6,025 research outputs found
On the Electromagnetic Properties of Matter in Collapse Models
We discuss the electromagnetic properties of both a charged free particle,
and a charged particle bounded by an harmonic potential, within collapse
models. By choosing a particularly simple, yet physically relevant, collapse
model, and under only the dipole approximation, we are able to solve the
equation of motion exactly. In this way, both the finite time and large time
behavior can be analyzed accurately. We discovered new features, which did not
appear in previous works on the same subject. Since, so far, the spontaneous
photon emission process places the strongest upper bounds on the collapse
parameters, our results call for a further analysis of this process for those
atomic systems which can be employed in experimental tests of collapse models,
as well as of quantum mechanics.Comment: 17 pages, LaTeX, updated version with minor change
Cosmogenesis and Collapse
Some possible benefits of dynamical collapse for a quantum theory of
cosmogenesis are discussed. These are a possible long wait before creation
begins, creation of energy and space, and choice of a particular universe out
of a superposition.Comment: For a festschrift in Foundations of Physics in honor of Daniel
Greenberger and Helmut Rauch in Foundations of Physics. This updates the
previous version by adding an appendix (Appendix B) which contains the exact
solution of a partial differential equation of importance in the pape
Dynamical Reduction Models: present status and future developments
We review the major achievements of the dynamical reduction program, showing
why and how it provides a unified, consistent description of physical
phenomena, from the microscopic quantum domain to the macroscopic classical
one. We discuss the difficulties in generalizing the existing models in order
to comprise also relativistic quantum field theories. We point out possible
future lines of research, ranging from mathematical physics to phenomenology.Comment: 12 pages. Contribution to the Proceedings of the "Third International
Workshop DICE2006", Castello di Piombino (Tuscany), September 11-15, 2006.
Minor changes mad
The Hilbert space operator formalism within dynamical reduction models
Unlike standard quantum mechanics, dynamical reduction models assign no
particular a priori status to `measurement processes', `apparata', and
`observables', nor self-adjoint operators and positive operator valued measures
enter the postulates defining these models. In this paper, we show why and how
the Hilbert-space operator formalism, which standard quantum mechanics
postulates, can be derived from the fundamental evolution equation of dynamical
reduction models. Far from having any special ontological meaning, we show that
within the dynamical reduction context the operator formalism is just a compact
and convenient way to express the statistical properties of the outcomes of
experiments.Comment: 25 pages, RevTeX. Changes made and two figures adde
Wells and ill-fare: impacts of well failures on cultivators in hard rock areas of Madhya Pradesh
WellsDrillingCostsGroundwater depletionWater tableGroundwater irrigationOwnershipEconomic impactSocial impactCrop managementFood security
The quantum theory of measurement within dynamical reduction models
We analyze in mathematical detail, within the framework of the QMUPL model of
spontaneous wave function collapse, the von Neumann measurement scheme for the
measurement of a 1/2 spin particle. We prove that, according to the equation of
the model: i) throughout the whole measurement process, the pointer of the
measuring device is always perfectly well localized in space; ii) the
probabilities for the possible outcomes are distributed in agreement with the
Born probability rule; iii) at the end of the measurement the state of the
microscopic system has collapsed to the eigenstate corresponding to the
measured eigenvalue. This analysis shows rigorously how dynamical reduction
models provide a consistent solution to the measurement problem of quantum
mechanics.Comment: 24 pages, RevTeX. Minor changes mad
Low latitude middle atmosphere ionization studies
Low latitude middle atmosphere ionization was studied with data obtained from three blunt conductivity probes and one Gerdien condenser. An investigation was conducted into the effects of various ionization sources in the 40 to 65 Km altitude range. An observed enhancement of positive ion conductivity taking place during the night can be explained by an atmsopheric effect, with cosmic rays being the only source of ionization only if the ion-ion recombination coefficient (alpha sub i) is small(10 to the -7 power cu cm/s) and varies greatly with altitude. More generally accepted values of alpha sub i ( approximately equal to 3x10 to the -7 power cu cm/s) require an additional source of ionization peaking at about 65 Km, and corresponding approximately to the integrated effect of an X-ray flux measured on a rocket flown in conjunction with the ionization measurements. The reasonable assumption of an alpha sub i which does not vary with altitude in the 50-70 Km range implies an even greater value alpha sub i and a more intense and harder X-ray spectrum
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