3,518 research outputs found
What is Quantum? Unifying Its Micro-Physical and Structural Appearance
We can recognize two modes in which 'quantum appears' in macro domains: (i) a
'micro-physical appearance', where quantum laws are assumed to be universal and
they are transferred from the micro to the macro level if suitable 'quantum
coherence' conditions (e.g., very low temperatures) are realized, (ii) a
'structural appearance', where no hypothesis is made on the validity of quantum
laws at a micro level, while genuine quantum aspects are detected at a
structural-modeling level. In this paper, we inquire into the connections
between the two appearances. We put forward the explanatory hypothesis that,
'the appearance of quantum in both cases' is due to 'the existence of a
specific form of organisation, which has the capacity to cope with random
perturbations that would destroy this organisation when not coped with'. We
analyse how 'organisation of matter', 'organisation of life', and 'organisation
of culture', play this role each in their specific domain of application, point
out the importance of evolution in this respect, and put forward how our
analysis sheds new light on 'what quantum is'.Comment: 10 page
Estimating stellar oscillation-related parameters and their uncertainties with the moment method
The moment method is a well known mode identification technique in
asteroseismology (where `mode' is to be understood in an astronomical rather
than in a statistical sense), which uses a time series of the first 3 moments
of a spectral line to estimate the discrete oscillation mode parameters l and
m. The method, contrary to many other mode identification techniques, also
provides estimates of other important continuous parameters such as the
inclination angle alpha, and the rotational velocity v_e. We developed a
statistical formalism for the moment method based on so-called generalized
estimating equations (GEE). This formalism allows the estimation of the
uncertainty of the continuous parameters taking into account that the different
moments of a line profile are correlated and that the uncertainty of the
observed moments also depends on the model parameters. Furthermore, we set up a
procedure to take into account the mode uncertainty, i.e., the fact that often
several modes (l,m) can adequately describe the data. We also introduce a new
lack of fit function which works at least as well as a previous discriminant
function, and which in addition allows us to identify the sign of the azimuthal
order m. We applied our method to the star HD181558, using several numerical
methods, from which we learned that numerically solving the estimating
equations is an intensive task. We report on the numerical results, from which
we gain insight in the statistical uncertainties of the physical parameters
involved in the moment method.Comment: The electronic online version from the publisher can be found at
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-9876.2005.00487.
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
Experimental Evidence for Quantum Structure in Cognition
We proof a theorem that shows that a collection of experimental data of
membership weights of items with respect to a pair of concepts and its
conjunction cannot be modeled within a classical measure theoretic weight
structure in case the experimental data contain the effect called
overextension. Since the effect of overextension, analogue to the well-known
guppy effect for concept combinations, is abundant in all experiments testing
weights of items with respect to pairs of concepts and their conjunctions, our
theorem constitutes a no-go theorem for classical measure structure for common
data of membership weights of items with respect to concepts and their
combinations. We put forward a simple geometric criterion that reveals the non
classicality of the membership weight structure and use experimentally measured
membership weights estimated by subjects in experiments to illustrate our
geometrical criterion. The violation of the classical weight structure is
similar to the violation of the well-known Bell inequalities studied in quantum
mechanics, and hence suggests that the quantum formalism and hence the modeling
by quantum membership weights can accomplish what classical membership weights
cannot do.Comment: 12 pages, 3 figure
Cartoon Computation: Quantum-like computing without quantum mechanics
We present a computational framework based on geometric structures. No
quantum mechanics is involved, and yet the algorithms perform tasks analogous
to quantum computation. Tensor products and entangled states are not needed --
they are replaced by sets of basic shapes. To test the formalism we solve in
geometric terms the Deutsch-Jozsa problem, historically the first example that
demonstrated the potential power of quantum computation. Each step of the
algorithm has a clear geometric interpetation and allows for a cartoon
representation.Comment: version accepted in J. Phys.A (Letter to the Editor
Ground-based observations of the beta Cephei CoRoT main target HD 180642: abundance analysis and mode identification
The known beta Cephei star HD 180642 was observed by the CoRoT satellite in
2007. From the very high-precision light curve, its pulsation frequency
spectrum could be derived for the first time (Degroote and collaborators). In
this paper, we obtain additional constraints for forthcoming asteroseismic
modeling of the target. Our results are based on both extensive ground-based
multicolour photometry and high-resolution spectroscopy. We determine T_eff =
24 500+-1000 K and log g = 3.45+-0.15 dex from spectroscopy. The derived
chemical abundances are consistent with those for B stars in the solar
neighbourhood, except for a mild nitrogen excess. A metallicity Z =
0.0099+-0.0016 is obtained. Three modes are detected in photometry. The degree
l is unambiguously identified for two of them: l = 0 and l = 3 for the
frequencies 5.48694 1/d and 0.30818 1/d, respectively. The radial mode is
non-linear and highly dominant with an amplitude in the U-filter about 15 times
larger than the strongest of the other modes. For the third frequency of
7.36673 1/d found in photometry, two possibilities remain: l = 0 or 3. In the
radial velocities, the dominant radial mode presents a so-called stillstand but
no clear evidence of the existence of shocks is observed. Four low-amplitude
modes are found in spectroscopy and one of them, with frequency 8.4079 1/d, is
identified as (l,m)=(3,2). Based on this mode identification, we finally deduce
an equatorial rotational velocity of 38+-15 km/s.Comment: Accepted for publication in Astronomy and Astrophysic
Pulsations detected in the line profile variations of red giants: Modelling of line moments, line bisector and line shape
Contents: So far, red giant oscillations have been studied from radial
velocity and/or light curve variations, which reveal frequencies of the
oscillation modes. To characterise radial and non-radial oscillations, line
profile variations are a valuable diagnostic. Here we present for the first
time a line profile analysis of pulsating red giants, taking into account the
small line profile variations and the predicted short damping and re-excitation
times. We do so by modelling the time variations in the cross correlation
profiles in terms of oscillation theory.
Aims: The performance of existing diagnostics for mode identification is
investigated for known oscillating giants which have very small line profile
variations. We modify these diagnostics, perform simulations, and characterise
the radial and non-radial modes detected in the cross correlation profiles.
Methods: Moments and line bisectors are computed and analysed for four
giants. The robustness of the discriminant of the moments against small
oscillations with finite lifetimes is investigated. In addition, line profiles
are simulated with short damping and re-excitation times and their line shapes
are compared with the observations.
Results: For three stars, we find evidence for the presence of non-radial
pulsation modes, while for Hydrae perhaps only radial modes are present.
Furthermore the line bisectors are not able to distinguish between different
pulsation modes and are an insufficient diagnostic to discriminate small line
profile variations due to oscillations from exoplanet motion.Comment: 12 pages, 10 figures, accepted by A&
Close-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observations
To optimise the science results of the asteroseismic part of the CoRoT
satellite mission a complementary simultaneous ground-based observational
campaign is organised for selected CoRoT targets. The observations include both
high-resolution spectroscopic and multi-colour photometric data. We present the
preliminary results of the analysis of the ground-based observations of three
targets. A line-profile analysis of 216 high-resolution FEROS spectra of the
delta Sct star HD 50844 reveals more than ten pulsation frequencies in the
frequency range 5-18 c/d, including possibly one radial fundamental mode (6.92
c/d). Based on more than 600 multi-colour photometric datapoints of the beta
Cep star HD180642, spanning about three years and obtained with different
telescopes and different instruments, we confirm the presence of a dominant
radial mode nu1=5.48695 c/d, and detect also its first two harmonics. We find
evidence for a second mode nu2=0.3017 c/d, possibly a g-mode, and indications
for two more frequencies in the 7-8 c/d domain. From Stromgren photometry we
find evidence for the hybrid delta Sct/gamma Dor character of the F0 star HD
44195, as frequencies near 3 c/d and 21 c/d are detected simultaneously in the
different filters.Comment: 7 pages, 6 figures, HELAS II International Conference
"Helioseismology, Asteroseismology and MHD Connections", 2008, J.Phys.: Conf.
Ser. 118, 01207
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