In the theory of special relativity, a particle that has rest mass with subluminal velocity needs infinite energy to accelerate to the speed of light. Special relativity does not prohibit the existence of particles that travel faster than light. In arXiv:1303.0614 quantum entanglement was measured at 10,000 times the speed of light or 4 orders of magnitude the speed of light or 2.99 E 12 m/s 2. At the quantum level some believe that retrocausality is forbidden. The purpose of this paper is to show how an email message can go proportionally faster than light to report on an event from the present into the past. The event reported from the present is sent into the past in the Inbox history instantaneously and a copy of the email that is (-) 2.7 hours in the past will also be sent to the Inbox history. Whether or not the event reported from the present that is sent into the past can be changed is not the purpose of this paper. The purpose of this paper is to show how a message from now can report on an event from now and sent into the past.(retrocausal communication)
In the theory of special relativity, a particle that has rest mass with subluminal velocity needs infinite energy to accelerate to the speed of light. Special relativity does not prohibit the existence of particles that travel faster than light. In arXiv:1303.0614 quantum entanglement was measured at 10,000 times the speed of light or 4 orders of magnitude the speed of light or 2.99 E 12 m/s 2. At the quantum level some believe that retrocausality is forbidden. The purpose of this paper is to show how an email message can go proportionally faster than light to report on an event from the present into the past. The event reported from the present is sent into the past in the Inbox history instantaneously and a copy of the email that is (-) 2.7 hours in the past will also be sent to the Inbox history. Whether or not the event reported from the present that is sent into the past can be changed is not the purpose of this paper. The purpose of this paper is to show how a message from now can report on an event from now and sent into the past.(retrocausal communication)
Two statements in physics are frequently conflated: that nothing can travel faster than light, and that two entangled particles behave as if "instantaneously" connected regardless of their separation. This paper addresses both questions together: whether a faster-than-light particle could exist and, if so, whether it would count as matter; and whether quantum entanglement actually violates the light-speed limit. Starting from the energy–velocity relation of special relativity, it is shown that massive particles cannot reach the speed of light, and the properties of hypothetical tachyons (imaginary mass, absence of a rest frame and violation of causality) are examined. Using the singlet state, the non-separability, reduced state and correlation properties of entanglement are derived, and the quantum violation of the CHSH inequality up to 2√2 is computed. Finally, via the no-signaling theorem, it is shown that entanglement produces non-local correlations without permitting superluminal communication. In conclusion, nature accommodates non-local correlations without allowing any object to travel faster than light.
This paper presents a conceptual and analytical investigation into the limits of temporal access through the combined perspectives of causality, relativity, quantum mechanics, thermodynamics, and information theory. The work introduces the concept of the “Temporal Causality Barrier,” a selective and logically grounded framework that distinguishes between passive temporal observation and active temporal intervention. The paper argues that passive observation of the past is both physically permissible and continuously occurring through ordinary causal processes such as light propagation, memory, historical records, and astronomical observation. In contrast, active intervention into the past including backward information transfer, causal alteration of previous events, and closed causal loops is shown to generate logical contradictions and violations of causal consistency. The analysis critically examines major theoretical approaches related to time travel and retrocausality, including closed timelike curves, Novikov’s self-consistency principle, Deutsch’s quantum closed timelike curve model, and the two-state vector formalism in quantum mechanics. The paper argues that while some interpretations may mathematically describe retrocausal correlations, none currently provide an operational mechanism for backward information transmission without encountering paradoxes or information-theoretic inconsistencies. The framework further connects the causal structure of spacetime with the thermodynamic arrow of time, emphasizing the role of entropy, light cone geometry, and information propagation in preserving temporal coherence. The work also explores broader philosophical implications concerning the nature of time, consciousness, causality, and agency within a causally structured universe. Rather than proposing a new physical force or replacing existing theories, this paper provides a logically structured analysis of why temporal observation is compatible with known physics while active temporal intervention remains fundamentally constrained by both physical law and logical consistency.
It has been claimed that quantum mechanics is a non-local theory, i.e., that the predictions of quantum mechanics are at odds with a conception of the world where all the interactions are mediated by local mechanisms. The cited reason is the violation of the Bell inequality in cases where measurements are performed on quantum systems of particles that have interacted in the past. Quantum mechanics predicts that the state of the particles in such a system are correlated, a result obtained from considering a thought-experiment often known as EPR. In this thesis, I will argue that the violation of the Bell inequality in EPR forces us to either accept that causes sometimes act both backwards and forwards in time, or give up some widely-held assumptions about causal relations or the role of causal explanations. First, I will present three principles regarding causality that I take be widely accepted. I will then present the background for the claim the quantum mechanics is a non-local theory, and discuss the implications of non-local causal influences in light of the Special Theory of Relativity. One argument against a causal explanation of the EPR-correlations will be discussed, and different models for the causal structure of EPR will be assessed. I will argue that a retrocausal model – models that include instances of retrocausation, where the direction of causation is the opposite of the direction of time – is the only viable option if we want to uphold the three principles presented in chapter 1. I will discuss the plausibility of rejecting one of these principles, and argue that at least one of the can be restricted in a way that still accounts for our commitment to it. Finally, I will assess the non-local models against the retrocausal models, and argue that a retrocausal model offers interpretational advantages over the non-local alternatives.
This record contains two preprints and their supplementary material, in English and Italian, together with the code and LaTeX sources that reproduce every number and figure. Toward controlled retrocausal communication: the successive-rewriting model and its bottleneck (main paper). Can information be sent to the past? With known physics it cannot; the possibility is not, however, excluded a priori, and the Temporal Radio project asks what would be needed. We show that the bottleneck has a single root: making even a single controllable bit appear in the past without a cause in that past. We show it through the author's successive-rewriting model, formulated with declared premises: a message that reaches the past alters the causal chain, reality is perturbed and resettles, overwriting the future, and a protected log numbers the versions and guides the senders. We formalize it as a dynamics over the versions, in which consistency is not an imposed principle but the equilibrium between settling and the senders' choices; a toy model shows that the author's rule of intervening only for a serious reason allows the succession to stop despite a strong butterfly effect. The bottleneck appears in two forms. The first is the channel: the message must reach the past on a physical signal, which we discuss as a hypothesis in terms of the advanced component of the electromagnetic field; two entangled particles supply a key that only the receiver can use, but reduce neither the amount of information to be sent back nor the difficulty. The second is the persistence of information across versions: with a protected log the model makes a conditional prediction that distinguishes it from Novikov consistency, the alternating entries left by the paradoxical protocol. Future boundary conditions and feedback loops: two solvable models that send no signal to the past (companion note). In models with boundary conditions in the future it is easy to mistake a global dependence for a signal to the past. Two elementary, solvable models make the distinction explicit: two coupled linear oscillators with data at both ends, and a scalar field crossing the throat of an Ellis wormhole placed in a feedback loop. An operational criterion in five conditions organizes what each model does and does not show. The supplementary material contains the catalogue of models, the verification register with the evidence level of every number, and a guide to the computation package. The work was carried out with the assistance of an AI model, as declared in the papers.
*Special Relativity places severe constraints on any possibility for faster-than-light (FTL) phenomenon. There are four hopes for FTL; warp drive via General Relativity Theory (GRT), wormholes via GRT, tachyons, and quantum mechanics. This talk focuses on why quantum mechanics makes the list. The nonlocal nature of matter demonstrates correlations between distant events that cannot be explained by current concepts of causality. For two classical events to be correlated, either one causes the other, or both possess a common cause in their past light cones. Neither kind of causality can explain the correlations observed in entangled quantum systems. Reality seems to support a third mysterious type of causality, with an essential spacelike nature, but direct spacelike causality should be impossible as it would lead to temporal paradox. The two concepts of classical causality, timelike causes and common cause, are presented along with a review of the EPR experiment showing that something like spacelike causality exists between the distant parts of an entangled quantum system. Bell’s Inequality shows that the EPR correlations cannot be attributed to common causes. Gisin’s EPR-Relativity experiment shows that timelike causes cannot explain the EPR correlations either. The metaphor of Quantum Tic-Tac-Toe is used to show a third type of causality applicable only to quantum situations. This third type of causality is an indirect spacelike cause acting through multiple classical realities, permitting FTL but prohibiting temporal paradox. I. Introduction HIS paper considers the issue of causality in entangled quantum systems. The Background section reviews the two classical notions of causality, EPR type entanglements, and Special Relativity. The Common Cause section reviews Bell’s Inequality theorem and shows how this type of causality cannot explain the correlations seen in entangled systems. The Einsteinian Causality section reviews Gisin’s experiment demonstrating that time-like causality cannot explain these correlations either. Gisin’s conclusion is that quantum systems support a new mysterious 3 rd type of causality. The Quantum Causality section introduces a situation in Quantum Tic-Tac-Toe that exhibits this same kind of causality