We summarize published hole transit-timemeasurements for hydrogenated amorphous silicon, microcrystalline silicon, and light-emitting nanoporous silicon in terms of drift mobilities and dispersion parameters. For amorphous and microcrystalline silicon, the anomalously dispersive measurements are broadly consistent with multiple-trapping by bandtail traps with an exponential distribution of energy depths. One unexplained result has been that the trap emission prefactor frequency ? is about 1000 times smaller in microcrystalline silicon than in amorphous silicon. We present a model incorporating both (...) detailed-balance effects and a previously proposed Meyer?Neldel variation of ? with trap-depth; the model accounts for the factor 1000. We discuss general trap distributions incorporating variations of both trap depth and prefactor frequency; a model for which dispersion is due entirely to prefactor variation accounts for measurements on nanoporous silicon. (shrink)
A theoretical device, which incorporates the functions of clock, rod, nonrotating platform, and accelerometer, and whose operation depends on the properties of light rays and free particles, is defined. The device, which we call a metrosphere, is simple enough that it can be introduced at the starting point of relativity theory and versatile enough that it can serve as an aid in the development and conceptualization of the theory. Relative to an inertial frame, a moving metrosphere undergoes a Lorentz-Fitzgerald contraction (...) and the associated clock exhibits a Lorentz-Larmor rate retardation. From this fact and the assumption that there exists one inertial frame, it is possible to generate the kinematical results of special relativity. A metrosphere provides an observer with a local frame of reference, hence it is well adapted to the needs of general relativity, allows the equivalence principle to be introduced in a straightforward manner, and permits a smooth transition from special relativity to general relativity. (shrink)
We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never (...) in favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define “the same incoming state” and “the same detector” when comparing the settings with and without tunnel potential. The arrival timemeasurements are expressed in the time-covariant approach, but we also allow the detection to be a localization measurement at a later time. (shrink)
We consider the problem of measurement using the Lindblad equation, which allows the introduction of time in the interaction between the measured system and the measurement apparatus. We use analytic results, valid for weak system-environment coupling, obtained for a two-level system in contact with a measurer (Markovian interaction) and a thermal bath (non-Markovian interaction), where the measured observable may or may not commute with the system-environment interaction. Analysing the behavior of the coherence, which tends to a value asymptotically close (...) to zero, we obtain an expression for the time of measurement which depends only on the system-measurer coupling, and which does not depend on whether the observable commutes with the system-bath interaction. The behavior of the coherences in the case of strong system-environment coupling, found numerically, indicates that an increase in this coupling decreases the measurement time, thus allowing our expression to be considered the upper limit for the duration of the process. (shrink)
This paper revisits some early applications of audio-visual imaging technologies used in physiology in a dialogue with reflections on Henri Bergson’s philosophy. It focuses on the aspects of time and memory in relation to spatial representations of movement measurements and critically discusses them from the perspective of the observing participant and the public exhibitions of scientific films. Departing from an audio-visual example, this paper is informed by a thick description of the philosophical implications and contemporary discourses surrounding the (...) scientific inventions, technologies and theories of moving image technologies, representations of time, and the measurement of bodies in motion such as those by the French physiologist Étienne-Jules Marey. The application of Bergson’s thinking will show how the scientific graphing and representations of the body through technologies inevitably stand in tension with the limits and potentials of the ‘human apparatus’ and its abilities, filters and internalised processes of perception, memory and consciousness. It proposes an ontological approach to scientific imaging technologies and a critical engagement with the ‘realism’ debate in the discourse of audio-visual media. (shrink)
By analyzing a gedanken experiment designed to measure the distance l between two spatially separated points, we find that this distance cannot be measured with uncertainty less than (ll 2 P) 1/3 , considerably larger than the Planck scale lP (or the string scale in string theories), the conventional-wisdom uncertainty in distance measurements. This limitation to space-timemeasurements is interpreted as resulting from quantum fluctuations of space-time itself. Thus, at very short distance scales, space-time is (...) “foamy.” This intrinsic foaminess of space-time provides another source of noise in the interferometers. The LIGO/VIRGO and LISA generations of gravity-wave interferometers, through future refinements, are expected to reach displacement noise levels low enough to test our proposed degree of foaminess in the structure of space-time. (shrink)
We investigate the thesis of Aharonov, Bergmann, and Lebowitz that time-symmetry holds in ensembles defined by both an initial and a final condition, called preand postselected ensembles. We distinguish two senses of time symmetry and show that the first one, concerning forward directed and time reversed measurements, holds if the measurement process is ideal, but fails if the measurement process is non-ideal, i.e., violates Lüders's rule. The second kind of time symmetry, concerning the interchange of (...) initial and final conditions, fails even in the case of ideal measurements. Bayes's theorem is used as a primary tool for calculating the relevant probabilities. We are critical of the concept that a pair of vectors in Hilbert space, characterizing the initial and final conditions, can be considered to constitute a generalized quantum state. (shrink)
The formal time symmetry of the quantum measurement process is extensively discussed. Then, the origin of the alleged association between a fixed temporal direction and quantum measurements is investigated. It is shown that some features of such an association might arise from epistemological rather than purely physical assumptions. In particular, it is brought out that a sequence of statements bearing on quantum measurements may display intrinsic asymmetric properties, irrespective of the location of corresponding measurements in (...) class='Hi'>time t of the Schrodinger equation. The situation of an observer performing two measurements in two opposite directions of t is eventually investigated. Essential differences are found between two descriptions of this situation: the internal one (taking only into account what is recorded in the observer's memory) and the external one (whereby the observer is considered as a quantum system ruled by the Schrodinger equation). Finally, a method allowing several observers to establish a correspondence between their memory sizes is analyzed. The most important facts that usually lead to the associating of a preferential temporal direction with quantum measurements may be inferred from this correspondence. (shrink)
We demonstrate in this paper that the probabilities for sequential measurements have features very different from those of single-timemeasurements. First, they cannot be modelled by a classical stochastic process. Second, they are contextual, namely they depend strongly on the specific measurement scheme through which they are determined. We construct Positive-Operator-Valued measures (POVM) that provide such probabilities. For observables with continuous spectrum, the constructed POVMs depend strongly on the resolution of the measurement device, a conclusion that persists (...) even if we consider a quantum mechanical measurement device or the presence of an environment. We then examine the same issues in alternative interpretations of quantum theory. We first show that multi-time probabilities cannot be naturally defined in terms of a frequency operator. We next prove that local hidden variable theories cannot reproduce the predictions of quantum theory for sequential measurements, even when the degrees of freedom of the measuring apparatus are taken into account. Bohmian mechanics, however, does not fall in this category. We finally examine an alternative proposal that sequential measurements can be modeled by a process that does not satisfy the Kolmogorov axioms of probability. This removes contextuality without introducing non-locality, but implies that the empirical probabilities cannot be always defined (the event frequencies do not converge). We argue that the predictions of this hypothesis are not ruled out by existing experimental results (examining in particular the “which way” experiments); they are, however, distinguishable in principle. (shrink)
Prospect Theory (PT) is widely regarded as the most promising descriptive model for decision making under uncertainty. Various tests have corroborated the validity of the characteristic fourfold pattern of risk attitudes implied by the combination of probability weighting and value transformation. But is it also safe to assume stable PT preferences at the individual level? This is not only an empirical but also a conceptual question. Measuring the stability of preferences in a multi-parameter decision model such as PT is far (...) more complex than evaluating single-parameter models such as Expected Utility Theory under the assumption of constant relative risk aversion. There exist considerable interdependencies among parameters such that allegedly diverging parameter combinations could in fact produce very similar preference structures. In this paper, we provide a theoretic framework for measuring the (temporal) stability of PT parameters. To illustrate our methodology, we further apply our approach to 86 subjects for whom we elicit PT parameters twice, with a time lag of 1 month. While documenting remarkable stability of parameter estimates at the aggregate level, we find that a third of the subjects show significant instability across sessions. (shrink)
Presenting the history of space-time physics, from Newton to Einstein, as a philosophical development DiSalle reflects our increasing understanding of the connections between ideas of space and time and our physical knowledge. He suggests that philosophy's greatest impact on physics has come about, less by the influence of philosophical hypotheses, than by the philosophical analysis of concepts of space, time, and motion and the roles they play in our assumptions about physical objects and physical measurements. This (...) way of thinking leads to new interpretations of the work of Newton and Einstein and the connections between them. It also offers new ways of looking at old questions about a priori knowledge, the physical interpretation of mathematics, and the nature of conceptual change. Understanding Space-Time will interest readers in philosophy, history and philosophy of science, and physics, as well as readers interested in the relations between physics and philosophy. (shrink)
In this article I investigate several possibilities to define the concept of “temporal non-locality” within the standard framework of quantum theory. In particular, I analyze the notions of “temporally non-local states”, “temporally non-local events” and “temporally non-local observables”. The idea of temporally non-local events is already inherent in the standard formalism of quantum mechanics, and Basil Hiley recently defined an operator in order to measure the degree of such a temporal non-locality. The concept of temporally non-local states enters as soon (...) as “clock-representing states” are introduced in the context of special and general relativity. It is discussed in which way temporally non-local measurements may find an interesting application for experiments which test temporal versions of Bell inequalities. (shrink)
Studies of implicit learning have shown that individuals exposed to a rule-governed environment often learn to exploit 'rules' which describe the structural relationship between environmental events. While some authors have interpreted such demonstrations as evidence for functionally separate implicit learning systems, others have argued that the observed changes in performance result from explicit knowledge which has been inadequately assessed. In this paper we illustrate this issue by considering one commonly used implicit learning task, the Serial reaction time task, and (...) outline what we see as an important problem associated with each of the commonly used methods used to assess explicit knowledge. This is that each measure requires a form of response which is dependent on the subjects having some knowledge of the serial-order of the sequence. We argue that such methods, or more specifically their analyses, seriously underestimate other sources of knowledge, which may be available to subjects during their performance of the SRT task. In support of this argument we demonstrate that subjects' serial-order knowledge can, in principle, be independent of subjects' knowledge of the statistical structure of the sequence, and we propose an alternative method for analysing performance on the Generate task which avoids this problem. (shrink)
Proofs have been given that the light-cone approximation can be analyzed in terms of the extended quantum-mechanical description of the space-timemeasurements by the complex numbers. It is then proved that the so established description is able to support both the asymptotical scale-invariant cross sections and the threshold behavior of the high-energy production processes.
Determining the moment at which a visual recognition process is completed, or the order in which various processes come into play, are fundamental steps in any attempt to understand human recognition abilities, or to replicate the corresponding hierarchy of neuronal mechanisms within artificial systems. Common experimental paradigms for addressing these questions involve the measurement and/or comparison of backward-masking (or RSVP: Rapid Serial Visual Presentation) psychometric functions and of physiological EEG/MEG/LFP signals (peak latencies, differential activities, single-trial decoding techniques). I review and (...) illustrate four common mistakes that scientists tend to make when using these paradigms, and explain the conceptual fallacies that motivate their reasoning. First, contrary to collective intuition, presentation times or SOA masking thresholds cannot be taken to reflect, directly or indirectly, the timing of relevant brain processes. Second, psychophysical or electrophysiological measurements should not be compared without assessing potential physical differences between experimental stimulus sets. Third, such comparisons should not be performed in any manner contingent on subjective responses, so as to avoid response biases. Last, the filtering of electrophysiological signals alters their temporal structure, and thus precludes their interpretation in terms of time course. Practical solutions are proposed to overcome these common mistakes. (shrink)
An analysis of the two routes through which one may disentangle a quantum system from a measuring apparatus, hence protect the state vector of a single quantum system from being disturbed by the measurement, reveals that the argument from protected measurement to the reality of the state vector of a single quantum system is valid but unsound. From this negative result I draw some lessons on the available "interpretations" of quantum theory and on the debate on the quantum measurement problem.
The 'Reaction experiment with Hipp chronoscope' is one of the classical experiments of modern psychology. This paper investigates the technological contexts of this experiment. It argues that the development of time measurement and communication in other areas of science and technology (astronomy, the clock industry) were decisive for shaping the material culture of experimental in psychology. The chronoscope was constructed by Matthaus Hipp (1813-1893) in the late 1840s. In 1861, Adolphe Hirsch (1830-1901) introduced the chronoscope for measuring the 'physiological (...)time' of astronomical observers. Hirsch's observatory at Neuchatel (Switzerland) served to control the quality of clocks produced in the nearby Jura mountains. Hipp provided the observatory with a telegraphic system that sent time signals to the centers of clock production. Time telegraphy constituted the stable surroundings of the reaction time experiments carried out by both astronomers and psychologists. This technology permitted precise measurements of short time intervals and offered to Hirsch, as well as to Wilhelm Wundt (1832-1920), a useful metaphor for conceptualizing their respective 'epistemic objects'. But time telegraphy also limited the possibilities of the experimental work conducted within its framework. In particular, noise from outside and inside the research sites at Neuchatel, Leipzig and elsewhere disturbed the precise communication of time. (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)
Bergson argues for free will by showing that the arguments against it come from a confusion of different conceptions of time. As opposed to physicists' idea of measurable time, in human experience life is perceived as a continuous and unmeasurable flow rather than as a succession of marked-off states of consciousness--something that can be measured not quantitatively, but only qualitatively. His conclusion is that free will is an observable fact.
This paper outlines some key issues that arise when agency and temporality are considered jointly, from the perspective of psychology, cognitive neuroscience, phenomenology, and action theory. I address the difference between time simpliciter and time as represented as it figures in phenomena like intentional binding, goal-oriented action plans, emulation systems, and ‘temporal agency’. An examination of Husserl’s account of time consciousness highlights difficulties in generalizing his account to include a substantive notion of agency, a weakness inherited by (...) explanatory projects like neurophenomenology. I conclude by sketching a project analogous to the projects in neurophenomenology, based on Thompson’s naïve action theory. (shrink)
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)
McTaggart famously argued that time is unreal. Today, almost no one agrees with his conclusion. But his argument remains the locus classicus for both the A-theory and the B-theory of time. I show how McTaggart’s argument provided the impetus for both of these opposing views of the nature of time. I also present and defend what I take to be the correct view of the nature of time.
Heidegger claims in Being and Time that Bergson fails to overcome traditional ontology because his concept of time is fundamentally Aristotelian. On the basis of this hasty dismissal, it is tempting to conclude that Heidegger was not terribly interested in Bergson or that he only wanted to prevent readers from confusing his view of time with Bergson’s. To the contrary, a survey of Heidegger’s early lectures and writings on the issue of time reveals a strong interest (...) in Bergson and an acknowledgement of his importance as a pivotal thinker concerning time. In fact, Heidegger appropriates key aspects of Bergsonism, such as Bergson’s way of contrasting the measurement of time and its experiential origins, revealing that his ambivalence toward Bergson initially arises from concerns about his method and his concept of life rather than his understanding of time. (shrink)
Part I: Dimensions of time's enigma -- Is time real? -- Eleaticism, temporality, and time -- The makings of a temporal universe -- Pastness and futurity -- Synchronicity and synchronicity -- Temporal pace and measurement -- Presentness or the present -- Aristotle's real account of time -- Parmenidean time and the impossible now -- Cosmic motion and the speed of time -- Time as the motion of the cosmos -- Time as the (...) cosmos itself -- Time as motion and all change -- Temporal cognition and the return of the now -- Real temporality in an Aristotelian world -- Does Aristotle refute eleaticism? -- Bisection argument I -- Bisection argument II -- Bisection argument III -- Plotinus' vitalistic platonism and the real origins of time -- Temporality, eternality, and Plotinus' new metaphysic -- Plotinus' critique of Aristotelian motion -- Indefinite temporality and the measure of motion -- Plotinus' neoplatonic account of time. (shrink)
TimeTime is what clocks measure. The three key features of time are that it orders events in sequence one after the other; it specifies how long any event lasts; and it specifies when events occur. Yet despite 2,500 years of investigating time, many issues about it are unresolved. Here is a list of the […].
In this paper we examine how English and Mandarin speakers think about time, and we test how the patterns of thinking in the two groups relate to patterns in linguistic and cultural experience. In Mandarin, vertical spatial metaphors are used more frequently to talk about time than they are in English; English relies primarily on horizontal terms. We present results from two tasks comparing English and Mandarin speakers’ temporal reasoning. The tasks measure how people spatialize time in (...) three-dimensional space, including the sagittal (front/back), transverse (left/right), and vertical (up/down) axes. Results of Experiment 1 show that people automatically create spatial representations in the course of temporal reasoning, and these implicit spatializations differ in accordance with patterns in language, even in a non-linguistic task. Both groups showed evidence of a left-to-right representation of time, in accordance with writing direction, but only Mandarin speakers showed a vertical top-to-bottom pattern for time (congruent with vertical spatiotemporal metaphors in Mandarin). Results of Experiment 2 confirm and extend these findings, showing that bilinguals’ representations of time depend on both long-term and proximal aspects of language experience. Participants who were more proficient in Mandarin were more likely to arrange time vertically (an effect of previous language experience). Further, bilinguals were more likely to arrange time vertically when they were tested in Mandarin than when they were tested in English (an effect of immediate linguistic context). (shrink)
The recent surge of interest in the origin of the temporal asymmetry of thermodynamical systems (including the accessible part of the universe itself) has put forward two possible explanatory approaches to this age-old problem. Hereby we show that there is a third possible alternative, based on the generalization of the classical (“Boltzmann–Schuetz”) anthropic fluctuation picture of the origin of the perceived entropy gradient. This alternative (which we dub the Acausal-Anthropic approach) is based on accepting Boltzmann's statistical measure at its face (...) value, and accomodating it within the quantum cosmological concept of the multiverse. We argue that conventional objections raised against the Boltzmann–Schuetz view are less forceful and serious than it is usually assumed. A fortiori, they are incapable of rendering the generalized theory untenable. On the contrary, this analysis highlights some of the other advantages of the multiverse approach to the thermodynamical arrow of time. (shrink)
Weak measurements offer new insights into the behavior of quantum systems. Combined with post-selection, quantum mechanics predicts a range of new experimentally testable phenomena. In this paper I consider weak measurements performed on time-dependent pre- and post-selected ensembles, with emphasis on the decay of excited states. The results show that the standard exponential decay law is a limiting case of a more general law that depends on both the time of post-selection and the choice of final (...) state. The generalized law is illustrated for two interesting choices of post-selection. (shrink)
It sometimes happens that advances in one area of philosophy can be applied to a quite different area of philosophy, and that the result is an unexpected significant advance. I think that this is true of the philosophy of time and meta-ethics. Developments in the philosophy of time have led to a new understanding of the relation between semantics and metaphysics. Applying these insights to the field of meta-ethics, I will argue, can suggest a new position with respect (...) to moral discourse and moral reality. This new position retains the advantages of theories like moral realism and naturalism, yet is immune to many of their difficulties. (shrink)
This article addresses the question whether supertasks are possible within the context of non-relativistic quantum mechanics. The supertask under consideration consists of performing an infinite number of quantum mechanical measurements in a finite amount of time. Recent arguments in the physics literature claim to show that continuous measurements, understood as N discrete measurements in the limit where N goes to infinity, are impossible. I show that there are certain kinds of measurements in quantum mechanics for (...) which these arguments break down. This suggests that there is a new context in which quantum mechanics, in principle, permits the performance of a supertask. (shrink)
It is proposed that the recent controversy over "time-symmetric quantum counterfactuals" (TSQCs), based on the Aharonov-Bergmann-Lebowitz Rule for measurements of pre- and post-selected systems, can be clarified by taking TSQCs to be counterfactuals with a specific type of compound antecedent. In that case, inconsistency proofs such as that of Sharp and Shanks (1993) are not applicable, and the main issue becomes not whether such statements are true, but whether they are nontrivial. The latter question is addressed and answered (...) in the negative. Thus it is concluded that TSQCs, understood as counterfactuals with a compound antecedent, are true but only trivially so, and provide no new contingent information about specific quantum systems (except in special cases already identified in literature). (shrink)
Our article is an overview of a selection of findings in physics relating to the issue of time—we do not present in it any “time theory” of our own. After making some general remarks on the issue of time, we present historical outline and a brief description of the current state of time interval measurements. Subsequently, we go on to discuss certain (relating to the concept of time) consequences of both theories of relativity: special (...) and general. Here, time is a geometrical component of space-time continuum. Following section is dedicated to time in the so-called Hamiltonian formulations of the theory of particles, where it appears as a parameter of evolution. The last section contains remarks referring to certain attempts of going beyond the recognized physical theories relating to the question of time. (shrink)
In the context of a discussion of time symmetry in the quantum mechanical measurement process, Aharonov et al. (1964) derived an expression concerning probabilities for the outcomes of measurements conducted on systems which have been pre- and postselected on the basis of both preceding and succeeding measurements. Recent literature has claimed that a resulting "time-symmetrized" interpretation of quantum mechanics has significant implications for some basic issues, such as contextuality and determinateness, in elementary, nonrelativistic quantum mechanics. Bub (...) and Brown (1986) have shown that under the standard interpretation of the aforementioned expression, these claims employ ensembles which are not well defined. It is argued here that under a counterfactual interpretation of the expression, these claims may be understood as employing well-defined ensembles; it is shown, however, that such an interpretation cannot be reconciled with the standard interpretation of quantum mechanics. (shrink)
A time-symmetric formulation of nonrelativistic quantum mechanics is developed by applying two consecutive boundary conditions onto solutions of a time- symmetrized wave equation. From known probabilities in ordinary quantum mechanics, a time-symmetric parameter P0 is then derived that properly weights the likelihood of any complete sequence of measurement outcomes on a quantum system. The results appear to match standard quantum mechanics, but do so without requiring a time-asymmetric collapse of the wavefunction upon measurement, thereby realigning quantum (...) mechanics with an important fundamental symmetry. (shrink)
Respecting and protecting the confidentiality of data and the privacy of individuals regarding the information that they have given as participants in a research project is a cornerstone of complying with accepted research standards. However, in longitudinal studies, establishing and maintaining privacy is often challenging because of the necessity of repeated contact with participants. A novel internet-based solution is introduced here, which maintains privacy while at the same time ensures linkage of data to individual participants in a repeated measures (...) design. With the use of the anonymous repeated measurements via email (ARME) procedure, two separate one-way communication systems are established through ad hoc email accounts and a secure study website. Strengths and limitations of the approach are discussed. (shrink)
The paper extends the framework of outcomes in branching space-time (Kowalski and Placek ) by assigning probabilities to outcomes of events, where these probabilities are interpreted either epistemically or as weighted possibilities. In resulting models I define the notion of common cause of correlated outcomes of a single event, and investigate which setups allow for the introduction of common causes. It turns out that a deterministic common cause can always be introduced, but (surprisingly) only special setups permit the introduction (...) of truly stochastic common causes. I analyse next the Bell-Aspect experiment and derive the Bell-CH inequalities. I observe that we postulate there not a common cause for outcomes of a single event but rather a common common cause that accounts for outcomes of many events, where 'events' mean 'measurements with (different) directions of polarization'. Since the inequalities are violated, I claim that no causal story can be told about the Bell correlations, where causality is subliminal and restricted by screening-off condition. Similarly, given certain intuitive principles, no deterministic story can be told about these correlations. (shrink)
The nondecay probability of an unstable particle at a definite moment of time is investigated provided this particle existed at all earlier observation moments separated with the time interval Δ. Using the usual postulates for quantum measurements it is proved that this probability is described by the exponential function of Δ>0, and it tends to 1 as Δ → 0. An approximate formula is found for the effective decay width Γ(Δ) appearing in the case of multiple (...) class='Hi'>measurements. It is shown that Γ(Δ) → 0 as Δ → 0. For Δ → ∞, the width Γ(Δ) → Γ0, with Γ0 being the standard decay with in Weisskopf-Wigner theory. At finite δ's Γ(Δ) may be smaller or greater than Γ0 depending on the parameters of the theory. (shrink)
If it is possible to think that human life is temporal as a whole, and we can make sense of Wittgenstein’s claim that the psychological phenomena called ‘dispositions’ do not have genuine temporal duration on the basis of a distinction between dispositions and other mental processes, we need a compelling account of how time applies to these dispositions. I undertake this here by examining the concept of expectation, a disposition with a clear nexus to time by the temporal (...) point at which the expectation is satisfied. However, it seems that we cannot always identify the beginning of an expectation, and in a few cases, its end. If so, the reduction of expectations to neural events or accompanying feelings which spread over time in the usual way seems a hard enterprise, because these processes, much as other physical processes, have a definite and largely measurable time span. Only at a higher level, that is, as part of human life, expectation can be said to be temporal. (shrink)
The discussion of a particular kind of interpretation of the energy-time uncertainty relation, the “pragmatic time” version of the ETUR outlined in Part I of this work [measurement duration (pragmatic time) versus uncertainty of energy disturbance or measurement inaccuracy] is reviewed. Then the Aharonov-Bohm counter-example is reformulated within the modern quantum theory of unsharp measurements and thereby confirmed in a rigorous way.
Quantum limitations arising in measurements of a classical force acting on a quantum harmonic oscillator are studied in connection with the problem of increasing the sensitivity of gravity wave experiments. The physical nature of possible limits of sensitivity is elucidated. It originates in a degree of an uncertainty of an observable used for detecting an external force. This uncertainty can be made as small as desired for all moments of time for the observables corresponding to quantum integrals of (...) motion. Advantages of integrals of motion with continuous spectra (like the operator of the initial coordinate) over integrals with discrete spectra (like energy) are discussed. An example of an observable suitable for exact continuous measurements of an external force independently on the initial state of the system—the difference link operator—is given. The general rule for constructing such “optimal observables” can be derived from the quantum optimal filtration theory. It is shown using Ehrenfest's theorem that no quantum limitations exist in principle for the accuracy of measurements of an external classical force acting on an arbitrary quantum system: limitations can appear only due to nonadequate measuring procedures. The general problem of finding the initial quantum states possessing the best sensitivity to an external force is formulated. The parametrically excited oscillator is briefly discussed, and it is shown that measuring the suitable integral of motion one can achieve the great gain in sensitivity. The role of quantum interference effects is emphasized. (shrink)