Physics of Time

On one popular view, the general covariance of gravity implies that change is relational in a strong sense, such that all it is for a physical degree of freedom to change is for it to vary with regard to a second physical degree of freedom. At a quantum level, this view of change as relative variation leads to a fundamentally timeless formalism for quantum gravity. Here, we will show how one may avoid this acute ‘problem of time’. Under our view, (...) duration is still regarded as relative, but temporal succession is taken to be absolute. Following our approach, which is presented in more formal terms in, it is possible to conceive of a genuinely dynamical theory of quantum gravity within which time, in a substantive sense, remains. 1 Introduction1.1 The problem of time1.2 Our solution2 Understanding Symmetry2.1 Mechanics and representation2.2 Freedom by degrees2.3 Voluntary redundancy3 Understanding Time3.1 Change and order3.2 Quantization and succession4 Time and Gravitation4.1 The two faces of classical gravity4.2 Retaining succession in quantum gravity5 Discussion5.1 Related arguments5.2 Concluding remarks. (shrink)

Presentists have typically argued that the Block View is incapable of explaining our experience of time. In this paper I argue that the phenomenology of our experience of time is, on the contrary, against presentism. My argument is based on a dilemma: presentists must either assume that the metaphysical present has no temporal extension, or that it is temporally extended. The former horn leads to phenomenological problems. The latter renders presentism metaphysically incoherent, unless one posits a discrete present that, however, (...) suffers from the same difficulties that the instantaneous present is prone to. After introducing the main phenomenological models of our experience of time that are discussed in the literature, I show that none of them favors presentism. I conclude by arguing that if even the phenomenology of time sides against presentism, the latter metaphysical theory has no scientific evidence in its favor and ought to be dropped. (shrink)

We consider time as a fuzzy concept. Based on this, the Fuzzy Time-Particle interpretation Of Quantum Mechanics is introduced as an interpretation of Quantum Mechanics [4],[5],[6]. Here, we show how to compute the function associated to Fuzzy time.

This note briefly discusses the observation of elapsed time in a flat universe while exploring the argument of past-eternal time versus emergent time in cosmology. A flat universe with an incomplete past forever has a finite age. Despite an infinite number of Planck time coordinates independent of phenomena and endless expansion, a flat universe never develops an age with an infinite number of Planck times. This observation indicates the impossibility of infinitely elapsed time in the future or past, which limits (...) acceptable scientific models of cosmology. (shrink)

In this chapter, we see one way that time flow may force us to develop our physical theory if we add it back into physics proper. Now of course this is speculative in this context, and should be thought of as a model. The two following extracts are from introductions a more complete unified theory. They explain the basic mathematical models that are required to illustrate the point that such models may be plausible. The second extract, ‘the parable of the (...) ants’, introduces us to the ideological-philosophical conflict that prevents such a development being considered in the present generation, which we will go on to next. (shrink)

This chapter starts with a simple conventional presentation of time reversal in physics, and then returns to analyse it, rejects the conventional analysis, and establishes correct principles in their place.

The conventional claims and concepts of 5* - 8* are a hang-over from the classical theory of thermodynamics – i.e. thermodynamics based on a fully deterministic micro-theory, developed in the time of Boltzmann, Loschmidt and Gibbs in the late C19th. The classical theory has well-known ‘reversibility paradoxes’ when applied to the universe as a whole. But the introduction of intrinsic probabilities in quantum mechanics, and its consequent time asymmetry, fundamentally changes the picture.

A number of general theories of physics provide a model for the fundamental rules that govern our universe, becoming a structural framework to which the new discoveries must conform. The theory of relativity is such a general theory. The theory of relativity is a complex theoretical framework that facilitates the understanding of the universal laws of physics. It is based on the curved space-time continuum fabric abstract concept, and it is well suited for interpreting cosmic events. More so, a general (...) theory based on abstract concepts and imagination facilitates the emergence of countless new extravagant theories. A new simplified theory of the natural world is necessary, a simple theory that provides a verifiable framework on which new discoveries can be integrated. The paper describes a view of the abstract time/space concept, and also a very simple model of our ever-changing universe. Views of physicists, mathematicians, chemists, engineers and of course philosophers have to be all in harmony with such a theory. We leave in a beautiful, uniform, and logical world. We live in a world where everything probable is possible. Contact email: [email protected] . (shrink)

The Simulation Hypothesis proposes that all of reality is in fact an artificial simulation, analogous to a computer simulation. Outlined here is a method for programming relativistic mass, space and time at the Planck level as applicable for use in Planck Universe-as-a-Simulation Hypothesis. For the virtual universe the model uses a 4-axis hyper-sphere that expands in incremental steps (the simulation clock-rate). Virtual particles that oscillate between an electric wave-state and a mass point-state are mapped within this hyper-sphere, the oscillation driven (...) by this expansion. Particles are assigned an N-S axis which determines the direction in which they are pulled along by the expansion, thus an independent particle motion may be dispensed with. Only in the mass point-state do particles have fixed hyper-sphere co-ordinates. The rate of expansion translates to the speed of light and so in terms of the hyper-sphere co-ordinates all particles (and objects) travel at the speed of light, time (as the clock-rate) and velocity (as the rate of expansion) are therefore constant, however photons, as the means of information exchange, are restricted to lateral movement across the hyper-sphere thus giving the appearance of a 3-D space. Lorentz formulas are used to translate between this 3-D space and the hyper-sphere co-ordinates, relativity resembling the mathematics of perspective. (shrink)

Following the 26th General Conference on Weights and Measures are fixed the numerical values of the 4 physical constants ($h, c, e, k_B$). This is premised on the independence of these constants. This article discusses a model of a mathematical electron from which can be defined the Planck units as geometrical objects (mass M=1, time T=2$\pi$ ...). In this model these objects are interrelated via this electron geometry such that once we have assigned values to 2 Planck units then we (...) have fixed the values for all Planck units. As all constants can then be defined using geometrical forms (in terms of 2 fixed mathematical constants, 2 unit-specific scalars and a defined relationship between the units $kg, m, s, A$), the least precise CODATA 2014 constants ($G, h, e, m_e, k_B$...) can then be solved via the most precise ($c, \mu_0, \alpha, R_\infty$), with numerical precision limited by the precision of the fine structure constant $\alpha$. In terms of this model we now for example have 2 separate values for elementary charge, calculated from ($c, \alpha, R_\infty$) and the 2017 revision. (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)

The purpose of this yet-another version of this note is to make another attempt to show how an 'AB-series' interpretation of time, given in a companion paper, leads, surprisingly, apparently, to the signature of the physicists' important AdS^5 geometry. This is not a theory of 2 time dimensions. Rather, it is a theory of 1 time dimension that has both A-series and B-series characteristics.

This paper proposes an interpretation of time that incorporates both McTaggart's A-series and his B-series, and attempts to cast it in a way that might be usable by physicists. This interpretation allows one to reconcile special relativity with temporal becoming as the latter is understood as 'ontologically private', which is given a mathematical definition. This allows one to define a unit of becoming, as well as the rates of becoming. This paper gives a picture of this interpretation and applies a (...) rough outline of the concepts to several test cases. (shrink)

This paper proposes an interpretation of time that is an 'A-theory' in that it incorporates both McTaggart's A-series and his B-series. The A-series characteristics are supposed to be 'ontologically private' analogous to qualia in the Inverted Spectrum thought experiment and is given a definition. It is proposed one may define a 'unit of becoming' that coordinatizes the future/present/past spectrum as well as allowing one to calculate the rates of becoming. We give a picture of this interpretation and discuss how it (...) relates to the Schrodinger's Cat paradox. (shrink)

This paper proposes an interpretation of time that is an 'A-theory' in that it incorporates both McTaggart's A-series and his B-series. The A-series characteristics are supposed to be 'ontologically private' analogous to qualia in the Inverted Spectrum thought experiment and is given a definition. The main idea is that the experimenter and the cat do not share the same A-series characteristics. So there is no single time at which the cat gets ascribed different states. It is proposed one may define (...) a 'unit of becoming' that coordinatizes the future/present/past spectrum as well as allowing one to calculate the rates of becoming. We give a picture of this interpretation and discuss how it relates to the Schrodinger's Cat 'paradox'. Also relativity is briefly considered. (shrink)

A theory of time was proposed in "A theory of time", an early version of which is on PhilPapers. The idea was that the A-series features of a physical system are ontologically private, and this was given a mathematical definition. Also B-series features are ontologically public. This brief note is a detailed rumination on path-integrals and Schrodinger's Cat, in this theory.

The purpose of this note is to show how an 'AB-series' interpretation of time, given in a companion paper, leads, surprisingly, to AdS_5 geometry. This is not a theory of 2 time dimensions. Rather, it is a theory of 1 time dimension that has both A-series and B-series characteristics.

The purpose of this note is to show how an 'AB-series' interpretation of time leads, surprisingly, apparently, to AdS_5 geometry. This is not a theory of 2 time dimensions. Rather, it is a theory of 1 time dimension that has both A-series and B-series characteristics. To summarize the result, a spacetime in terms of (1) the earlier-to-later aspect of time, and (2) the (related) future-present-past aspect of time, and (3) 3-d space, it would seem, gives us the AdS_5 geometry.

The mathematical constructions, physical structure and manifestations of physical time are reviewed. The nature of insight and mathematics used to understand and deal with physical time associated with classical, quantum and cosmic processes is contemplated together with a comprehensive understanding of classical time. Scalar time (explicit time or quantitative time), vector time (implicit time or qualitative time), biological time, time of and in conscious awareness are discussed. The mathematical understanding of time in special and general theories of relativity is critically (...) analyzed. The independent nature of classical, quantum and cosmic physical times from one another, and the manifestations of respective physical happenings, distinct from universal time, are highlighted. The role of a universal time related or unrelated to origin, being etc., of universe or cosmos as common thread in all happenings is reviewed. The missing of time is identified and concept of absence of time is put forward. The complex nature of time and the real and imaginary dimensions of physical time are also elaborately discussed together with human time- consciousness as past, present and future. (shrink)

Various understandings and definitions of time will be reviewed. The nature and structure of time will be reviewed and the concepts of time and passage of time will be refreshed. The fundamental role played by energy and four natural forces in the actions, reactions and interactions concerning matter, anti-matter, energy in space and time will be critically analyzed. The reality how time is constructed during the construction of materials will be presented and discussed. The classical and quantum ideas in this (...) regard will be comprehensively studied. How these ideas will give us a fresh insight about the nature, structure and role of time in the construction of materials through natural scientific and manmade processes will be highlighted. The relations among matter, anti-matter, energy and time will be freshly stated. The milli-, micro-, nano, pico-, femto-, atto-times will be qualitatively analyzed considering physical, inorganic, organic and bio-materials and their construction and structure. The physics of timelessness also will be put forward. -/- . (shrink)

Triadic (systemical) logic can provide an interpretive paradigm for understanding how quantum indeterminacy is a consequence of the formal nature of light in relativity theory. This interpretive paradigm is coherent and constitutionally open to ethical and theological interests. -/- In this statement: -/- (1) Triadic logic refers to a formal pattern that describes systemic (collaborative) processes involving signs that mediate between interiority (individuation) and exteriority (generalized worldview or Umwelt). It is also called systemical logic or the logic of relatives. The (...) term "triadic logic" emphasizes that this logic involves mediation of dualities through an irreducibly triadic formalism. The term "systemical logic" emphasizes that this logic applies to systems in contrast to traditional binary logic which applies to classes. The term "logic of relatives" emphasizes that this logic is background independent (in the sense discussed by Smolin ). -/- (2) An interpretive paradigm refers to a way of thinking that generates an understanding through concepts, their inter-relationships and their connections with experience. -/- (3) Coherence refers to holistic integrity or continuity in the meaning of concepts that form an interpretation or understanding. -/- (4) Constitutionally open refers to an inherent dependence in principle of an interpretation or understanding on something outside of a specific discipline's discourse or domain of inquiry (epistemic system). Interpretations that are constitutionally open are incomplete in themselves and open to responsive, interdisciplinary discourse and collaborative learning. (shrink)

Time is a complex category not only in philosophy but also in mathematics and physics. In one thought about time, the author accidentally discovered a new way to explain and solve problems related to time dilation, such as solving the problem of Muon particle when moving from a height of 10 km to the earth’s surface, while the Muon’s lifespan is only 2.2 microseconds, or explaining Michelson-Morley experiment using the new method. In addition, the author also prove that the speed (...) of light in vacuum is the maximum speed in the universe, and discovered the red shift effect while there is no increase in distance between objects. To do this, the author has built two axioms based on the discontinuity in the motion of the object and draw two consequences along with the law of conservation of time. (shrink)

This paper presents an attempt to define temporal coincidence starting from the first principles. The temporal coincidence defined here differs from Einstein’s simultaneity for it is invariant across inertial frames - not relative. The meaning and significance of temporal coincidence is derived from axioms of existence and it somehow relates to Kant’s notion of simultaneity. Consistentl y applied to the Special Theory of Relativity framework, temporal coincidence does not in any way create mathematical contradictions; however it allows looking at some (...) common relativity claims with a dose of scepticism. Time, as derived from Lorentz transformations, appears to be conventional in order to match the postulate of constancy of the speed of light. The relative simultaneity is only apparent due to that convention. There are insufficient grounds to claim that inertial systems moving relatively to each other have their own different temporal realities. Overall, the innate temporal logic we have is not erroneous and does not need to be replaced contrary to the claims of some relativity educators. (shrink)

Shadworth Hodgson offers an account of how philosophy relates to the science, both physical and psychological, in which three different conceptions of time can be identified. He distinguishes the methods of philosophy, involving analysis of the contents of immediate consciousness, and of science, which presumes the existence of world of common sense. Hodgson holds that philosophical analysis of immediate consciousness, or, the analysis of a present moment in experience, provides the ultimate justification for knowledge in science. Time as an object (...) of study in science must be distinguished from the temporal structure of immediate consciousness. Time as a target of scientific study is thus differentiable into time in physical science, and time in psychology, where the temporal characteristics of consciousness can be studied, but only from a perspective external to that consciousness. Each of those scientific conceptions of time still presuppose and are evidentially dependent on the analysis of immediate consciousness, itself already temporal. The result is that time as a fundamental unit of experience could not, even in principle, conflict with time as studied in science, because it is presupposed by and the evidential base for claims about time in science. (shrink)

How should we account for the extraordinary regularity in the world? Humeans and Non-Humeans sharply disagree. According to Non-Humeans, the world behaves in an extraordinarily regular way because of certain necessary connections in nature. However, Humeans have thought that Non-Humean views are metaphysically objectionable. In particular, there are two general metaphysical principles that Humeans have found attractive that are incompatible with all existing versions of Non-Humeanism. My goal in this paper is to develop a novel version of Non-Humeanism that is (...) consistent with (and even entails) both of these general metaphysical principles. By endorsing such a view, one can have the explanatory benefits of Non-Humeanism while at the same time avoiding two of the major metaphysical objections towards Non-Humeanism. (shrink)

According to orthodoxy, our best physical theories strongly support Eternalism over Presentism. Our goal is to argue against this consensus, by arguing that a certain overlooked aspect of our best physical theories strongly supports Presentism over Eternalism.

Determinism is frequently understood as implying the possibility of perfect prediction. This possibility then functions as an assumption in the Manipulation Argument for the incompatibility of free will and determinism. Yet this assumption is mistaken. As a result, arguments that rely on it fail to show that determinism would rule out human free will. We explain why determinism does not imply the possibility of perfect prediction in any world with laws of nature like ours, since it would be impossible for (...) an agent to predict with certainty any future event that is causally influenced by events outside her own backward light cone yet inside the backward light cone of the future event. This is the light-cone limit and it undermines the Manipulation Argument or limits what this argument can tell us about the relevance of determinism to free will. We also respond to objections that the light-cone limit is irrelevant to the Manipulation Argument. (shrink)

This paper considers two problems -- one in philosophy of religion and another in philosophy of physics -- and shows that the two problems have one solution. Some Christian philosophers have endorsed the views that (i) there was a first finitely long period of time, (ii) God is in time, and yet (iii) God did not have a beginning. If there was a first finitely long period of time and God is in time then there was a first finitely long (...) period of time in God's life. But if God's life includes a first finitely long period of time, then, on one initially intuitive conception of beginning to exist, God began to exist. Thus, at first glance, (i)-(iii) are not mutually compatible. Meanwhile, on a variety of proposals for quantum gravity theories or interpretations of quantum theory, space-time is not fundamental to physical reality and instead can (somehow) be explained in terms of yet more fundamental physical substructures. As I show, there is a strong intuition that if space-time is not fundamental to physical reality, then, even if there were a first finitely long period in the life of physical reality, physical reality would be beginningless. Thus, both theistic philosophers and philosophers of physics have developed theories on which some beginningless entities have a first finitely long temporal period in their lives and so both groups should be interested in developing criteria that distinguish such entities from entities with a beginning. In this paper, I offer one necessary (but not sufficient) condition, namely, that entities that begin to exist are absent from the closest possible worlds without time. The view that I defend has one significant upshot: no sound argument can use the mere fact (if it is a fact) that past time is finite to reach the conclusion that the totality of physical reality had a beginning. (shrink)

Abstract: Standing half wave particles at light speed twice in expansion-contraction comprise a static universe where two transverse fields 90° out of phase are the square of distance from each other. The universe has a static concept of time since the infinite universe is a static universe without a beginning or end. The square of distance is a point of reversal in expansion-contraction between the fields as a means to conserve energy. Photons on expansion in the electric field create matter (...) energy while photons on contraction in the magnetic field create light energy and gravitational pull toward the higher frequency energy. Also, the universe with matter has a moving physical concept of time from gravitational pull on expansion-contraction. (shrink)

Abstract: Standing half wave particles at light speed twice in expansion-contraction comprise a static universe where two transverse fields 90° out of phase are the square of distance from each other. The universe has a static concept of time since the infinite universe is a static universe without a beginning or end. The square of distance is a point of reversal in expansion-contraction between the fields as a means to conserve energy. Photons on expansion in the electric field create matter (...) energy while photons on contraction in the magnetic field create light energy and gravitational pull toward the higher frequency energy. Also, the universe with matter has a moving physical concept of time from gravitational pull on expansion-contraction. (shrink)

I discuss the ontological assumptions and implications of General Relativity. I maintain that General Relativity is a theory about gravitational fields, not about space-time. The latter is a more basic ontological category, that emerges from physical relations among all existents. I also argue that there are no physical singularities in space-time. Singular space-time models do not belong to the ontology of the world: they are not things but concepts, i.e. defective solutions of Einstein’s field equations. I briefly discuss the actual (...) implication of the so-called singularity theorems in General Relativity and some problems related to ontological assumptions of Quantum Gravity. (shrink)

Surface presentism is the combination of a general relativistic physics with a presentist metaphysics. In this paper, we provide an argument against this combination based on black holes. The problem focuses on the notion of an event horizon. We argue that the present locations of event horizons are ontologically dependent on future black hole regions, and that this dependence is incompatible with presentism. We consider five responses to the problem available to the surface presentist, and argue that none succeed. Surface (...) presentism thus faces the prospect of refutation based on evidence that confirms the existence of black holes. (shrink)

If there are fundamental laws of nature, can they fail to be exact? In this paper, I consider the possibility that some fundamental laws are vague. I call this phenomenon 'fundamental nomic vagueness.' I characterize fundamental nomic vagueness as the existence of borderline lawful worlds and the presence of several other accompanying features. Under certain assumptions, such vagueness prevents the fundamental physical theory from being completely expressible in the mathematical language. Moreover, I suggest that such vagueness can be regarded as (...) 'vagueness in the world.' For a case study, we turn to the Past Hypothesis, a postulate that (partially) explains the direction of time in our world. We have reasons to take it seriously as a candidate fundamental law of nature. Yet it is vague: it admits borderline (nomologically) possible worlds. An exact version would lead to an untraceable arbitrariness absent in any other fundamental laws. However, the dilemma between fundamental nomic vagueness and untraceable arbitrariness is dissolved in a new quantum theory of time's arrow. (shrink)

One of the most difficult problems in the foundations of physics is what gives rise to the arrow of time. Since the fundamental dynamical laws of physics are (essentially) symmetric in time, the explanation for time's arrow must come from elsewhere. A promising explanation introduces a special cosmological initial condition, now called the Past Hypothesis: the universe started in a low-entropy state. Unfortunately, in a universe where there are many copies of us (in the distant ''past'' or the distant ''future''), (...) the Past Hypothesis is not enough; we also need to postulate self-locating (de se) probabilities. However, I show that we can similarly use self-locating probabilities to strengthen its rival---the Fluctuation Hypothesis, leading to in-principle empirical underdetermination and radical epistemological skepticism. The underdetermination is robust in the sense that it is not resolved by the usual appeal to 'empirical coherence' or 'simplicity.' That is a serious problem for the vision of providing a completely scientific explanation of time's arrow. (shrink)

By deriving the Lorentz transformation from the absolute speed of light, Einstein demonstrated the relativistic variability of space and time, enabling him to explain length contraction and time dilation without recourse to a "luminiferous ether" or preferred frame of reference. He also showed that clocks synchronized at a distance via light signals are not synchronized in a frame of reference differing from that of the clocks. However, by mislabeling the relativity of synchrony the "relativity of simultaneity," Einstein implied that this (...) effect concerns an actual difference in times from one frame to another rather than merely a failure of clock synchronization across frames. As a theory of length contraction and time dilation on the basis of relative motion in the context of the absolute speed of light, special relativity is the definitive interpretation of the Lorentz transformation and the correct explanation of relativistic phenomena. The relativity of simultaneity, as I demonstrate, plays no role in this explanation but instead provides apparent justification for a view of time in which the present moment is frame-dependent. In contrast to its legitimate application, special relativity fails as a theory of time on the basis of the relativity of simultaneity. (shrink)

Cosmological boundary conditions for particles and fields are often discussed as a Cauchy problem, in which configurations and conjugate momenta are specified on an “initial” time slice. But this is not the only way to specify boundary conditions, and indeed in action-principle formulations we often specify configurations at two times and consider trajectories joining them. Here, we consider a classical system of particles interacting with short range two body interactions, with boundary conditions on the particles’ positions for an initial and (...) a final time. For a large number of particles that are randomly arranged into a dilute gas, we find that a typical system trajectory will spontaneously collapse into a small region of space, close to the maximum density that is obtainable, before expanding out again. If generalizeable, this has important implications for the cosmological arrow of time, potentially allowing a scenario in which both boundary conditions are generic and also a low-entropy state “initial” state of the universe naturally occurs. (shrink)

In this work we present an epistemic analysis of time phenomenon using the mathematical machinery of information theory and modular theory. By adopting limited commitment to the ontology of time evolution, and instead by mainly relying on the information that is in principle accessible to the observer, we find that the most primary aspect of the temporal experience, the perceived distinctiveness across the states of the world, emerges as a purely epistemic function. By analyzing the mathematical properties of this epistemic (...) function, we interpret it to be in principle insensitive to any ontic state of the world, which leads to the conclusion that the observer is subject to temporal experience irrespective of whether the underlying state of the world is dynamical or invariant. On the ground of the presented analysis, we also provide a solution to the conceptual challenge of non-equilibrium phenomena that faces the thermal time hypothesis. (shrink)

How long does a quantum particle take to traverse a classically forbidden energy barrier? In other words, what is the correct expression for quantum tunnelling time? This seemingly simple question has inspired widespread debate in the physics literature. I argue that we should not expect the orthodox interpretation of quantum mechanics to provide a unique correct expression for quantum tunnelling time, because to do so it would have to provide a unique correct answer to a question whose assumptions are in (...) tension with its core interpretational commitments. I explain how this conclusion connects to time’s special status in quantum mechanics, the meaningfulness of classically inspired concepts in different interpretations of quantum mechanics, the prospect of constructing experimental tests to distinguish between different interpretations, and the status of weak measurement in resolving questions about the histories of subensembles. (shrink)

Why does time reversal involve two operations, a temporal reflection and the operation of complex conjugation? Why is it that time reversal preserves position and reverses momentum and spin? This puzzle of time reversal in quantum mechanics has been with us since Wigner’s first presentation. In this paper, I propose a new solution to this puzzle. First, it is shown that the standard account of time reversal can be derived based on the assumption that the probability current is reversed by (...) the time reversal transformation. Next, this assumption is justified and the meaning of time reversal is clarified by analyzing the relationship between the rates of change and the instantaneous quantities which determine them. Finally, I explain how the new analysis help solve the puzzle of time reversal in quantum mechanics. (shrink)

Presentism is the view that only present things exist. So understood, presentism is primarily an ontological doctrine; it’s a view about what exists, absolutely and unrestrictedly. The view is the subject of extensive discussion in the literature on time and change, with much of it focused on the problems that presentism allegedly faces. Thus, most of the literature that frames the development of presentism has grown up either in formulating objections to the view (e.g., Sider 2001: 11–52), or in response (...) to such objections (e.g., Bigelow 1996; Markosian 2004), with exceptions to this largely coming via the ways in which presentism is motivated. This entry mirrors the structure of that literature, for the most part. Here’s the plan for what follows. We begin with a more detailed sketch of presentism, unpacking its commitments and motivations. Then, we move to consider several concerns raised for presentists. We use these to illustrate the breadth and severity of the challenges that presentism faces, as well as the range of different versions of presentism developed to help meet these challenges. (shrink)

The main research programs in quantum gravity tend to suggest in one way or another that most spacetime structures are not fundamental. At the same time, work in quantum foundations highlights fundamental features that are in tension with any straightforward space- time understanding. This paper aims to explore the little investigated but potentially fruitful links between these two fields.

Two views on the direction of time can be distinguished—primitivism and non-primitivism. According to the former, time’s direction is an in-built, fundamental property of the physical world. According to the latter, time’s direction is a derivative property of a fundamentally directionless reality. In the literature, non-primitivism has been widely supported since most our fundamental dynamical laws are time-reversal invariant. In this paper, I offer a way out to the primitivist. I argue that we do have good grounds to support a (...) primitive direction of time in the quantum realm. The rationale depends on exploiting the metaphysical and dynamical underdetermination of quantum theories to make a case in favor of primitivism. In particular, primitivism can be grounded in spontaneous collapse theories. The specific sense in which these theories capture a primitive direction of time is that, when the ontology of the theory is seriously taken into account, it does not remain invariant under time reversal. In taking GRW with a matter-density field, I will argue that primitivism about the direction of time can be defended in the quantum case. (shrink)

The article summarizes the software tool on astrophysical analysis with multi-wavelength space telescope data. It recaps the evidence analysis conducted on the Kerr-Newman black hole (KNBH). It was written prior to the article Research on the Kerr-Newman Black Hole in M82 Confirms Black Hole and White Hole Juxtapose not soon after the experiment. The conducted analysis suggested Hawking radiation is caused by the movement of ergosurfaces of the BH and serves as the primal evidence for black hole and white hole (...) juxtapose. A later data exploration was conducted with the radiation trails in the multi-wavelength data. The evidences produced corroborates with Yale professor Priyamvada Natarajan's black hole seeds theory. It implies that the electromagnetic dynamic of fusion and fission temperature determines the pressure of surface tension on the macro particles, and the mass density of the BH is determined by the electromagnetic tension between the outer ergosurface and inner ergosurface. The ring singularity of the BH and the Penrose-Hawking singularity of the BH determine the spin and gravitational singularity of the BH. Inside the ergosurfaces, the BH singularities' backward inflow causes the vicinity's rate on feeding the BH. It makes the active galactic nuclei (AGN) a semi-closed system. The density pressure is released on threshold. During the mass exchange observed by energy momentum upon the AGN's open, the macroparticle composition of the BH changes with the galactic event. This causes the expansion rate of the galaxy and contraction rate of the BH. AGN types and their relative motions determine the expansion rate of the cosmic universe in a generalized quantitative thinking. The article concludes that BH spin is caused by the asymmetric motions of AGN in the BH system. A set of the nuclear resonance caused by BH and white hole (WH) oscillation is processed with the same set of data. (shrink)

This paper is devoted to discussing the topological structure of the arrow of time. In the literature, it is often accepted that its algebraic and topological structures are that of a one-dimensional Euclidean space \, although a critical review on the subject is not easy to be found. Hence, leveraging on an operational approach, we collect evidences to identify it structurally as a normed vector space \\), and take a leap of abstraction to complete it, up to isometries, to the (...) real line. During the development of the paper, the space-time is recognized as a fibration, with the fibers being the sets of simultaneous events. The corresponding topology is also exposed: open sets naturally arise within our construction, showing that the classical space-time is non-Hausdorff. The transition from relativistic to classical regimes is explored too. (shrink)

This book defends a relational theory of the passage of time. The realist view of passage developed in this book differs from the robust, substantivalist position. According to relationism, passage is nothing over and above the succession of events, one thing coming after another. Causally related events are temporally arranged as they happen one after another along observers’ worldlines. There is no unique global passage but a multiplicity of local passages of time. After setting out this positive argument for relationism, (...) the author deals with five common objections to it: (a) triviality of deflationary passage, (b) a-directionality of passage, (c) the impossibility of experiencing passage, (d) fictionalism about passage, and (e) the incompatibility of passage with perduring objects. (shrink)

Hans Reichenbach’s posthumous book The Direction of Time ends somewhere between Socratic aporia and historical irony. Prompted by Feynman’s diagrammatic formulation of quantum electrodynamics, Reichenbach eventually abandoned the delicate balancing between the macroscopic foundation of the direction of time and microscopic descriptions of time order undertaken throughout the previous chapters in favor of an exclusively macroscopic theory that he had vehemently rejected in the 1920s. I analyze Reichenbach’s reasoning against the backdrop of the history of Feynman diagrams and the current (...) practice of particle physics. Building upon the debates about processes and conserved quantities between Wesley Salmon and Phil Dowe in the 1990s, and the exchange between Reichenbach and the gestalt theorist Kurt Lewin during the 1920s about topology and genidentity, I investigate whether the aporia about local time order could be avoided by following a strategy that Reichenbach adopted elsewhere in the book and develop a notion of functional genidentity that captures the practice of present-day elementary particle physics and the fact that Feynman diagrams have to be understood in the context of a complex mathematical description of scattering processes. (shrink)

Consider the following pair of theses: all fundamental physical objects are spatiotemporal and all non-fundamental physical objects are ultimately composed of fundamental objects. Work on the physics of quantum gravity suggests that spacetime is a non-fundamental, emergent phenomenon and thus that thesis is false. The fundamentals are non-spatiotemporal in nature. This paper will argue against on the grounds that non-fundamental spatiotemporal objects cannot be composed of fundamental non-spatiotemporal objects. So, assuming that spacetime is emergent, new metaphysical resources are needed to (...) explain the relationship between the fundamental objects posited by quantum gravity and spacetime. (shrink)

A number of approaches to quantum gravity (QG) seem to imply that spacetime does not exist. Philosophers are quick to point out, however, that the loss of spacetime should not be regarded as total. Rather, we should interpret these approaches as ones that threaten the fundamentality but not the existence of spacetime. In this paper, I argue for two claims. First, I argue that spacetime realism is not forced by QG; spacetime eliminativism remains an option. Second, I argue that eliminativism (...) provides a useful framework for developing two existing approaches to the metaphysics of QG, involving functionalism and mereology respectively. (shrink)