4,829 research outputs found
Quantum Machine and SR Approach: a Unified Model
The Geneva-Brussels approach to quantum mechanics (QM) and the semantic
realism (SR) nonstandard interpretation of QM exhibit some common features and
some deep conceptual differences. We discuss in this paper two elementary
models provided in the two approaches as intuitive supports to general
reasonings and as a proof of consistency of general assumptions, and show that
Aerts' quantum machine can be embodied into a macroscopic version of the
microscopic SR model, overcoming the seeming incompatibility between the two
models. This result provides some hints for the construction of a unified
perspective in which the two approaches can be properly placed.Comment: 21 pages, 5 figures. Introduction and Conclusions improved, minor
corrections in several sections. Accepted for publication in Foundations of
Physic
The pulsations and potential for seismology of B stars
We review the nature of the oscillations of main-sequence and supergiant
stars of spectral type B. Seismic tuning of the interior structure parameters
of the Cep stars has been achieved since three years. The results are
based on frequencies derived from long-term monitoring and progress in this
area is rapid. Oscillations in mid-B stars as well as Be stars are well
established by now, but we lack good mode identification to achieve seismic
modelling. We provide recent evidence of g-mode pulsations in supergiant B
stars. The spherical wavenumbers of their modes are yet unidentified,
preventing seismic probing of such evolved hot stars at present. Improving the
situation for the three groups of g-mode oscillators requires multi-site
long-term high-resolution spectroscopy in combination with either space
photometry or ground-based multicolour photometry. The CoRoT programme and its
ground-based programme will deliver such data in the very near future.Comment: Invited talk, Proc. SOHO 18 / GONG 2006 / HELAS I Conference: Beyond
the spherical Sun. ESA SP-624, K. Fletcher, ed., in press, 8 pages with 5
figure
Quantum Structures: An Attempt to Explain the Origin of their Appearance in Nature
We explain the quantum structure as due to the presence of two effects, (a) a
real change of state of the entity under influence of the measurement and, (b)
a lack of knowledge about a deeper deterministic reality of the measurement
process. We present a quantum machine, where we can illustrate in a simple way
how the quantum structure arises as a consequence of the two mentioned effects.
We introduce a parameter epsilon that measures the size of the lack of
knowledge on the measurement process, and by varying this parameter, we
describe a continuous evolution from a quantum structure (maximal lack of
knowledge) to a classical structure (zero lack of knowledge). We show that for
intermediate values of epsilon we find a new type of structure, that is neither
quantum nor classical. We apply the model that we have introduced to situations
of lack of knowledge about the measurement process appearing in other regions
of reality. More specifically we investigate the quantum-like structures that
appear in the situation of psychological decision processes, where the subject
is influenced during the testing, and forms some of his opinions during the
testing process. Our conclusion is that in the light of this explanation, the
quantum probabilities are epistemic and not ontological, which means that
quantum mechanics is compatible with a determinism of the whole.Comment: 22 pages, 8 figure
Entanglement of Conceptual Entities in Quantum Model Theory (QMod)
We have recently elaborated 'Quantum Model Theory' (QMod) to model situations
where the quantum effects of contextuality, interference, superposition,
entanglement and emergence, appear without the entities giving rise to these
situations having necessarily to be of microscopic nature. We have shown that
QMod models without introducing linearity for the set of the states. In this
paper we prove that QMod, although not using linearity for the state space,
provides a method of identification for entangled states and an intuitive
explanation for their occurrence. We illustrate this method for entanglement
identification with concrete examples
Estimating the conditions for polariton condensation in organic thin-film microcavities
We examine the possibility of observing Bose condensation of a confined
two-dimensional polariton gas in an organic quantum well. We deduce a suitable
parameterization of a model Hamiltonian based upon the cavity geometry, the
biexciton binding energy, and similar spectroscopic and structural data. By
converting the sum-over-states to a semiclassical integration over
-dimensional phase space, we show that while an ideal 2-D Bose gas will not
undergo condensation, an interacting gas with the Bogoliubov dispersion
close to will undergo Bose condensation at a given
critical density and temperature. We show that is sensitive
to both the cavity geometry and to the biexciton binding energy. In particular,
for strongly bound biexcitons, the non-linear interaction term appearing in the
Gross-Pitaevskii equation becomes negative and the resulting ground state will
be a localized soliton state rather than a delocalized Bose condensate.Comment: 2 figure
Interpreting Quantum Particles as Conceptual Entities
We elaborate an interpretation of quantum physics founded on the hypothesis
that quantum particles are conceptual entities playing the role of
communication vehicles between material entities composed of ordinary matter
which function as memory structures for these quantum particles. We show in
which way this new interpretation gives rise to a natural explanation for the
quantum effects of interference and entanglement by analyzing how interference
and entanglement emerge for the case of human concepts. We put forward a scheme
to derive a metric based on similarity as a predecessor for the structure of
'space, time, momentum, energy' and 'quantum particles interacting with
ordinary matter' underlying standard quantum physics, within the new
interpretation, and making use of aspects of traditional quantum axiomatics.
More specifically, we analyze how the effect of non-locality arises as a
consequence of the confrontation of such an emerging metric type of structure
and the remaining presence of the basic conceptual structure on the fundamental
level, with the potential of being revealed in specific situations.Comment: 19 pages, 1 figur
Ephemeral properties and the illusion of microscopic particles
Founding our analysis on the Geneva-Brussels approach to quantum mechanics,
we use conventional macroscopic objects as guiding examples to clarify the
content of two important results of the beginning of twentieth century:
Einstein-Podolsky-Rosen's reality criterion and Heisenberg's uncertainty
principle. We then use them in combination to show that our widespread belief
in the existence of microscopic particles is only the result of a cognitive
illusion, as microscopic particles are not particles, but are instead the
ephemeral spatial and local manifestations of non-spatial and non-local
entities
Magneto-asteroseismology of massive magnetic pulsators
Simultaneously and coherently studying the large-scale magnetic field and the
stellar pulsations of a massive star provides strong complementary diagnostics
suitable for detailed stellar modelling. This hybrid method is called
magneto-asteroseismology and permits the determination of the internal
structure and conditions within magnetic massive pulsators, for example the
effect of magnetism on non-standard mixing processes. Here, we overview this
technique, its requirements, and list the currently known suitable stars to
apply the method.Comment: 5 pages, 1 table, IAUS 329 conference proceeding
Observational signatures of convectively driven waves in massive stars
We demonstrate observational evidence for the occurrence of convectively
driven internal gravity waves (IGW) in young massive O-type stars observed with
high-precision CoRoT space photometry. This evidence results from a comparison
between velocity spectra based on 2D hydrodynamical simulations of IGW in a
differentially-rotating massive star and the observed spectra.We also show that
the velocity spectra caused by IGW may lead to detectable line-profile
variability and explain the occurrence of macroturbulence in the observed line
profiles of OB stars. Our findings provide predictions that can readily be
tested by including a sample of bright slowly and rapidly rotating OB-type
stars in the scientific programme of the K2 mission accompanied by
high-precision spectroscopy and their confrontation with multi-dimensional
hydrodynamic simulations of IGW for various masses and ages.Comment: 4 pages, 3 figures, accepted for publication in The Astrophysical
Journal Letter
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