234 research outputs found
Properties of Physical Systems: Transient Singularities on Borders and Surface Transitive Zones
Certain alternative properties of physical systems are describable by
supports of arguments of response functions (e.g. light cone, borders of media)
and expressed by projectors; corresponding equations of restraints lead to
dispersion relations, theorems of counting, etc. As supports are measurable,
their absolutely strict borders contradict the spirit of quantum theory and
their quantum evolution leading to appearance of subtractions or certain needed
flattening would be considered. Flattening of projectors introduce transitive
zones that can be examined as a specification of adiabatic hypothesis or the
Bogoliubov regulatory function in QED. For demonstration of their possibilities
the phenomena of refraction and reflection of electromagnetic wave are
considered; they show, in particular, the inevitable appearing of double
electromagnetic layers on all surfaces that formerly were repeatedly
postulated, etc. Quantum dynamics of projectors proves the neediness of
subtractions that usually are artificially adding and express transient
singularities and zones in squeezed forms.Comment: 12 p
The Physical Principles of Quantum Mechanics. A critical review
The standard presentation of the principles of quantum mechanics is
critically reviewed both from the experimental/operational point and with
respect to the request of mathematical consistency and logical economy. A
simpler and more physically motivated formulation is discussed. The existence
of non commuting observables, which characterizes quantum mechanics with
respect to classical mechanics, is related to operationally testable
complementarity relations, rather than to uncertainty relations. The drawbacks
of Dirac argument for canonical quantization are avoided by a more geometrical
approach.Comment: Bibliography and section 2.1 slightly improve
Centre-of-mass separation in quantum mechanics: Implications for the many-body treatment in quantum chemistry and solid state physics
We address the question to what extent the centre-of-mass (COM) separation
can change our view of the many-body problem in quantum chemistry and solid
state physics. It was shown that the many-body treatment based on the
electron-vibrational Hamiltonian is fundamentally inconsistent with the
Born-Handy ansatz so that such a treatment can never respect the COM problem.
Born-Oppenheimer (B-O) approximation reveals some secret: it is a limit case
where the degrees of freedom can be treated in a classical way. Beyond the B-O
approximation they are inseparable in principle. The unique covariant
description of all equations with respect to individual degrees of freedom
leads to new types of interaction: besides the known vibronic (electron-phonon)
one the rotonic (electron-roton) and translonic (electron-translon)
interactions arise. We have proved that due to the COM problem only the
hypervibrations (hyperphonons, i.e. phonons + rotons + translons) have true
physical meaning in molecules and crystals; nevertheless, the use of pure
vibrations (phonons) is justified only in the adiabatic systems. This fact
calls for the total revision of our contemporary knowledge of all non-adiabatic
effects, especially the Jahn-Teller effect and superconductivity. The vibronic
coupling is responsible only for removing of electron (quasi)degeneracies but
for the explanation of symmetry breaking and forming of structure the rotonic
and translonic coupling is necessary.Comment: 39 pages, 11 sections, 3 appendice
Facts, Values and Quanta
Quantum mechanics is a fundamentally probabilistic theory (at least so far as
the empirical predictions are concerned). It follows that, if one wants to
properly understand quantum mechanics, it is essential to clearly understand
the meaning of probability statements. The interpretation of probability has
excited nearly as much philosophical controversy as the interpretation of
quantum mechanics. 20th century physicists have mostly adopted a frequentist
conception. In this paper it is argued that we ought, instead, to adopt a
logical or Bayesian conception. The paper includes a comparison of the orthodox
and Bayesian theories of statistical inference. It concludes with a few remarks
concerning the implications for the concept of physical reality.Comment: 30 pages, AMS Late
Quantum value indefiniteness
The indeterministic outcome of a measurement of an individual quantum is
certified by the impossibility of the simultaneous, definite, deterministic
pre-existence of all conceivable observables from physical conditions of that
quantum alone. We discuss possible interpretations and consequences for quantum
oracles.Comment: 19 pages, 2 tables, 2 figures; contribution to PC0
A new interferometric study of four exoplanet host stars : {\theta} Cygni, 14 Andromedae, {\upsilon} Andromedae and 42 Draconis
Studying exoplanet host stars is of the utmost importance to establish the
link between the presence of exoplanets around various types of stars and to
understand the respective evolution of stars and exoplanets.
Using the limb-darkened diameter (LDD) obtained from interferometric data, we
determine the fundamental parameters of four exoplanet host stars. We are
particularly interested in the F4 main-sequence star, {\theta} Cyg, for which
Kepler has recently revealed solar-like oscillations that are unexpected for
this type of star. Furthermore, recent photometric and spectroscopic
measurements with SOPHIE and ELODIE (OHP) show evidence of a quasi-periodic
radial velocity of \sim150 days. Models of this periodic change in radial
velocity predict either a complex planetary system orbiting the star, or a new
and unidentified stellar pulsation mode.
We performed interferometric observations of {\theta} Cyg, 14 Andromedae,
{\upsilon} Andromedae and 42 Draconis for two years with VEGA/CHARA (Mount
Wilson, California) in several three-telescope configurations. We measured
accurate limb darkened diameters and derived their radius, mass and temperature
using empirical laws.
We obtain new accurate fundamental parameters for stars 14 And, {\upsilon}
And and 42 Dra. We also obtained limb darkened diameters with a minimum
precision of \sim 1.3%, leading to minimum planet masses of Msini=5.33\pm 0.57,
0.62 \pm 0.09 and 3.79\pm0.29 MJup for 14 And b, {\upsilon} And b and 42 Dra b,
respectively. The interferometric measurements of {\theta} Cyg show a
significant diameter variability that remains unexplained up to now. We propose
that the presence of these discrepancies in the interferometric data is caused
by either an intrinsic variation of the star or an unknown close companion
orbiting around it.Comment: 10 pages + 2 pages appendix, 16 figures, accepted for publication in
A&
Inversion of Randomly Corrugated Surfaces Structure from Atom Scattering Data
The Sudden Approximation is applied to invert structural data on randomly
corrugated surfaces from inert atom scattering intensities. Several expressions
relating experimental observables to surface statistical features are derived.
The results suggest that atom (and in particular He) scattering can be used
profitably to study hitherto unexplored forms of complex surface disorder.Comment: 10 pages, no figures. Related papers available at
http://neon.cchem.berkeley.edu/~dan
Peak positions and shapes in neutron pair correlation functions from powders of highly anisotropic crystals
The effect of the powder average on the peak shapes and positions in neutron
pair distribution functions of polycrystalline materials is examined. It is
shown that for highly anisotropic crystals, the powder average leads to shifts
in peak positions and to non-Gaussian peak shapes. The peak shifts can be as
large as several percent of the lattice spacing
Theory and Applications of X-ray Standing Waves in Real Crystals
Theoretical aspects of x-ray standing wave method for investigation of the
real structure of crystals are considered in this review paper. Starting from
the general approach of the secondary radiation yield from deformed crystals
this theory is applied to different concreat cases. Various models of deformed
crystals like: bicrystal model, multilayer model, crystals with extended
deformation field are considered in detailes. Peculiarities of x-ray standing
wave behavior in different scattering geometries (Bragg, Laue) are analysed in
detailes. New possibilities to solve the phase problem with x-ray standing wave
method are discussed in the review. General theoretical approaches are
illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table
Relational Quantum Mechanics
I suggest that the common unease with taking quantum mechanics as a
fundamental description of nature (the "measurement problem") could derive from
the use of an incorrect notion, as the unease with the Lorentz transformations
before Einstein derived from the notion of observer-independent time. I suggest
that this incorrect notion is the notion of observer-independent state of a
system (or observer-independent values of physical quantities). I reformulate
the problem of the "interpretation of quantum mechanics" as the problem of
deriving the formalism from a few simple physical postulates. I consider a
reformulation of quantum mechanics in terms of information theory. All systems
are assumed to be equivalent, there is no observer-observed distinction, and
the theory describes only the information that systems have about each other;
nevertheless, the theory is complete.Comment: Substantially revised version. LaTeX fil
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