This paper suggests that time travelling scenarios commonly depicted in science fiction introduce problems and dangers for the time traveller. If time travel takes time, then time travellers risk collision with past objects, relocation to distant parts of the universe, and time travel-specific injuries. I propose several models of time travel that avoid the dangers and risks of time travel taking time, and that introduce new questions about (...) the relationship between time travel and spatial location. (shrink)

Newton supported the idea of absolute time, unlike Leibniz, for which time is only a relation between events and cannot be expressed independently, a statement in concordance with the relativity of space-time. Eternalism claims that the past and the future exist in a real sense, going to the idea that time is a dimension similar to spatial dimensions, that future and past events are "present" on the axis of time, but this view is challenged. (...) On four-dimensional vision, the universe is an existing space-time topology, containing everything that has happened, everything that happens and everything that's going to happen. It follows that there is no singular moment to be considered as insignificant as present. Time travel is possible if the four-dimensional vision including the time is correct, but it is not possible if presentism is true. William Godfrey-Smith says that "the metaphysical image underlying the discussion of time travel is that of the universe block, in which the world is conceived as extended in time as it is in space." DOI: 10.13140/RG.2.2.18575.64163. (shrink)

This paper argues for the following disjunction: either we do not live in a world with a branching temporal structure, or backwards time travel is nomologically impossible, given the initial state of the universe, or backwards time travel to our space-time location is impossible given large-scale facts about space and time. A fortiori, if backwards time travel to our location is possible, we do not live in a branching universe.

Thinking about time travel is an entertaining way to explore how to understand time and its location in the broad conceptual landscape that includes causation, fate, action, possibility, experience, and reality. It is uncontroversial that time travel towards the future exists, and time travel to the past is generally recognized as permitted by Einstein’s general theory of relativity, though no one knows yet whether nature truly allows it. Coherent time travel stories (...) have added flair to traditional debates over the metaphysical status of the past, the reality of temporal passage, and the existence of free will. Moreover, plausible models of time travel and time machines can be used to investigate the subtle relation between space-time structure and causality. -/- It surveys some philosophical issues concerning time travel and should serves as a quick introduction. It includes a new and improved way to define a time machine. (shrink)

I criticize Lockwood’s solution to the “paradoxes” of time travel, thus endorsing Lewis’s more conservative position. Lockwood argues that only in the context of a 5D space-time-actuality manifold is the possibility of time travel compatible with the Autonomy Principle (according to which global constraints cannot override what is physically possible locally). I argue that shifting from 4D space-time to 5D space-time-actuality does not change the situation with respect to the Autonomy (...) Principle, since the shift does not allow us to have a coincidence-free local dynamical theory. (shrink)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially (...) adverbialised properties presents some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially (...) adverbialised properties presents some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

The new understanding of basic dimensions Absolute Time and Space will open the possibility of exploring beyond our current known Universe. These absolute dimensions might supersede our current Spacetime dimension and related theories. Interpretations based on these dimensions could effectively bridge the gap between theories of microscopic and telescopic worlds and it will eventually give us a better picture of our Universe. This book will take us one step closer towards the understanding of our Entire Existence. As we (...) can see below mentioned are some of the current research related topics in the field of Metaphysics and Cosmology. This book will address all these questions and related subsequent questions of this subject. 1. How our universe came into existence? 2. What was the time before the start of the universe? 3. Is there anything outside of this universe? 4. Is time travel possible? 5. Is there any multiverse or parallel universe? (shrink)

Smells seem to offer a great opportunity to restructure the reality of the individual. Yet, the olfactory dimension is rarely part of design strategies in architecture, urban planning or landscape urbanism. As designers, we learn to compose mainly with shapes, shapes whose full scale and effects on our senses we will experience only when constructed. However, we should be primarily concerned with creating spaces that not only open the imagination of the individual but also allow positive moods to thrive. In (...) this scheme, all the senses should be called, not just our vision, as is too often the case. The fields of architecture and environmental design must evolve and train professionals capable of conceptualizing both tangible and intangible forms. In this logic, architectural structures offer a way to call upon our own mindscapes; and within the discipline of design a new field of specialization exists: smellscaping. (shrink)

The topic is time travel of the sort depicted in H. G. Wells’ classic novel, The Time Machine—Wellsian time travel. The range of proper applicability of the concept of Wellsian time travel is investigated. The results of this investigation are applied to provide a new argument against the metaphysical possibility of time travel in absolute time. Alternatively, the argument is against the possibility of Wellsian time travel relative to (...) a single temporal frame of reference. The argument leaves open the prospect that an object nontrivially moves relative to one temporal reference frame from one time to another relative to another temporal reference frame. The argument does not turn on closed timelike curves or “causal loops” of any kind. It does however invoke the prospect of backward causation—a consequence of backward time travel in conjunction with common sense—but it invokes this possibility only in the weak sense of mere logical consistency. (shrink)

In "Changing the Past" (2010), Peter van Inwagen argues that a time traveler can change the past without paradox in a growing block universe. After erasing the portion of past existence that generates paradox, a new, non-paradox-generating block can be "grown" after the temporal relocation of the time traveler. -/- I articulate and explore the underlying mechanism of Van Inwagen's model: the time traveler's control over the location of the objective present. Van Inwagen's model is aimed at (...) preventing paradox by changing the past, but it achieves something broader than paradox avoidance: it gives tools for a new model of time travel. I use van Inwagen's tools to develop a new kind of time travel in which in which the location of the objective present is shifted by the time traveler. I call this type of time travel Movable Objective Present, or MOP. After defining MOP, I argue that it is compatible with any theory of time that accepts hypertime, including presentism and moving spotlight theory. (shrink)

While many aspects of cognition have been shown to be shared between humans and non-human animals, there remains controversy regarding whether the capacity to mentally time travel is a uniquely human one. In this paper, we argue that there are four ways of representing when some event happened: four kinds of temporal representation. Distinguishing these four kinds of temporal representation has five benefits. First, it puts us in a position to determine the particular benefits these distinct temporal representations (...) afford an organism. Second, it provides the conceptual resources to foster a discussion about which of these representations is necessary for an organism to count as having the capacity to mentally time travel. Third, it enables us to distinguish stricter from more liberal views of mental time travel that differ regarding which kind(s) of temporal representation is taken to be necessary for mental time travel. Fourth, it allows us to determine the benefits of taking a stricter or more liberal view of mental time travel. Finally, it ensures that disagreement about whether some species can mentally time travel is not merely the product of unrecognised disagreement about which temporal representation is necessary for mental time travel. We argue for a more liberal view, on the grounds that it allows us to view mental time travel as an evolutionarily continuous phenomenon, and to recognise that differences in the ways that organisms mentally time travel might reflect different temporal representations, or combinations thereof, that they employ. Our ultimate aim, however, is to create the conceptual framework for further discussion regarding what sorts of temporal representations are required for mental time travel. (shrink)

This book is my gift to Albert Einstein on the occasion of his 142nd birthday - and is also a gift to everybody in the world he helped to shape! -/- My book adopts the view that the universe is infinite and eternal - but scientifically created. This paradox of creating eternity depends on the advanced electronics developed by future humanity. Those humans will develop time travel, plus programs that use "imaginary" time and infinite numbers like pi. (...) They'll also become the El or Elohim (names used by various religions to mean "God" or "the gods"). As astronomer Carl Sagan wrote in "Pale Blue Dot", "Many religions teach that it is the goal of humans to become gods." (I think that Elohim would be termed supernatural today, though their infinite abilities are actually natural outcomes of progress.) -/- A look through the book will tell you that some ideas are frequently repeated. This is because each article is meant to be understood without reading the others … so the same ideas show up in more than one. I’ve tried to stay away from jargon and equations unless they’re necessary (I find that they often make a subject harder to understand, not easier). All objects and events on Earth, in space, and in time (including the inevitability of world peace and immortality) are just one thing – strings of electronics' binary digits 1 and 0. -/- -/- TABLE OF CONTENTS -/- CHAPTER 1 - HYPOTHESIS OF QUANTUM GRAVITY -/- CHAPTER 2 - THE PHYSICIST AND THE PHILOSOPHER -/- CHAPTER 3 - ATTENTION MEDICAL DOCTORS! PHYSICS THEORY IMPLIES ALL PATIENTS CAN BE NORMALISED USING GRAVITY -/- CHAPTER 4 - SETI, EVOLUTION, AND TIME -/- CHAPTER 5 - ANYONS - ONE KEY TO UNLOCK GRAVITATIONAL-ELECTROMAGNETIC UNION, THE TOPOLOGICAL UNIVERSE, SPACE-TIME TRAVEL, FUTURE COMPUTERS, DARK MATTER/DARK ENERGY -/- CHAPTER 6 - WHAT CAUSES THE PLANETS TO SPEED UP AND SLOW DOWN WHILE THEY ARE ORBITING THE SUN -/- CHAPTER 7 - A BRIEF OUTLINE OF THE POSSIBLE BASICS OF COSMOLOGY IN THE 22nd CENTURY, AND WHAT IT MEANS FOR RELIGION -/- CHAPTER 8 - THE WORLD'S REAL-LIFE EXPERIMENTS WITH COVID-19 AND PHYSICS ALTER SOCIETY AND GLOBAL ECONOMICS -/- CHAPTER 9 - UNITING TIME -/- CHAPTER 10 - EXTRACTING ENERGY FROM BLACK HOLES -/- CHAPTER 11 - TIME TREK: THE 25TH CENTURY'S ANSWER TO STAR TREK. (shrink)

This paper is a brief (and hopelessly incomplete) non-standard introduction to the philosophy of space and time. It is an introduction because I plan to give an overview of what I consider some of the main questions about space and time: Is space a substance over and above matter? How many dimensions does it have? Is space-time fundamental or emergent? Does time have a direction? Does time even exist? Nonetheless, this introduction (...) is not standard because I conclude the discussion by presenting the material with an original spin, guided by a particular understanding of fundamental physical theories, the so-called primitive ontology approach. (shrink)

This paper is an enquiry into the logical, metaphysical, and physical possibility of time travel understood in the sense of the existence of closed worldlines that can be traced out by physical objects. We argue that none of the purported paradoxes rule out time travel either on grounds of logic or metaphysics. More relevantly, modern spacetime theories such as general relativity seem to permit models that feature closed worldlines. We discuss, in the context of Gödel's infamous (...) argument for the ideality of time based on his eponymous spacetime, what this apparent physical possibility of time travel means. Furthermore, we review the recent literature on so-called time machines, i.e., of devices that produce closed worldlines where none would have existed otherwise. Finally, we investigate what the implications of the quantum behaviour of matter for the possibility of time travel might be and explicate in what sense time travel might be possible according to leading contenders for full quantum theories of gravity such as string theory and loop quantum gravity. (shrink)

This article argues that existing approaches to programming ethical AI fail to resolve a serious moral-semantic trilemma, generating interpretations of ethical requirements that are either too semantically strict, too semantically flexible, or overly unpredictable. This paper then illustrates the trilemma utilizing a recently proposed ‘general ethical dilemma analyzer,’ GenEth. Finally, it uses empirical evidence to argue that human beings resolve the semantic trilemma using general cognitive and motivational processes involving ‘mental time-travel,’ whereby we simulate different possible pasts and (...) futures. I demonstrate how mental time-travel psychology leads us to resolve the semantic trilemma through a six-step process of interpersonal negotiation and renegotiation, and then conclude by showing how comparative advantages in processing power would plausibly cause AI to use similar processes to solve the semantic trilemma more reliably than we do, leading AI to make better moral-semantic choices than humans do by our very own lights. (shrink)

In this paper, I argue that the thesis that time travel is logically possible, is inconsistent with the necessary truth of any of the usual ‘open futureobjective present’ models of the universe. It has been relatively uncontroversial until recently to hold that presentism is inconsistent with the possibility of time travel. I argue that recent arguments to the contrary do not show that presentism is consistent with time travel. Moreover, the necessary truth of other (...) open future-objective present models which we might, prima facie, have supposed to be more amenable to the possibility of time travel, turn out also to be inconsistent with this possibility. (shrink)

Kadri Vihvelin, in "What time travelers cannot do" (Philos Stud 81: 315-330, 1996), argued that "no time traveler can kill the baby who in fact is her younger self, because (V1) "if someone would fail to do something, no matter how hard or how many times she tried, then she cannot do it", and (V2) if a time traveler tried to kill her baby self, she would always fail. Theodore Sider (Philos Stud 110: 115-138, 2002) criticized Vihvelin's (...) argument, and Ira Kiourti (Philos Stud 139: 343-352, 2008) criticized both Vihvelin's argument and Sider's critique. I present a critique of Vihvelin's argument different from both Sider's and Kiourti's critiques: I argue in a novel way that both V1 and V2 are false. Since Vihvelin's argument might be understood as providing a challenge to the possibility of time travel, if my critique succeeds then time travel survives such a challenge unscathed. (shrink)

The Principle of Alternative Possibilities is the intuitive idea that someone is morally responsible for an action only if she could have done otherwise. Harry Frankfurt has famously presented putative counterexamples to this intuitive principle. In this paper, I formulate a simple version of the Principle of Alternative Possibilities that invokes a course-grained notion of actions. After warming up with a Frankfurt-Style Counterexample to this principle, I introduce a new kind of counterexample based on the possibility of time (...) class='Hi'>travel. At the end of the paper, I formulate a more sophisticated version of the Principle of Alternative Possibilities that invokes a certain fine grained notion of actions. I then explain how this new kind of counterexample can be augmented to show that even the more sophisticated principle is false. (shrink)

Future-biased individuals systematically prefer positively valenced events to be in the future (positive future-bias) and negatively valenced events to be in the past (negative future-bias). The most extreme form of future-bias is absolute future-bias, whereby we completely discount the value of past events when forming our preferences. Various authors have thought that we are absolutely future-biased (Sullivan (2018:58); Parfit (1984:173) and that future-bias (absolute or otherwise) is at least rationally permissible (Prior (1959), Hare (2007; 2008), Kauppinen (2018), Heathwood (2008)). The (...) permissibility of future-bias is often held to be grounded in the structure of the temporal dimension. In this paper I consider several proposals for grounding the permissibility of such preferences and evaluate these in the light of the preferences we would have, and judge that we should have, in various time-travel scenarios. I argue that what we learn by considering these scenarios is that these preferences really have nothing to do with temporal structure. So if something grounds their permissibility, it is not temporal structure. (shrink)

The goal of this paper is to defend the general tenet that time travelers cannot change the past within B-theoretical models of time, independently of how many temporal dimensions there are. Baron Pacific Philosophical Quarterly, 98, 129–147 offered a strong argument intended to reach this general conclusion. However, his argument does not cover a peculiar case, i.e. a B-theoretical one-dimensional model of time that allows for the presence of internal times. Loss Pacific Philosophical Quarterly, 96, 1–11 used (...) the latter model to argue that time travelers can change the past within such model. We show a way to debunk Loss’s argument, so that the general tenet about the impossibility of changing the past within B-theoretical models is maintained. (shrink)

This paper is dedicated to articulating the ethical puzzles that arise from the possibility of time travel. I divide the puzzles into three different categories: permissibility puzzles, obligation puzzles, and conflicts between past and future selves. In each category, I suggest that ethical problems involving time travel are not as dissimilar to parallel “normal” ethical puzzles as one might think.

It has sometimes been suggested that backwards time travel always incurs causal loops. I show that this is mistaken, by describing worlds where backwards time travel occurs and yet no causal loops occur. Arguments that backwards time travel can occur without causal loops have been given before in the literature, but I show that those arguments are unconvincing.

The idea that episodic memory is a form of mental time travel has played an important role in the development of memory research in the last couple decades. Despite its growing importance in psychology, philosophers have only begun to develop an interest in philosophical questions pertaining to the relationship between memory and mental time travel. Thus, this paper proposes a more systematic discussion of the relationship between memory and mental time travel from the point (...) of view of philosophy. I start by discussing some of the motivations to take memory to be a form of mental time travel. I call the resulting view of memory the mental time travel view. I then proceed to consider important philosophical questions pertaining to memory and develop them in the context of the mental time travel view. I conclude by suggesting that the intersection of the philosophy of memory and research on mental time travel not only provides new perspectives to think about traditional philosophical questions, but also new questions that have not been explored before. (shrink)

A recent account of presentist time travel involves a causal relation between events at two different and discontiguous times, and presentists cannot have such causal relations because presentism rules out the existence of at least one of the two relata in such a relation due to it being non-present. Additionally, presentists cannot have parodies of such causal relations for use in time travel stories because parodies are subject, at least, to the same limitations as the things (...) being parodied. So, the presentist has not successfully given an internally consistent account of presentist time travel. (shrink)

In this paper I give consideration to some apparent impossibilities for the time travelers to the past. After criticizing the views of D. Lewis and K. Vihvelin, I will show in what sense they are really impossible.

The first section of this article focuses on the treatment of “time travel” in science-fiction literature and film as presented in the secondary literature in that field. The first anthology I will consider has a metaphysical focus, including (a) relating the time travel of science fiction to the banal time travel of all living beings, as we move inexorably toward the future; and (b) arguing for the filmstrip as the ultimate metaphor for time. (...) The second anthology I will consider has a more political focus, arguing that the “special effects” form of science-fiction films, rather than the visual or narrative content of science-fiction-films, is truly imaginative and futural. The second section of this article ties together a variety of concepts and insights between time-travel cinema and Deleuze’s Cinema 1, suggesting (among other things) that (c) time-traveling characters in cinema function as a redoubled phenomenon of the “mobile sections” of Bergsonian duration (in reference to Henri Bergson), and (d) time-travel cinema vividly illustrates the imagistic nature of the entire world. (shrink)

Episodic memory (memories of the personal past) and prospecting the future (anticipating events) are often described as mental time travel (MTT). While most use this description metaphorically, we argue that episodic memory may allow for MTT in at least some robust sense. While episodic memory experiences may not allow us to literally travel through time, they do afford genuine awareness of past-perceived events. This is in contrast to an alternative view on which episodic memory experiences present (...) past-perceived events as mere intentional contents. Hence, episodic memory is a way of coming into experiential contact with, or being again aware of, what happened in the past. We argue that episodic memory experiences depend on a causal-informational link with the past events being remembered, and that, assuming direct realism about episodic memory experiences, this link suffices for genuine awareness. Since there is no such link in future prospection, a similar argument cannot be used to show that it also affords genuine awareness of future events. Constructivist views of memory might challenge the idea of memory as genuine awareness of remembered events. We explain how our view is consistent with both constructivist and anti-causalist conceptions of memory. There is still room for an interpretation of episodic memory as enabling genuine awareness of past events, even if it involves reconstruction. (shrink)

Notoriously, the Einstein equations of general relativity have solutions in which closed timelike curves occur. On these curves time loops back onto itself, which has exotic consequences: for example, traveling back into one's own past becomes possible. However, in order to make time travel stories consistent constraints have to be satisfied, which prevents seemingly ordinary and plausible processes from occurring. This, and several other "unphysical" features, have motivated many authors to exclude solutions with CTCs from consideration, e.g. (...) by conjecturing a chronology protection law. In this contribution we shall investigate the nature of one particular class of exotic consequences of CTCs, namely those involving unexpected cases of indeterminism or determinism. Indeterminism arises even against the backdrop of the usual deterministic physical theories when CTCs do not cross spacelike hypersurfaces outside of a limited CTC-region|such hypersurfaces fail to be Cauchy surfaces. We shall compare this CTC-indeterminism with four other types of indeterminism that have been discussed in the philosophy of physics literature: quantum indeterminism, the indeterminism of the hole argument, non-uniqueness of solutions of differential equations and lack of predictability due to insuffcient data. By contrast, a certain kind of determinism appears to arise when an indeterministic theory is applied on a CTC: things cannot be different from what they already were. Again we shall make comparisons, this time with other cases of determination in physics. We shall argue that on further consideration both this indeterminism and determinism on CTCs turn out to possess analogues in other, familiar areas of physics. CTC- indeterminism is close to the epistemological indeterminism we know from statistical physics, while the "fixedness" typical of CTC-determinism is pervasive in physics. CTC- determinism and CTC-indeterminism therefore do not provide incontrovertible grounds for rejecting CTCs as conceptually inadmissible. (shrink)

Continuists maintain that, aside from their distinct temporal orientations, episodic memory and future-oriented mental time travel (FMTT) are qualitatively continuous. Discontinuists deny this, arguing that, in addition to their distinct temporal orientations, there are qualitative metaphysical or epistemological differences between episodic memory and FMTT. This chapter defends continuism by responding both to arguments for metaphysical discontinuism, based on alleged discontinuities between episodic memory and FMTT at the causal, intentional, and phenomenological levels, and to arguments for epistemological discontinuism, based (...) on alleged discontinuities with respect to the epistemic openness of the past and future, the directness or indirectness of our knowledge of past and future, and immunity to error through misidentification. The chapter concludes by sketching a positive argument for continuism. (shrink)

By eliminating the need for an absolute frame of reference or ether, Einstein resolved the problem of the constancy of light-speed in all inertial frames but created a new problem in our understanding of time. The resolution of this problem requires no experimentation but only a careful analysis of special relativity, in particular the relativity of simultaneity. This concept is insufficiently relativistic insofar as Einstein failed to recognize that any given set of events privileges the frame in which the (...) events occur; relative to those events, only the privileged frame yields the correct measurement. Instead of equally valid frames occupying different times, one frame is correct and all others incorrect within a shared present moment. I conclude that (1) time is a succession of universal moments and (2) in the context of flowing time, time dilation requires absolute simultaneity, whereas relative simultaneity predicts a nonexistent phenomenon here dubbed time regression. (shrink)

This paper brings two fresh perspectives on Lewis’s theory of time travel. First: many key aspects and theoretical desiderata of Lewis’s theory can be captured in a framework that does not commit to eternalism about time. Second: implementing aspects of Lewisian time travel in a non-eternalist framework provides theoretical resources for a better treatment of time travel to the future. While time travel to the past has been extensively analyzed, time (...) travel to the future has been comparatively underexplored. I make progress on this topic. Along the way, I discuss Lewis’s lesser-known time travel oeuvre, especially his volume of correspondence and lectures on the topic collected in Beebee and Fisher (2020) and Janssen-Lauret & MacBride (forthcoming). Lewis’s body of unpublished work on time travel yields fruitful insights into his broader thinking on the subject. (shrink)

It has been suggested that there is something worrisome, puzzling, or incomprehensible about the sorts of causal loops sometimes involved in backwards time travel. This paper disentangles two distinct puzzles and evaluates whether they provide us reason to find backwards time travel incomprehensible, inexplicable, or otherwise worrisome. The paper argues that they provide no such reason.

This paper explores what the metaphysics of time travel might teach us about moral responsibility. We take our cue from a recent paper by Yishai Cohen, who argues that if time travel is metaphysically possible, then one of the most influential theories of moral responsibility (i.e., Fischer and Ravizza’s) is false. We argue that Cohen’s argument is unsound but that Cohen’s argument can serve as a lens to bring reasons-responsive theories of moral responsibility into sharper focus, (...) helping us to better understand actual-sequence theories of moral responsibility more generally and showing how actual-sequence theorists should respond to a recent criticism. (shrink)

In this chapter I articulate the threat that time travel to the past allegedly poses to the free will of the time traveler, and I argue that on the traditional way of thinking about free will, the incompatibilist about time travel and free will wins the day. However, a residual worry about the incompatibilist view points the way toward a novel way of thinking about free will, one that I tentatively explore toward the end of (...) the chapter. (shrink)

Bringing research on collective memory together with research on episodic future thought, Szpunar and Szpunar :376–389, 2016) have recently developed the concept of collective future thought. Individual memory and individual future thought are increasingly seen as two forms of individual mental time travel, and it is natural to see collective memory and collective future thought as forms of collective mental time travel. But how seriously should the notion of collective mental time travel be taken? (...) This article argues that, while collective mental time travel is disanalogous in important respects to individual mental time travel, the concept of collective mental time travel nevertheless provides a useful means of organizing existing findings, while also suggesting promising directions for future research. (shrink)

Time travel is a recognized concept in philosophy and science, but whose scope is highly disputed, giving rise to numerous paradoxes in both philosophy and science. Time travel is considered by some accepted both in general relativity and quantum mechanics, but there is a unanimous consensus that it is not feasible with current technology. (Hawkins 2010) The raised issues are different for the time travel in the past compared to the time travel (...) in the future. (shrink)

I distinguish paradoxes and hypodoxes among the conundrums of time travel. I introduce ‘hypodoxes’ as a term for seemingly consistent conundrums that seem to be related to various paradoxes, as the Truth-teller is related to the Liar. In this article, I briefly compare paradoxes and hypodoxes of time travel with Liar paradoxes and Truth-teller hypodoxes. I also discuss Lewis’ treatment of time travel paradoxes, which I characterise as a Laissez Faire theory of time (...) travel. Time travel paradoxes are impossible according to Laissez Faire theories, while it seems hypodoxes are possible. (shrink)

Spatial models dominated memory research throughout much of the 20th century, but in recent decades, the concept of memory as a form of mental time travel (MTT) to the past has gained prominence. Initially introduced as a metaphor, the MTT perspective shifted the focus from internal memory processes to the subjective conscious experience of remembering. Despite its significant impact on empirical and theoretical memory research, there has been limited discussion regarding the meaning and adequacy of the MTT metaphor (...) in accounting for memory. While previous work has addressed the general limitations of the MTT metaphor in explaining memory (Trakas, 2022), the objective of this article is more focused and modest: to gain a better understanding of what constitutes MTT to the past. To achieve this objective, a detailed analysis of the characteristics of MTT to the past is presented through a comparison with time travel (TT) to the past. Although acknowledging that TT does not refer to an existing physical phenomenon, it is an older concept extensively discussed in the philosophical literature and provides commonly accepted grounds, particularly within orthodox theories of time, that can offer insights into the nature of MTT. Six specific characteristics serve as points of comparison: (1) a destination distinct from the present, (2) the distinction between subjective time and objective time, (3) the subjective experience of the time traveler, (4) their differentiation from the past self, (5) the existence of the past, and (6) its unchangeability. Through this research, a detailed exploration of the phenomenal and metaphysical aspects of MTT to the past is undertaken, shedding light on the distinct features that mental time travel to the past acquires when it occurs within the realm of the mind rather than as a physical phenomenon. By examining these characteristics, a deeper understanding of the nature of mental time travel is achieved, offering insights into how it operates in relation to memory and the past. (shrink)

Ganeri's [2018] discussion of mental time travel and the self focuses on remembering the past, but has less to say with respect to the status of future-oriented mental time travel. This paper aims to disambiguate the relation between prospection and the self from the framework of Ganeri's interpretation of three Buddhist views—by Buddhaghosa, Vasubandhu, and Dignaga. Is the scope of Ganeri's discussion confined to the past, or is there a stronger assumption that future thought always entails (...) self-representation? I argue that if mental time travel towards the past and towards the future are continuous, both past and future thought should be possible independently of self-representation. An assumption of discontinuity however would enable the employment of the self as one of the defining differences between remembering the past and imagining the future. The two options can be further contrasted on the basis of distinct ways of constructing past/future scenarios (field vs. observer perspective), modes of experiencing time (known vs. lived), and the origin of mental time travel (episodic vs. semantic memory). I further assess the compatibility of future-oriented thought with the three Buddhist views on the basis of these coordinates. (shrink)

The question of time travel stimulates the imagination and provides material for whimsical stories. A work on the topic of "time travel" forces us to deal with the concept of "time". The complexity and the antinomic character of this concept make it difficult to grasp "time" more precisely. We encounter time as a form of perception in its deeply subjective aspect, as a biological rhythm, as a social phenomenon in the sense of a (...) collective determination of time, but also as a physical quantity. Einstein's theory of relativity revolutionized our ideas of space and time. His Special Theory of Relativity (1905) allows "travel into the future" through the effect of time dilation he predicted, and Einstein's theory of gravity allows for closed time lines as solutions to its equations (e.g., Gödel cosmos, anti-de Sitter cosmos). However, traveling in a time loop would immediately lead to a number of paradoxes (e.g., grandfather paradox, information paradox). Although, surprisingly, the basic laws of physics (apart from extremely rare and macroscopically non-appearing quantum mechanical effects) would not be violated in a time reversal, there seems to be a fundamental prohibition of traveling into the past in nature. (shrink)

This paper argues that all of the standard theories about the divisions of space and time can benefit from, and may need to rely on, parsimony considerations. More specifically, whether spacetime is discrete, gunky or pointy, there are wildly unparsimonious rivals to standard accounts that need to be resisted by proponents of those accounts, and only parsimony considerations offer a natural way of doing that resisting. Furthermore, quantitative parsimony considerations appear to be needed in many of these cases.

Modern cosmology treats space and time, or rather space-time, as concrete particulars. The General Theory of Relativity combines the distribution of matter and energy with the curvature of space-time. Here space-time appears as a concrete entity which affects matter and energy and is affected by the things in it. I question the idea that space-time is a concrete existing entity which both substantivalism and reductive relationism maintain. Instead I propose an (...) alternative view, which may be called non-reductive relationism, by arguing that space and time are abstract entities based on extension and changes. (shrink)

Outlined here is a simulation hypothesis approach that uses an expanding (the simulation clock-rate measured in units of Planck time) 4-axis hyper-sphere and mathematical particles that oscillate between an electric wave-state and a mass (unit of Planck mass per unit of Planck time) point-state. Particles are assigned a spin axis which determines the direction in which they are pulled by this (hyper-sphere pilot wave) expansion, thus all particles travel at, and only at, the velocity of expansion (the (...) origin of $c$), however only the particle point-state has definable co-ordinates within the hyper-sphere. Photons are the mechanism of information exchange, as they lack a mass state they can only travel laterally (in hypersphere co-ordinate terms) between particles and so this hypersphere expansion cannot be directly observed, relativity then becomes the mathematics of perspective translating between the absolute (hypersphere) and the relative motion (3D space) co-ordinate systems. A discrete `pixel' lattice geometry is assigned as the gravitational space. Units of $\hbar c$ `physically' link particles into orbital pairs. As these are direct particle to particle links, a gravitational force between macro objects is not required, the gravitational orbit as the sum of these individual orbiting pairs. A 14.6 billion year old hyper-sphere (the sum of Planck black-hole units) has similar parameters to the cosmic microwave background. The Casimir force is a measure of the background radiation density. (shrink)

A perverted space-time geodesy results from the idea of variable rods and clocks, whose length and rates are taken to be affected by the gravitational field. By contrast, what we might call a concrete geodesy relies on the idea of invariable unit-measuring rods and clocks. Indeed, this is a basic assumption of general relativity. Variable rods and clocks lead to a perverted geodesy, in the sense that a curved space-time may be seen as a result of (...) a departure from the Minkowskian space-time as an effect of the gravitational field on the rate of clocks and the length of rods. In the case of a concrete geodesy, we have a curved space-time “directly”, the curvature of which can be determined using (invariable) unit-measuring rods and clocks. In this paper, we will make the case for the plausibility of the claim that Einstein’s views on geometry in relation to general relativity are permeated by a perverted geodesy. (shrink)

The article fits into the debate regarding space, time and nature in dialogue with the world lived by subjects that build up themselves or are built as mythological heroes, source of speech and spacial concrete practices. It's a poorly explored field in Geography that recently approaches to the cultural dynamic debate, to the symbolic field and also to their spacialization processes. The aim is to discuss the possibility of understanding in the present time about the space (...) organization processes related to the society's previous moments, in a space/time dialectics which articulate the present and past times in a complex and non linear way. Methodologically, starting from a literature review about the theme, the present study was linked to the field and documental research about migration to the vicinal ways of Transamazônica Highway (BR-230 Highway), the creation of the "Centro Espírita União do Vegetal", a religion that arises in the Amazon and set up its headquarters in Brasília and the construction of Brasilia as a modern metropolis without a past. The conclusion points at the possibility of space/time nexuses linking the Myth of Nature to the Creation of Heroes, constantly appropriated and with new meanings, in order to support speeches and new actions dialectically throughout the Brazilian contemporaneous space. (shrink)

The question of time travel stimulates the imagination and provides material for whimsical stories. A work on the topic of "time travel" forces us to deal with the concept of "time". The complexity and the antinomic character of this concept make it difficult to grasp "time" more precisely. We encounter time as a form of perception in its deeply subjective aspect, as a biological rhythm, as a social phenomenon in the sense of a (...) collective determination of time, but also as a physical quantity. Einstein's theory of relativity revolutionized our ideas of space and time. His Special Theory of Relativity (1905) allows "travel into the future" through the effect of time dilation he predicted, and Einstein's theory of gravity allows for closed time lines as solutions to its equations (e.g., Gödel cosmos, anti-de Sitter cosmos). However, traveling in a time loop would immediately lead to a number of paradoxes (e.g., grandfather paradox, information paradox). Although, surprisingly, the basic laws of physics (apart from extremely rare and macroscopically non-appearing quantum mechanical effects) would not be violated in a time reversal, there seems to be a fundamental prohibition of traveling into the past in nature. (shrink)

Space-time intervals are the fundamental components of conscious experience, gravity, and a Theory of Everything. Space-time intervals are relationships that arise naturally between events. They have a general covariance (independence of coordinate systems, scale invariance), a physical constancy, that encompasses all frames of reference. There are three basic types of space-time intervals (light-like, time-like, space-like) which interact to create space-time and its properties. Human conscious experience is a four-dimensional space- (...) class='Hi'>time continuum created through the processing of space-time intervals by the brain; space-time intervals are the source of conscious experience (observed physical reality). Human conscious experience is modeled by Einstein’s special theory of relativity, a theory designed specifically from the general covariance of space-time intervals (for inertial frames of reference). General relativity is our most accurate description of gravity. In general relativity, the general covariance of space-time intervals is extended to all frames of reference (inertial and non-inertial), including gravitational reference frames; space-time intervals are the source of gravity in general relativity. The general covariance of space-time intervals is further extended to quantum mechanics; space-time intervals are the source of quantum gravity. The general covariance of space-time intervals seamlessly merges general relativity with quantum field theory (the two grand theories of the universe). Space-time intervals consequently are the basis of a Theory of Everything (a single all-encompassing coherent theoretical framework of physics that fully explains and links together all physical aspects of the universe). This theoretical framework encompasses our observed physical reality (conscious experience) as well; space-time intervals link observed physical reality to actual physical reality. This provides an accurate and reliable match between observed physical reality and the physical universe by which we can carry on our activity. The Minkowski metric, which defines generally covariant space-time intervals, may be considered an axiom (premise, postulate) for the Theory of Everything. (shrink)