2,658 research outputs found
Hidden measurements, hidden variables and the volume representation of transition probabilities
We construct, for any finite dimension , a new hidden measurement model
for quantum mechanics based on representing quantum transition probabilities by
the volume of regions in projective Hilbert space. For our model is
equivalent to the Aerts sphere model and serves as a generalization of it for
dimensions . We also show how to construct a hidden variables scheme
based on hidden measurements and we discuss how joint distributions arise in
our hidden variables scheme and their relationship with the results of Fine.Comment: 23 pages, 1 figur
Quantum Particles as Conceptual Entities: A Possible Explanatory Framework for Quantum Theory
We put forward a possible new interpretation and explanatory framework for
quantum theory. The basic hypothesis underlying this new framework is that
quantum particles are conceptual entities. More concretely, we propose that
quantum particles interact with ordinary matter, nuclei, atoms, molecules,
macroscopic material entities, measuring apparatuses, ..., in a similar way to
how human concepts interact with memory structures, human minds or artificial
memories. We analyze the most characteristic aspects of quantum theory, i.e.
entanglement and non-locality, interference and superposition, identity and
individuality in the light of this new interpretation, and we put forward a
specific explanation and understanding of these aspects. The basic hypothesis
of our framework gives rise in a natural way to a Heisenberg uncertainty
principle which introduces an understanding of the general situation of 'the
one and the many' in quantum physics. A specific view on macro and micro
different from the common one follows from the basic hypothesis and leads to an
analysis of Schrodinger's Cat paradox and the measurement problem different
from the existing ones. We reflect about the influence of this new quantum
interpretation and explanatory framework on the global nature and evolutionary
aspects of the world and human worldviews, and point out potential explanations
for specific situations, such as the generation problem in particle physics,
the confinement of quarks and the existence of dark matter.Comment: 45 pages, 10 figure
God may not play dice, but human observers surely do
We investigate indeterminism in physical observations. For this, we introduce
a distinction between genuinely indeterministic (creation-1 and discovery-1)
observational processes, and fully deterministic (creation-2 and discovery-2)
observational processes, which we analyze by drawing a parallel between the
localization properties of microscopic entities, like electrons, and the
lateralization properties of macroscopic entities, like simple elastic bands.
We show that by removing the randomness incorporated in certain of our
observational processes, acquiring over them a better control, we also alter
these processes in such a radical way that in the end they do not correspond
anymore to the observation of the same property. We thus conclude that a
certain amount of indeterminism must be accepted and welcomed in our physical
observations, as we cannot get rid of it without also diminishing our
discriminative power. We also provide in our analysis some elements of
clarification regarding the non-spatial nature of microscopic entities, which
we illustrate by using an analogy with the process of objectification of human
concepts. Finally, the important notion of relational properties is properly
defined, and the role played by indeterminism in their characterization
clarified
Detection of gravity modes in the massive binary V380 Cyg from Kepler spacebased photometry and high-resolution spectroscopy
We report the discovery of low-amplitude gravity-mode oscillations in the
massive binary star V380 Cyg, from 180 d of Kepler custom-aperture space
photometry and 5 months of high-resolution high signal-to-noise spectroscopy.
The new data are of unprecedented quality and allowed to improve the orbital
and fundamental parameters for this binary. The orbital solution was subtracted
from the photometric data and led to the detection of periodic intrinsic
variability with frequencies of which some are multiples of the orbital
frequency and others are not. Spectral disentangling allowed the detection of
line-profile variability in the primary. With our discovery of intrinsic
variability interpreted as gravity mode oscillations, V380 Cyg becomes an
important laboratory for future seismic tuning of the near-core physics in
massive B-type stars.Comment: 5 pages, 4 figures, 2 tables. Accepted for publication in MNRAS
Letter
Testing the asymptotic relation for period spacings from mixed modes of red giants observed with the Kepler mission
Dipole mixed pulsation modes of consecutive radial order have been detected
for thousands of low-mass red-giant stars with the NASA space telescope Kepler.
Such modes have the potential to reveal information on the physics of the deep
stellar interior. Different methods have been proposed to derive an observed
value for the gravity-mode period spacing, the most prominent one relying on a
relation derived from asymptotic pulsation theory applied to the gravity-mode
character of the mixed modes. Our aim is to compare results based on this
asymptotic relation with those derived from an empirical approach for three
pulsating red-giant stars. We developed a data-driven method to perform
frequency extraction and mode identification. Next, we used the identified
dipole mixed modes to determine the gravity-mode period spacing by means of an
empirical method and by means of the asymptotic relation. In our methodology,
we consider the phase offset, , of the asymptotic
relation as a free parameter. Using the frequencies of the identified dipole
mixed modes for each star in the sample, we derived a value for the
gravity-mode period spacing using the two different methods. These differ by
less than 5%. The average precision we achieved for the period spacing derived
from the asymptotic relation is better than 1%, while that of our data-driven
approach is 3%. Good agreement is found between values for the period spacing
derived from the asymptotic relation and from the empirical method.
Full abstract in PDF file.Comment: 14 pages, 13 figures, accepted for publication in A&
Concepts and Their Dynamics: A Quantum-Theoretic Modeling of Human Thought
We analyze different aspects of our quantum modeling approach of human
concepts, and more specifically focus on the quantum effects of contextuality,
interference, entanglement and emergence, illustrating how each of them makes
its appearance in specific situations of the dynamics of human concepts and
their combinations. We point out the relation of our approach, which is based
on an ontology of a concept as an entity in a state changing under influence of
a context, with the main traditional concept theories, i.e. prototype theory,
exemplar theory and theory theory. We ponder about the question why quantum
theory performs so well in its modeling of human concepts, and shed light on
this question by analyzing the role of complex amplitudes, showing how they
allow to describe interference in the statistics of measurement outcomes, while
in the traditional theories statistics of outcomes originates in classical
probability weights, without the possibility of interference. The relevance of
complex numbers, the appearance of entanglement, and the role of Fock space in
explaining contextual emergence, all as unique features of the quantum
modeling, are explicitly revealed in this paper by analyzing human concepts and
their dynamics.Comment: 31 pages, 5 figure
Unifying Decision-Making: a Review on Evolutionary Theories on Rationality and Cognitive Biases
In this paper, we make a review on the concepts of rationality across several
different fields, namely in economics, psychology and evolutionary biology and
behavioural ecology. We review how processes like natural selection can help us
understand the evolution of cognition and how cognitive biases might be a
consequence of this natural selection. In the end we argue that humans are not
irrational, but rather rationally bounded and we complement the discussion on
how quantum cognitive models can contribute for the modelling and prediction of
human paradoxical decisions
Mechanical energy in toddler gait - A trade-off between economy and stability?
Mechanical energy expenditure was investigated in children who are just learning to walk and compared with adult mechanical energy expenditure during walking. First, we determined whether the inverted pendulum (IP) mechanism of energy exchange was present in toddlers. It seems that new walkers partially make use of this energy saving mechanism, but it is less efficient than in adults. The reduced recovery values (R=40% at optimal speeds in toddlers compared to 70% in adults) can be explained by their low self-selected walking speed in combination with their tossing gait (large vertical oscillations of the body) and by the observation that during as much as 25–50% of the gait cycle kinetic and potential energy are oscillating in-phase. The second step was to calculate positive external mechanical work (Wext). Since the IP mechanism is less efficient in toddlers, more mass-specific positive work has to be performed to lift and accelerate the centre of mass than in adults walking at the same speed, even when differences in body size are taken into account. The amount of positive internal work (Wint,k) necessary to move the body segments relative to the centre of mass was the third parameter we calculated. In toddlers Wint,k is largely determined by the kinetic energy of the lower limb. Compared to adults, toddlers have to perform less mass-specific work per unit distance to accelerate the body segments since the upper body is kept relatively stiff during walking and there is no arm swing. Apart from work performed on the centre of mass and work performed to move the body segments relative to the centre of mass, when walking some work is also performed during double contact as both legs are pushing against each other. Two methods were used to calculate this amount of work, both leading to the same conclusions. Mass-specific work during double contact is small in toddlers compared to adults because of their low walking speed. Finally the total amount of mechanical work performed in toddlers was compared to the work production observed in adults. Wext seems to be the major determinant for total mechanical energy expenditure. At intermediate froude numbers work production is comparable between adults and toddlers, but at low and high froude numbers Wtot increases due to the steep increases in Wext. Despite the fact that mechanical work requirements in toddler gait are underestimated if work during double contact is not taken into account, it is not a major determinant of the energy cost of walking
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