop an observer-dependent framework in which time is not assumed as a fundamental background parameter, but emerges operationally from restricted access to a globally timeless quantum state. Building on and extending the Page–Wootters mechanism, we introduce a unified relational formula that shows how three traditionally distinct aspects of temporality arise from the same structure: quantum dynamics from conditioning on physical clock states, thermodynamic irreversibility from partial tracing over inaccessible degrees of freedom, and observer-relative time from the locality of the clock subsystem. No modification of unitary quantum mechanics, collapse postulates, or fundamental time flow is required. Analytical arguments and numerical simulations demonstrate that, in the limit of complete information access, all temporal ordering disappears, while effective Schrödinger dynamics and an arrow of time emerge naturally under informational and observational constraints. These results support a central claim: time is not a property of the universe itself, but a property of descriptions generated by physical observers embedded within it.
Description The Quantum Underlying Entanglement Event Time–Entropy Retention model, abbreviated QUEETER, is a speculative framework designed to explore whether the history of a quantum entanglement event can continue to influence a system after that event has already occurred. The model begins with the familiar idea that two or more quantum systems can become entangled. When systems are entangled, their properties are connected through correlations that cannot always be explained by treating each system independently. These correlations can remain observable even when the systems are separated.In ordinary quantum theory, the present condition of a system is described by its quantum state. For realistic systems, this state is often represented by a density matrix, which contains the measurable probabilities, coherences, and correlations available at a given time. QUEETER asks whether this present-state description is always sufficient. Its central proposal is that an entanglement event may leave behind a temporary historical influence. This influence would depend on when the entanglement event occurred and on the amount of entropy produced or encountered after that event. The model calls this continuing influence event retention, or QUEETER retention.Under this proposal, an entanglement event is not treated merely as an instantaneous preparation step. Instead, it is treated as the beginning of a history that may continue to affect later quantum behavior. An entanglement event is any physical interaction that creates or significantly changes entanglement between quantum systems. This event could occur through a controlled quantum gate, the emission of correlated particles, a collision, a shared interaction, or another physical process capable of generating quantum entanglement. QUEETER assigns importance to the time at which this event occurs. That moment becomes the starting point for the event’s retention history. As time passes, the event becomes older. During that period, the system may also interact with its environment, experience thermal noise, undergo measurements, lose energy, or participate in other irreversible processes. QUEETER proposes that both the age of the event and the entropy associated with its later history may influence how much of the event’s original historical effect remains.Time is one of the central elements of the QUEETER model. The model proposes that the influence of an entanglement event gradually weakens as the event becomes older. A recently created entangled system may therefore possess a stronger event-retention effect than a system whose entanglement was created much earlier. This does not simply mean that older systems are expected to have less entanglement. That ordinary effect is already explained by decoherence, noise, and other forms of environmental disturbance.The stronger QUEETER claim is that event age may affect future behavior even when two systems have been adjusted so that their present measurable quantum states are the same. In other words, two systems could appear identical at the beginning of an experiment but evolve differently because one system’s entanglement event happened more recently than the other’s.Entropy is the second major historical element in QUEETER. In this context, entropy represents the irreversible spreading, loss, or inaccessibility of information during the system’s history. A quantum system may accumulate entropy through interactions with a thermal environment, uncontrolled noise, scattering, dissipation, measurement-like processes, or other physical mechanisms that distribute information into surrounding degrees of freedom. QUEETER proposes that greater accumulated entropy exposure reduces event retention. This means that two entangled systems of the same age might still possess different retention values if one experienced a more disruptive or entropy-producing history. The model therefore distinguishes between the system’s present environment and its environmental history. Two systems may currently be held at the same temperature, exposed to the same controls, and placed in the same apparatus while still having experienced different amounts of entropy production in the past. QUEETER suggests that this difference in past entropy exposure may influence later quantum evolution.QUEETER retention is the proposed remaining influence of the original entanglement event. It is not meant to be identical to entanglement itself. A system may still be entangled even after its QUEETER retention has become very small. Similarly, a nonzero retention value would not automatically prove that the system remains strongly entangled. Entanglement refers to a property of the quantum state, while retention refers to the proposed continuing effect of the event history that created or shaped that state. Retention is also not intended to be the same as ordinary coherence. Quantum coherence describes phase relationships that are already visible in the present quantum state. QUEETER retention is meant to carry information about the event’s age and entropy history, even when that information is not directly visible through ordinary measurements of the present reduced state. The model treats retention as an additional descriptive variable. This variable would be strongest near the time of the entanglement event and would gradually fade as time passes and entropy accumulates.Decoherence describes how quantum coherence and entanglement become weakened when a system interacts with its environment. It explains why quantum behavior becomes difficult to observe in large, warm, or uncontrolled systems. QUEETER does not replace decoherence. Instead, it proposes that the rate or pattern of decoherence may temporarily depend on the retained history of the original entanglement event.In the basic protective version of the model, greater retention slightly slows the loss of observable quantum correlations. As retention fades, the system’s behavior gradually returns to the ordinary decoherence rate. This produces the prediction that a recently entangled system may lose correlations differently from an older but otherwise matched system. However, simply observing different decay rates would not be enough to support QUEETER. Ordinary environmental differences can easily produce such an effect. The systems would need to be carefully matched and tested under the same present conditions.Quantum memory refers to a physical system or degree of freedom that stores quantum information. Examples include atomic ensembles, trapped particles, optical systems, or environmental modes that preserve information about earlier interactions. QUEETER retention is intended to be conceptually different. It is not initially described as a separate physical storage device or memory qubit. It is described as a property associated with the entanglement event and its history. This distinction is difficult to maintain scientifically. If the proposed retention effect can be explained by an unnoticed environmental memory, then QUEETER would not require a new physical theory. It would instead represent a different way of describing an already known memory process. For QUEETER to become genuinely distinct, it would need to predict something that cannot be reproduced by including the relevant environment and memory degrees of freedom in an ordinary quantum model.Non-Markovian quantum dynamics describes situations in which the future behavior of a system depends on its earlier interactions. In a simple memoryless process, the future depends only on the present state. In a non-Markovian process, information can flow between the system and the environment, allowing earlier events to influence later behavior. This area of physics is closely related to the idea behind QUEETER.For that reason, QUEETER cannot claim originality merely because it introduces history-dependent quantum behavior. That general idea is already well established. The proposed distinction is more specific. QUEETER suggests that the time and entropy history of a particular entanglement event may act as an additional effective state variable, even when the ordinary present quantum state and the relevant present environment have been matched. This is a much stronger claim because it suggests that the conventional description may be incomplete unless the event-retention history is included.The basic test of QUEETER uses two groups of entangled quantum systems. The first group has a recent entanglement-event history. The second group has an older entanglement-event history or has experienced more entropy-producing interactions. At first, the groups would naturally have different present states because the older or more disturbed group may have suffered more decoherence. To make the experiment meaningful, researchers would need to match the present quantum states of the two groups. This could involve carefully controlled noise, filtering, state preparation, or other procedures that bring both groups to nearly the same measured density matrix. The experimenters would then place both groups in the same test environment. They would expose the systems to the same controls, the same temperature, the same noise conditions, the same measurement schedule, and the same observation period.The later quantum correlations of the two groups would then be measured. Under the conventional null hypothesis, systems with the same complete relevant state and the same dynamics should produce the same future measurement statistics. Under QUEETER, the systems may evolve differently because their event-retention values are different.The primary QUEETER prediction is that two systems with nearly identical present quantum states may display different future correlation-decay behavior if their entanglement-event histories differ. In the protective version of the model, the system with the more recent and lower-entropy history retains its correlations for slightly longer.
We argue that modern physics—including classical mechanics, relativity, and quantum mechanics—suffers from a fundamental incompleteness rooted in the treatment of time as a variable. Starting from parity violation and the absence of intrinsic lifetime in quantum wave functions, we show that: (1) only matter can observe change, yet physics uses light (which has no time) to define spacetime; (2) the time coordinate is either meaningless (without motion) or not independent (with motion); (3) physics writes equations from a God's eye view but performs measurements from a material observer's view; (4) matter, change, and time form a circular dependency that cannot be resolved within the current framework. The incompleteness of physics is not technical but structural.