12,280 research outputs found
A Way Out of the Quantum Trap
We review Event Enhanced Quantum Theory (EEQT). In Section 1 we address the
question "Is Quantum Theory the Last Word". In particular we respond to some of
recent challenging staments of H.P. Stapp. We also discuss a possible future of
the quantum paradigm - see also Section 5. In Section 2 we give a short sketch
of EEQT. Examples are given in Section 3. Section 3.3 discusses a completely
new phenomenon - chaos and fractal-like phenomena caused by a simultaneous
"measurement" of several non-commuting observables (we include picture of
Barnsley's IFS on unit sphere of a Hilbert space). In Section 4 we answer
"Frequently Asked Questions" concerning EEQT.Comment: Replacement. Corrected affiliation. Latex, one .jpg figure. To appear
in Proc. Conf. Relativistic Quantum Measurements, Napoli 1998, Ed. F.
Petruccion
On the existence of effective potentials in time-dependent density functional theory
We investigate the existence and properties of effective potentials in
time-dependent density functional theory. We outline conditions for a general
solution of the corresponding Sturm-Liouville boundary value problems. We
define the set of potentials and v-representable densities, give a proof of
existence of the effective potentials under certain restrictions, and show the
set of v-representable densities to be independent of the interaction.Comment: 13 page
Thermodynamic versus Topological Phase Transitions: Cusp in the Kert\'esz Line
We present a study of phase transitions of the Curie--Weiss Potts model at
(inverse) temperature , in presence of an external field . Both
thermodynamic and topological aspects of these transitions are considered. For
the first aspect we complement previous results and give an explicit equation
of the thermodynamic transition line in the -- plane as well as the
magnitude of the jump of the magnetization (for . The signature
of the latter aspect is characterized here by the presence or not of a giant
component in the clusters of a Fortuin--Kasteleyn type representation of the
model. We give the equation of the Kert\'esz line separating (in the
-- plane) the two behaviours. As a result, we get that this line
exhibits, as soon as , a very interesting cusp where it
separates from the thermodynamic transition line
Preliminary results of penetrator field test program, Tonopah, Nevada, 16-28 April 1979
Subscale (0.63 scale) penetrators impacted various sizes of volcanic rocks resting on and within compacted plays sediments. All penetrators were identical in size, shape, weight, and impact velocity. Although minor variations in impact angle were documented, the final orientation of the buried penetrators was primarily a consequence of the size, shape, and depth of the rocks encountered during impact. In situ measurements of impacted penetrators revealed that surface and buried layers of rocks having diameters up to 3 times the penetrator diameter caused only small ( 10 deg) angles of deflection. Only large single rocks greater than 10 times the penetrator diameter caused deflections appreciably greater than 10 deg. The large deflection angles followed by the penetrator were strongly influenced by fracture planes that developed in the rock as it broke apart. No catastrophic failure of the penetrator occurred during these tests. A cross section of the path of each penetrator through the ground is shown together with details on orientation before, during, and after the tests. Comparisons are made with results of previous subscale penetrator tests, and conclusions are drawn with respect to full-scale Mars penetrator performance
SCD Patterns Have Singular Diffraction
Among the many families of nonperiodic tilings known so far, SCD tilings are
still a bit mysterious. Here, we determine the diffraction spectra of point
sets derived from SCD tilings and show that they have no absolutely continuous
part, that they have a uniformly discrete pure point part on the z-axis, and
that they are otherwise supported on a set of concentric cylinder surfaces
around this axis. For SCD tilings with additional properties, more detailed
results are given.Comment: 11 pages, 2 figures; Accepted for Journal of Mathematical Physic
Noncommutative geometry and stochastic processes
The recent analysis on noncommutative geometry, showing quantization of the
volume for the Riemannian manifold entering the geometry, can support a view of
quantum mechanics as arising by a stochastic process on it. A class of
stochastic processes can be devised, arising as fractional powers of an
ordinary Wiener process, that reproduce in a proper way a stochastic process on
a noncommutative geometry. These processes are characterized by producing
complex values and so, the corresponding Fokker-Planck equation resembles the
Schroedinger equation. Indeed, by a direct numerical check, one can recover the
kernel of the Schroedinger equation starting by an ordinary Brownian motion.
This class of stochastic processes needs a Clifford algebra to exist. In four
dimensions, the full set of Dirac matrices is needed and the corresponding
stochastic process in a noncommutative geometry is easily recovered as is the
Dirac equation in the Klein-Gordon form being it the Fokker--Planck equation of
the process.Comment: 16 pages, 2 figures. Updated a reference. A version of this paper
will appear in the proceedings of GSI2017, Geometric Science of Information,
November 7th to 9th, Paris (France
Biochemical and physiological evaluation of human subjects in a life support systems evaluator
Biochemical and physiological evaluation of human nutritional requirements under simulated aerospace condition
Surface penetrators for planetary exploration: Science rationale and development program
Work on penetrators for planetary exploration is summarized. In particular, potential missions, including those to Mars, Mercury, the Galilean satellites, comets, and asteroids are described. A baseline penetrator design for the Mars mission is included, as well as potential instruments and their status in development. Penetration tests in soft soil and basalt to study material eroded from the penetrator; changes in the structure, composition, and physical properties of the impacted soil; seismic coupling; and penetrator deflection caused by impacting rocks, are described. Results of subsystem studies and tests are given for design of entry decelerators, high-g components, thermal control, data acquisition, and umbilical cable deployment
On Quantum Jumps, Events and Spontaneous Localization Models
We propose a definite meaning to the concepts of "experiment", "measurement"
and "event" in the event-enhanced formalism of quantum theory. A minimal
piecewise deterministic process is given that can be used for a computer
simulation of real time series of experiments on single quantum objects. As an
example a generalized cloud chamber is described, including multiparticle case.
Relation to the GRW spontaneous localization model is discussed. The second
revised version of the paper contains references to papers by other authors
that are are aiming in the same direction: to enhance quantum theory in such a
way that it will provide stochastic description of events triggered by
individual quantum systems.Comment: 20 page
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