Frank Arntzenius has recently suggested that we should reject the standard view that the instantaneous state in classical mechanics consists of both the position and the velocity. In his view, the velocity as ordinarily defined-as the derivative of position with respect to time-cannot be genuinely instantaneous, and, thus, it should be excluded from the instantaneous state. After reviewing Bertrand Russell's traditional objections to the notion of an instantaneous velocity and suggesting that Russell's concerns (...) can be effectively answered, I argue that Arntzenius' attempt to show that the standard definition of velocity fails to yield an instantaneous property is not compelling either. Although I review several suggestions that Arntzenius makes against the existence of instantaneous velocity, much of his case rests upon an intuition, which has also appeared in the work of David Albert, about what is required of genuine instantaneous states. I argue in part that there is no reason to accept this intuition, and, thus, no reason to revise standard physical practice when it comes to the classical, instantaneous state. (shrink)

Zeno argued that since at any instant an arrow does not change its location, the arrow does not move at any time, and hence motion is impossible. I discuss the following three views that one could take in view of Zeno's argument:(i) the "at-at" theory, according to which there is no such thing as instantaneous velocity, while motion in the sense of the occupation of different locations at different times is possible,(ii) the "impetus" theory, according to which (...) class='Hi'>instantaneous velocities do exist but these are only contingently and causally related to the temporal developments of positions,(iii) the "no instants" theory, according to which instants in time do not exist, and hence instantaneous velocities do not exist, while motion, in the sense of different areas occupied during different time intervals, is possible.I argue that, despite the fact that there have been interesting and relevant developments in mathematics and physics since the time of Zeno, each of these views still has serious drawbacks. (shrink)

This paper will argue that the puzzles about instantaneous velocity, and rates of change more generally, are the result of a failure to recognize an ambiguity in the concept of an instant, and therefore of an instantaneous state. We will conclude that there are two distinct conceptions of a temporal instant: (i) instants conceived as fundamentally distinct zero-duration temporal atoms and (ii) instants conceived as the boundary of, or between,temporally extended durations. Since the concept of classical (...) class='Hi'>instantaneous velocity is well- defined only on the second conception of instants, we will conclude that this distinction allows us to avoid the above dilemma. If instantaneous velocity is well-defined then the states of a system at various instants are not logically distinct and thus we cannot generate Zeno’s paradox. However, if we assume that the instants are metaphysically distinct, then instantaneous velocity is not well-defined and thus the second horn of the dilemma about the causal-explanatory role of instantaneous velocity cannot be generated. (shrink)

There is a longstanding definition of instantaneous velocity. It saysthat the velocity at t 0 of an object moving along a coordinate line is r if and only if the value of the first derivative of the object's position function at t 0 is r. The goal of this paper is to determine to what extent this definition successfully underpins a standard account of motion at an instant. Counterexamples proposed by Michael Tooley (1988) and also by John (...) Bigelow and Robert Pargetter (1990) are reinforced and illuminated by considering the presence or absence of changes to the object's motion. (shrink)

Bošković’s distinction between two kinds of velocities – velocity in the first act, or potential velocity, and velocity in the second act, or actual velocity – is considered in respect to the concept of instantaneous velocity as defined by calculus differentialis. Contrary to the seeming inconsistency of Bošković’s duality of velocities and the concept of instantaneous velocity, due to a critical examination of logical and methodological foundations of the calculus, the article shows (...) that the duality of velocities is consistent with the interpretations of instantaneous velocity given by Oresme, Euler and Maclaurin, as with the definition of instantaneous velocity according to the rigorous Cauchyan founding of the calculus. Bošković’s duality of velocities is also shown to be consistent with Aristotelian-scholastic doctrine of potentiality and actuality, especially in its domain related to the nature of continuous motion. (shrink)

This book is a selection from the papers of the First International Conference on Superluminal Physics as New Fields of Research held at the University of New Mexico, Gallup Campus, USA, in July 2012. The editor have selected seven papers proposed by the following authors and co co-authors Kaizhe Guo Guo, Chongwu Guo Guo, Chen Jianguojianguo, Dong Jingfeng Jingfeng, Mi Haijiang Haijiang, Changwei Hu Hu, Yang Shijiashijia, Guli, and Fu Yuhua Yuhua.

The arrow paradox is an argument purported to show that objects do not really move. The two main metaphysics of motion, the At–At theory of motion and velocity primitivism, solve the paradox differently. It is argued that neither solution is completely satisfactory. In particular it is contended that there are no decisive arguments in favor of the claim that velocity as it is constructed in the At–At theory is a truly instantaneous property, which is a crucial assumption (...) to solve the paradox. If so the At–At theory faces the threat that most of our physical theories turn out to be non-Markovian. Finally it is considered whether all those threats and paradoxes are dispelled if only a new metaphysics of persistence is taken into account, namely four-dimensionalism. (shrink)

Most of our best scientific descriptions of the world employ rates of change of some continuous quantity with respect to some other continuous quantity. For instance, in classical physics we arrive at a particle’s velocity by taking the time-derivative of its position, and we arrive at a particle’s acceleration by taking the time-derivative of its velocity. Because rates of change are defined in terms of other continuous quantities, most think that facts about some rate of change obtain in (...) virtue of facts about those other continuous quantities. For example, on this view facts about a particle’s velocity at a time obtain in virtue of facts about how that particle’s position is changing at that time. In this paper we raise a puzzle for this orthodox reductionist account of rate of change quantities and evaluate some possible replies. We don’t decisively come down in favour of one reply over the others, though we say some things to support taking our puzzle to cast doubt on the standard view that spacetime is continuous. (shrink)

The arena of the philosophy of time has been largely concerned with deciding whether tense distinctions reflect absolute metaphysical distinctions or not. After bringing the debate over the metaphysical status of instantaneous velocity to bear on the debate over the nature of temporal passage, I argue that we should further investigate whether aspectual distinctions reflect objective and absolute metaphysical distinctions too. I conclude that those who think that being realist about tense uniquely makes room for the idea that (...) time passes should be realist about the progressive too. (shrink)

The rotating discs argument against perdurantism has been mostly discussed by metaphysicians, though the argument of course appeals to ideas from classical mechanics, especially about rotation. In contrast, I assess the RDA from the perspective of the philosophy of physics. I argue for three main conclusions. The first conclusion is that the RDA can be formulated more strongly than is usually recognized: it is not necessary to ‘imagine away’ the dynamical effects of rotation. The second is that in general relativity, (...) the RDA fails because of frame-dragging. The third conclusion is that even setting aside general relativity, the strong formulation of the RDA can after all be defeated, namely, by the perdurantist taking objects in classical mechanics to have only temporally extended temporal parts, which immediately blocks the RDA. Admittedly, this version of perdurantism defines persistence in a weaker sense of ‘definition’ than pointilliste versions that aim to define persistence assuming only instantaneous temporal parts. But I argue that temporally extended temporal parts can do the jobs within the endurantism– perdurantism debate that the perdurantist wants temporal parts to do and are supported by both classical and quantum mechanics. Introduction The story so far 2.1 The RDA 2.2 Intrinsic properties and the idea of velocity 2.2.1 The intrinsic–extrinsic distinction 2.2.2 Velocity to the rescue? 2.3 ‘Naturalism’ 2.4 The accompaniments of rotation 2.5 Two kinds of reply: against the consensus Describing rotation 3.1 Rotation is kinematic 3.2 Beware of rigidity 3.3 An improved RDA: allowing the actual accompaniments 3.4 The RDA fails in general relativity Perdurantism without tears: the classical case 4.1 Rejecting instantaneous temporal parts 4.2 Replying to the RDA 4.2.1 ‘Kinematics’ 4.2.2 ‘Dynamics’ 4.2.3 An ‘anti-pointilliste’ objection and reply 4.3 Intrinsic properties of non-instantaneous temporal parts 4.3.1 Can the perdurantist appeal to them? 4.3.2 Temporal intrinsicality at an instant is rare 4.3.3 A better reason for temporal intrinsicality 4.4 Non-instantaneous parts can do the jobs 4.4.1 Humean supervenience revisited 4.4.2 The problem of change 4.4.3 Puzzles of coincidence 4.5 Instantaneous velocity is hardly extrinsic Support from decoherence in quantum theory 5.1 Classical and quantum: relativizing the intrinsic–extrinsic distinction 5.1.1 Unitarity: momentum as temporally intrinsic 5.2 Position and existence as nomically extrinsic. (shrink)

Aristotle’s solution to Zeno’s arrow paradox differs markedly from the so called at-at solution championed by Russell, which has become the orthodox view in contemporary philosophy. The latter supposes that motion consists in simply being at different places at different times. It can boast parsimony because it eliminates velocity from the ontology. Aristotle, by contrast, solves the paradox by denying that the flight of the arrow is composed of instants; rather, on my reading, he holds that the flight is (...) a unity which is ontologically prior to the temporal parts that may be abstracted from it. I label this position temporal holism; and an entity that is ontological prior to its temporal parts lasting. Lasting, I argue, is the key to Aristotle’s solution to the arrow paradox, but it has received insufficient attention in the relevant literature. I therefore set out here to investigate lasting and highlight its major role in Aristotle’s metaphysics more broadly, and in his solution to other problems of change. I show, too, how lasting within a contemporary context underwrites a parsimonious and intuitive solution to the arrow paradox that retains instantaneous velocity, and hence solves a problem for those who think velocity is required within the ontology to underwrite certain causal roles. (shrink)

"One of Michael Blay's many fine achievements in Reasoning with the Infinite is to make us realize how velocity, and later instantaneous velocity, came to play a vital part in the development of a rigorous mathematical science of motion. ...

I claim that, if persisting objects have temporal parts, then there are non-supervenient relations between those temporal parts. These are relations which are not determined by intrinsic properties of the temporal parts. I use the Kripke-Armstrong 'rotating homogeneous disc' argument in order to establish this claim, and in doing so I defend and develop that argument. This involves a discussion of instantaneous velocity, and of the causes and effects of rotation. Finally, I compare alternative responses to the rotating (...) disc argument, and consider the implications of my arguments for the doctrines of Humean Supervenience and unrestricted mereology. (shrink)

This paper examines the role of Kant's theory of mathematical cognition in his phoronomy, his pure doctrine of motion. I argue that Kant's account of how we can construct the composition of motion rests on the construction of extended intervals of space and time, and the representation of the identity of the part–whole relations the construction of these intervals allow. Furthermore, the construction of instantaneous velocities and their composition also rests on the representation of extended intervals of space and (...) time, reflecting the general approach to instantaneous velocity in the eighteenth century. (shrink)

Objective: Stand-to-sit task is an important daily function, but there is a lack of research evidence on whether knee osteoarthritis affects the postural balance during the task. This study aimed to compare individuals with knee OA and asymptomatic controls in postural balance and identify kinematic and lower extremity muscle activity characteristics in individuals with knee OA during the stand-to-sit task.Methods: In total, 30 individuals with knee OA and 30 age-matched asymptomatic controls performed the 30-s Chair Stand Test at self-selected speeds. (...) Motion analysis data and surface electromyography were collected while participants performed the 30sCST. To quantify postural balance, the displacement of the center of mass and the peak instantaneous velocity of the CoM were calculated. The kinematic data included forward lean angles of the trunk and pelvic, range of motion of the hip, knee, and ankle joints in the sagittal plane. The averaged activation levels of gluteus maximus, vastus lateralis, vastus medialis, rectus femoris, biceps femoris, tibialis anterior, and medial head of gastrocnemius muscles were indicated by the normalized root mean square amplitudes.Results: Compared with the asymptomatic control group, the knee OA group prolonged the duration of the stand-to-sit task, demonstrated significantly larger CoM displacement and peak instantaneous CoM velocity in the anterior-posterior direction, reduced ankle dorsiflexion RoM, greater anterior pelvic tilt RoM, and lower quadriceps femoris and muscles activation level coupled with higher BF muscle activation level during the stand-to-sit task.Conclusion: This study indicates that individuals with knee OA adopt greater pelvic forward lean RoM and higher BF muscle activation level during the stand-to-sit task. However, these individuals exist greater CoM excursion in the anterior-posterior direction and take more time to complete the task. This daily functional activity should be added to the rehabilitation goals for individuals with knee OA. The knee OA group performs reduced ankle dorsiflexion RoM, quadriceps femoris, and TA activation deficit. In the future, the rehabilitation programs targeting these impairments could be beneficial for restoring the functional transfer in individuals with knee OA. (shrink)

Boškovićevo razlikovanje dviju vrsta brzina – brzine u prvom ozbiljenju , odnosno, potencijalne brzine i brzine u drugom ozbiljenju , odnosno, aktualne brzine – promišlja se u odnosu na koncept trenutne brzine kako je definira calculus differentialis. Nasuprot naizglednoj nedosljednosti Boškovićeve dualnosti brzina i koncepta trenutne brzine, tragom kritičkoga promišljanja logičkih i metodoloških temelja calculusa u članku se pokazuje kako je dualnost brzina dosljedna tumačenjima trenutne brzine koje daju Oresme, Euler i Maclaurin, kao i definiciji trenutne brzine temeljem strogog cauchyjevskog (...) utemeljenja calculusa. Boškovićeva dualnost brzina također je pokazana dosljednom aristotelijansko-skolastičkom nauku o možnosti i zbiljnosti, posebno u onoj njegovoj domeni koja se odnosi na narav neprekinutoga gibanja.Bošković’s distinction between two kinds of velocities – velocity in the first act , or potential velocity , and velocity in the second act , or actual velocity – is considered in respect to the concept of instantaneous velocity as defined by calculus differentialis. Contrary to the seeming inconsistency of Bošković’s duality of velocities and the concept of instantaneous velocity, due to a critical examination of logical and methodological foundations of the calculus, the article shows that the duality of velocities is consistent with the interpretations of instantaneous velocity given by Oresme, Euler and Maclaurin, as with the definition of instantaneous velocity according to the rigorous Cauchyan founding of the calculus. Bošković’s duality of velocities is also shown to be consistent with Aristotelian-scholastic doctrine of potentiality and actuality, especially in its domain related to the nature of continuous motion. (shrink)

Bošković’s distinction between two kinds of velocities – velocity in the first act, or potential velocity, and velocity in the second act, or actual velocity – is considered in respect to the concept of instantaneous velocity as defined by calculus differentialis. Contrary to the seeming inconsistency of Bošković’s duality of velocities and the concept of instantaneous velocity, due to a critical examination of logical and methodological foundations of the calculus, the article shows (...) that the duality of velocities is consistent with the interpretations of instantaneous velocity given by Oresme, Euler and Maclaurin, as with the definition of instantaneous velocity according to the rigorous Cauchyan founding of the calculus. Bošković’s duality of velocities is also shown to be consistent with Aristotelian-scholastic doctrine of potentiality and actuality, especially in its domain related to the nature of continuous motion. (shrink)

Until the Scientific Revolution, the nature and motions of heavenly objects were mysterious and unpredictable. The Scientific Revolution was revolutionary in part because it saw the advent of many mathematical tools—chief among them the calculus—that natural philosophers could use to explain and predict these cosmic motions. Michel Blay traces the origins of this mathematization of the world, from Galileo to Newton and Laplace, and considers the profound philosophical consequences of submitting the infinite to rational analysis. "One of Michael Blay's many (...) fine achievements in _Reasoning with the Infinite_ is to make us realize how velocity, and later instantaneous velocity, came to play a vital part in the development of a rigorous mathematical science of motion."—Margaret Wertheim, _New Scientist_. (shrink)

Until the Scientific Revolution, the nature and motions of heavenly objects were mysterious and unpredictable. The Scientific Revolution was revolutionary in part because it saw the advent of many mathematical tools—chief among them the calculus—that natural philosophers could use to explain and predict these cosmic motions. Michel Blay traces the origins of this mathematization of the world, from Galileo to Newton and Laplace, and considers the profound philosophical consequences of submitting the infinite to rational analysis. "One of Michael Blay's many (...) fine achievements in _Reasoning with the Infinite_ is to make us realize how velocity, and later instantaneous velocity, came to play a vital part in the development of a rigorous mathematical science of motion."—Margaret Wertheim, _New Scientist_. (shrink)

We investigate in detail the electromagnetic fields of a uniformly accelerated charge, in order to ascertain whether such a charge does ‘emit’ radiation, especially in view of the Poynting flow computed at large distances and taken as an evidence of radiation emitted by the charge. In this context, certain important aspects of the fields need to be taken into account. First and foremost is the fact that in the case of a uniformly accelerated charge, one cannot ignore the velocity (...) fields. This then leads to other equally vital points. The net field energy turns out to be exactly the same as that of a non-accelerated charge having a uniform velocity equal to the instantaneous velocity of the uniformly accelerated charge. Further, the Poynting vector, seen with respect to the ’present’ location of the uniformly accelerated charge, during the deceleration phase, possesses everywhere a radial component pointing inward toward the charge, becoming nil when the charge becomes momentarily stationary, and during the acceleration phase, points away from the charge position. Last, but not least, when the leading spherical front of the relativistically beamed Poynting flux, advances forward at a large time t to a far-off distance \, the charge too is not lagging far behind. In fact, these relativistically beamed fields, increasingly resemble fields of a charge moving in an inertial frame with a uniform velocity \, with a convective flow of fields in that frame along with the movement of the charge. There is no other Poynting flow in the far-zones that could be termed as radiation emitted by the charge which, in turn, is fully consistent with the absence of radiation reaction and is also fully conversant with the strong principle of equivalence. (shrink)

Kripke-Armstrongovim argumentom tvrdi se da branilac postojanja temporalnih delova materijalnih objekata ne može da utvrdi da li usamljeni homogeni disk sačinjen od kontinuirane materije rotira oko svoje ose ili miruje. Perdurantista ne može da razlikuje dve mogućnosti pozivajući se na različite trenutne brzine trenutnih temporalnih delova diska, zbog toga što bi time prekršio tezu hjumovske supervenijencije. U ovom radu ću, sledeći Džeremija Baterfilda, pokazati kako se na KripkeArmstrongov izazov može odgovoriti zadržavajući hjumovsku supervenijenciju: pozivanjem na različite trenutne brzine netrenutnih temporalnih (...) delova Kripke-Armstrongovog usamljenog diska. (shrink)

The derivative is a basic concept of differential calculus. However, if we calculate the derivative as change in distance over change in time, the result at any instant is 0/0, which seems meaningless. Hence, Newton and Leibniz used the limit to determine the derivative. Their method is valid in practice, but it is not easy to intuitively accept. Thus, this article describes the novel method of differential calculus based on the double contradiction, which is easier to accept intuitively. Next, the (...) geometrical meaning of the double contradiction is considered as follows. A tangent at a point on a convex curve is iterated. Then, the slope of the tangent at the point is sandwiched by two kinds of lines. The first kind of line crosses the curve at the original point and a point to the right of it. The second kind of line crosses the curve at the original point and a point to the left of it. Then, the double contradiction can be applied, and the slope of the tangent is determined as a single value. Finally, the meaning of this method for the foundation of mathematics is considered. We reflect on Dehaene’s notion that the foundation of mathematics is based on the intuitions, which evolve independently. Hence, there may be gaps between intuitions. In fact, the Ancient Greeks identified inconsistency between arithmetic and geometry. However, Eudoxus developed the theory of proportion, which is equivalent to the Dedekind Cut. This allows the iteration of an irrational number by rational numbers as precisely as desired. Simultaneously, we can define the irrational number by the double contradiction, although its existence is not guaranteed. Further, an area of a curved figure is iterated and defined by rectilinear figures using the double contradiction. (shrink)

Since his Metaphysische Anfangsgründe der Naturwissenschaft was first published in 1786, controversy has surrounded Immanuel Kant’s conception of matter. In particular, the justification for both his dynamical theory of matter and the related dismissal of mechanical philosophy are obscure. In this paper, I address these longstanding issues and establish that Kant’s dynamism rests upon Leibnizian, metaphysical commitments held by Kant from his early pre-Critical texts on natural philosophy to his major critical works. I demonstrate that, throughout his corpus and inspired (...) by Leibniz, Kant endorses the a priori law of continuity of alteration as a truth of metaphysics, according to which all alterations in experience must occur gradually through all intervening degrees. The principle thus legislates against mechanical philosophy’s absolutely impenetrable atoms, as they would would involve instantaneous changes of velocity in impact. This reveals the metaphysical incoherencies in mechanical philosophy and leaves Kant’s own dynamical theory of matter, grounded on material forces, as the only viable approach to physical explanation. Subsequently, I demonstrate that Kant nevertheless made conceptual space in his system for the theoretical consideration of mechanical explanations, which makes manifest one of the positive roles that the faculty of reason can play with respect to natural science. (shrink)

The author has recently shown that a mathematical question regarding the fundamental constituents of hardrons cannot be resolved unless the classical axioms of nonfinite mathematics are revised in such a way as to produce a new theory of particle motion in continuous space-time. Under this new theory, the instantaneous position of a moving object has a magnitude that is increasing as the object's velocity. The purpose of this paper is to show that, quite apart from the question of (...) Cantorian axiomatics, the new theory of motion is more consistent with what physicists really believe than the traditional theory of motion. (shrink)

We found that phase cone clustering patterns in EEG ripple bands demonstrate an increased turnover rate in epileptogenic zones compared to adjacent regions. We employed 256 channel EEG data collected in four adult subjects with refractory epilepsy. The analysis was performed in the 80–150 and 150–250 Hz ranges. Ictal onsets were documented with intracranial EEG recordings. Interictal scalp recordings, free of epileptiform patterns, of 240-s duration, were selected for analysis for each subject. The data was filtered, and the instantaneous (...) phase was extracted after the Hilbert transformation. Spatiotemporal contour plots of the unwrapped instantaneous phase with 1.0 ms intervals were constructed using a montage layout of the 256 electrode positions. Stable phase cone patterns were selected based on criteria that the sign of spatial gradient did not change for a minimum of three consecutive time samples and the frame velocity was consistent with known propagation velocities of cortical axons. These plots exhibited increased dynamical formation and dissolution of phase cones in the ictal onset zones, compared to surrounding cortical regions, in all four patients. We believe that these findings represent markers of abnormally increased cortical excitability. They are potential tools that may assist in localizing the epileptogenic zone. (shrink)

The rigid recoil of a crystal is the accepted mechanism for the Mössbauer effect. It’s at odds with the special theory of relativity which does not allow perfectly rigid bodies. The standard model of particle physics which includes QED should not allow any signals to be transmitted faster than the speed of light. If perturbation theory can be used, then the X-ray emitted in a Mössbauer decay must come from a single nuclear decay vertex at which the 4-momentum is exactly (...) conserved in a Feynman diagram. Then the 4-momentum of the final state Mössbauer nucleus must be slightly off the mass shell. This off-shell behavior would be followed by subsequent diffusion of momentum throughout the crystal to bring the nucleus back onto the mass shell and the crystal to a final relaxed state in which it moves rigidly with the appropriate recoil velocity. This mechanism explains the Mössbauer effect at the microscopic level and reconciles it with relativity. Because off-mass-shell quantum mechanics is required, the on-mass-shell theories developed originally for the Mössbauer effect are inadequate. Another possibility is that that the recoil response involves a non-perturbative effect in the standard model which could allow for a non-local instantaneous momentum transfer between the crystal and the decay, as proposed for example by Preparata and others in super-radiance theory. The recoil time of the crystal is probably not instantaneous, and if it could be measured, one could distinguish between various theories. An experiment is proposed in this paper to measure this time. The idea is to measure the total energy radiated due to bremsstrahlung from a charged Mössbauer crystal which has experienced a recoil. Using Larmor’s formula, along with corrections to it, allows one to design an experiment. The favored idea is to use many small nano-spheres of Mössbauer-active metals, whose outer surfaces are charged. The energy radiated then varies as the charge squared divided by the recoil time. This can then be measured with the extreme sensitivity available in Mössbauer experiments. If it turns out that experiments prove the need for off-mass-shell theory, then this would have profound implications for all of condensed matter physics. It would mean that an off-mass-shell theory like those considered by Stueckelberg, Horwitz, Piron, Greenberger, and many others are required to describe nature. The inclusion of these would be a major shift in the foundations. It would mean that there are new dynamic variables—the rest masses of particles. The ability to measure the diffusion relaxation time should prove useful also in chemical analysis, and provide a new class of analytical methods for material science. This problem is also interesting because the Mössbauer effect is a phenomenon where the solid-state environment dramatically and indisputably influences the probability of a nuclear process. (shrink)

The distinction itself is best explained as follows. At the empirical level (at the bottom), there are curves, or functions, or laws, such as PV = constant the Boyle’s example, or a = M/r 2 in Newton’s example. The first point is that such formulae are actually ambiguous as to the hypotheses they represent. They can be understood in two ways. In order to make this point clear, let me first introduce a terminological distinction between variables and parameters. Acceleration and (...) distance (a and r) are variables in Newton’s formula because they represent quantities that are more or less directly measured. The distinction between what is directly measured and what it is not is to be understood relative the context. All I mean is that values of acceleration and distance are determined independently of the hypothesis, or theory, under consideration. I do not mean that their determination involves no kind of inference at all. For instance, acceleration is the instantaneous change in velocity per unit time, and this is not something that is directly determined from raw data that records the position of the moon at consecutive points in time. It is consistent with that raw data that the motion of the moon is actually discontinuous, so that the moon has no acceleration. So, there are definitely theoretical assumptions make about the moon’s motion that are used to estimate the moon’s acceleration at a particular time. But these assumptions are not unique to Newton’s theory. The same assumptions are also made by the rival hypotheses under consideration. In fact, the existence of quantities such as instantaneous acceleration is only called into question by the far more recent theory of quantum mechanics. Likewise, in the case of Boyle’s law, there is no controversy in viewing the volume of the trapped air as being determined in a way that does not make use of the theory that Boyle is introducing. (shrink)

Now imagine that this accelerated gold nucleus has a head-on collision with a second nuclear pancake, a gold nucleus accelerated to the same ultra-relativistic velocity but in the opposite direction. Momentarily, the two pancakes in this light-speed head-on collision will overlap. The masses of the nuclei have been increased by a factor of 108, and the mass of each is contained in a volume that has been reduced by a factor of 108. As a result, neglecting the fuzzing effects (...) of the Heisenberg uncertainty principle, the instantaneous density of.. (shrink)

In his Concept of Nature Whitehead gives the following definition of the term “co-presence”: I call two event-particles which on some or other system of measurement are in the same instantaneous space ‘co-present’ event-particles. Then it is possible that A and B may be co-present, and that A and C may be co-present, but that B and C may not be co-present. For example, at some inconceivable distance from us there are events co-present with us now and also co-present (...) with the birth of Queen Victoria. If A and B are co-present there will be some systems in which A precedes B and some in which B precedes A. Also there can be no velocity quick enough to carry a material particle from A to B or from B to A. (shrink)

It is shown that the well-known disparity in classical electrodynamics between the power losses calculated from the radiation reaction and that from Larmor’s formula, is succinctly understood when a proper distinction is made between quantities expressed in terms of a “real time” and those expressed in terms of a retarded time. It is explicitly shown that an accelerated charge, taken to be a sphere of vanishingly small radius \, experiences at any time a self-force proportional to the acceleration it had (...) at a time \ earlier, while the rate of work done on the charge is obtained by a scalar product of the self-force with the instantaneous value of its velocity. Now if the retarded value of acceleration is expressed in terms of the present values of acceleration, then we get the rate of work done according to the radiation reaction equation, however if we instead express the present value of velocity in terms of its time-retarded value, then we get back the familiar Larmor’s radiation formula. From this simple relation between the two we show that they differ because Larmor’s formula, in contrast with the radiation reaction, is written not in terms of the real-time values of quantities specifying the charge motion but is instead expressed in terms of the time-retarded values. Moreover, it is explicitly shown that the difference in the two formulas for radiative power loss exactly matches the difference in the temporal rate of the change of energy in the self-fields between the retarded and real times. From this it becomes obvious that the ad hoc introduction of an acceleration-dependent energy term, usually referred to in the prevalent literature as Schott-term, in order to make the two formulas comply with each other, is redundant. (shrink)

I explore two logical possibilities for the discretization of time, termed ``instantaneous" and ``smeared". These are found by discretizing a continuous theory, and the resulting structure of configuration space and velocities are described. It is shown that results known in numerical methods for integration of dynamical systems preclude the existence of a system with fixed discrete time step which conserves fundamental charges universally, and a method of avoidance of this ``no-go" theorem is constructed. Finally the implications of discrete time (...) upon quantum cosmology are discussed. NB : At this point this paper is a draft, citations and formatting are not completed. (shrink)

Movement, Velocity, and Rhythm from a Psychoanalytic Perspective: Variable Speed(s) explores philosophical and psychoanalytic theories, as well as artworks, that show sensible bodily rituals for reviving our social and subjective lives. With a wide range of contributors from interdisciplinary backgrounds, it informs readers on how to find rituals for syncing ourselves with others and world rhythms. It will be essential reading for Lacanian psychoanalysts in practice and in training, as well as anyone interested in rhythm at the intersection of (...) Lacanian psychoanalysis and continental philosophy. (shrink)

"Berlin 1936 : du balcon de mes grands-parents, angle Kurfürstendamm et Wilmersdorferstrasse, j'assiste à la parade d'ouverture des jeux Olympiques. Debout dans une voiture découverte, un personnage en uniforme brun salue, le bras tendu, la foule enthousiaste qui l'acclame. Je demande à ma mère : "Qui est cet homme"? Elle me tire par le bras vers le fond de l'appartement et me dit seulement : "Viens, ce n'est pas pour toi". ".

ABSTRACT This paper offers an account of intending to self-deceive which opposes that provided by standard intentionalist accounts of self-deception. According to my account, self-deception is attained instantaneously: to intend to self-deceive that P is thereby to self-deceive that P. Relating this to the concepts of evidence, belief and self-awareness, I develop an account of self-deception which holds that self-deceivers misrepresent themselves as believing what they profess to believe. I argue that my account yields solutions to the central problems of (...) self-deception – the static problem and the dynamic problem – while remaining faithful to the phenomena of self-deception. (shrink)

The standard definition of an instantaneous temporal part cannot properly deal with cases involving time travel. This paper provides a new definition of an instantaneous temporal part by appealing to David Lewis's distinction between external time and personal time. The new definition avoids the problems because it does not allow more than one instantaneous temporal part of an object at each moment of its personal time. We argue that this new definition, combined with our new perdurantist semantic (...) thesis, deals with cases of time travel successfully. (shrink)

ABSTRACT In this journal, Middleton and Murgueitio Ramírez argue that absolute velocity is measurable, contrary to the received wisdom. Specifically, they claim that ‘there exists at least one reasonable analysis of measurement according to which the speedometer in [a world called “the Basic World”] measures the absolute velocity of the car.’ In this note, I critically respond to that claim: the analysis of measurement that Middleton and Murgueitio Ramírez propose is not reasonable; nor does it entail that absolute (...) velocities are measurable. (shrink)

Background Healthcare is predicated on the use of biotechnology and medical technology, both of which are indispensable in diagnosis, treatment, and most aspects of patient care. It is therefore imperative that justifications for use of new technologies are appropriate, with the technologies working as advertised. In this paper, I consider philosophical accounts of how such justifications are made. Methods Critical philosophical reflection and analysis. Results I propose that justification in many prominent accounts is based on the designer’s professional experience and (...) on expert testimony. I argue, however, that professional designers are not in a position to justify a new biotechnology or medical device if the justification is based on testimony or past experience of presumably similar technologies. I argue (1) that similarity judgments offered by instantaneous experts cannot be viewed as contributing (epistemically) to evidential justification of new and unproven technologies; and (2) that designers and manufacturers cannot endorse a technology’s effective function in a patient-care context until it has been successfully used in that context. Conclusion I show that an expert’s past professional experiences can never predict or justify the impact of a novel technology on human health. This is because any new technology leads to the introduction of new mechanisms with unprecedented functions. The new technology therefore needs to be studied in situ and justified as a newly created mechanism within the relevant healthcare setting. Ultimately, justifications of this type rely on the scientific community and society engaging in repeated experimentation and observation of the technology, and confirming its successful use. (shrink)

Starting from the formal expressions of the hydrodynamical (or “local”) quantities employed in the applications of Clifford algebras to quantum mechanics, we introduce—in terms of the ordinary tensorial language—a new definition for the field of a generic quantity. By translating from Clifford into tensor algebra, we also propose a new (nonrelativistic) velocity operator for a spin- ${\frac{1}{2}}$ particle. This operator appears as the sum of the ordinary part p/m describing the mean motion (the motion of the center-of-mass), and of (...) a second part associated with the so-called Zitterbewegung, which is the spin “internal” motion observed in the center-of-mass frame (CMF). This spin component of the velocity operator is nonzero not only in the Pauli theoretical framework, i.e., in the presence of external electromagnetic fields with a nonconstant spin function, but also in the Schrödinger case, when the wavefunction is a spin eigenstate. Thus, one gets even in the latter case a decomposition of the velocity field for the Madelung fluid into two distinct parts, which constitutes the nonrelativistic analogue of the Gordon decomposition for the Dirac current. Explicit calculations are presented for the velocity field in the particular cases of the hydrogen atom, of a spherical well potential, and of an electron in a uniform magnetic field. We find, furthermore, that the Zitterbewegung motion involves a velocity field which is solenoidal, and that the local angular velocity is parallel to the spin vector. In the presence of a nonuniform spin vector (Pauli case) we have, besides the component of the local velocity normal to the spin (present even in the Schrödinger theory), also a component which is parallel to the curl of the spin vector. (shrink)

In Quodlibet XV q.13, Henry of Ghent considers whether the Virgin Mary was immaculately conceived. He argues that she was not, but rather possessed sin only at the first instant of her existence. Because Henry’s defense of this position involves an elaborate discussion of motion and mutation, his discussion marks an important contribution to medieval discussions of Aristotelian natural philosophy. In fact, a number of scholars have identified Henry’s discussion as the source of an unusual fourteenth-century theory of change referred (...) to as “quasi-Aristotelianism” . My aim in the paper is two-fold: first, to show that Henry's position is not quasi-Aristotelian in the sense that scholars have supposed; second, to show that, even so, his discussion in q. 13 does involve a novel interpretation of Aristotle’s account of instantaneous change. (shrink)

In Quodlibet XV q.13, Henry of Ghent considers whether the Virgin Mary was immaculately conceived. He argues that she was not, but rather possessed sin only at the first instant of her existence. Because Henry’s defense of this position involves an elaborate discussion of motion and mutation, his discussion marks an important contribution to medieval discussions of Aristotelian natural philosophy. In fact, a number of scholars have identified Henry’s discussion as the source of an unusual fourteenth-century theory of change referred (...) to as “quasi-Aristotelianism” (so-called because the account purports to be Aristotelian but is not). My aim in the paper is two-fold: first, to show that Henry's position is not quasi-Aristotelian in the sense that scholars have supposed; second, to show that, even so, his discussion in q. 13 does involve a novel interpretation of Aristotle’s account of instantaneous change. (shrink)

(1992). The instantaneous impulse construction as a formula for central force motion on an arbitrary plane curve with respect to an arbitrary force centre in the plane of that curve. Annals of Science: Vol. 49, No. 4, pp. 369-375.

In this essay, I first set out the principles of change, paying particular attention to the need for a support for all changes and to the need for prime matter. I then discuss the nature of time, arguing that time is not actually composed of durationless instants but that instants can be understood as limits to an infinite process of potential division. I then give a definition of instants in terms of intervals and propose a way of modeling them. In (...) the next section I bring together the two previous sections by explaining change as an instantaneous process that does not involve actual instants. In the final section I draw out a larger metaphysical moral that emphasizes the role of potentiality and sees the potentiality in change and the potentiality in time as but different aspects of the same radical potentiality in nature. (shrink)

In this paper we discuss ethical implications of the use of mobile phone apps in the control of the COVID-19 pandemic. Contact tracing is a well-established feature of public health practice during infectious disease outbreaks and epidemics. However, the high proportion of pre-symptomatic transmission in COVID-19 means that standard contact tracing methods are too slow to stop the progression of infection through the population. To address this problem, many countries around the world have deployed or are developing mobile phone apps (...) capable of supporting instantaneous contact tracing. Informed by the on-going mapping of ‘proximity events’ these apps are intended both to inform public health policy and to provide alerts to individuals who have been in contact with a person with the infection. The proposed use of mobile phone data for ‘intelligent physical distancing’ in such contexts raises a number of important ethical questions. In our paper, we outline some ethical considerations that need to be addressed in any deployment of this kind of approach as part of a multidimensional public health response. We also, briefly, explore the implications for its use in future infectious disease outbreaks. (shrink)