452 research outputs found

### 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

### Quasirelativistic quasilocal finite wave-function collapse model

A Markovian wave function collapse model is presented where the
collapse-inducing operator, constructed from quantum fields, is a manifestly
covariant generalization of the mass density operator utilized in the
nonrelativistic Continuous Spontaneous Localization (CSL) wave function
collapse model. However, the model is not Lorentz invariant because two such
operators do not commute at spacelike separation, i.e., the time-ordering
operation in one Lorentz frame, the "preferred" frame, is not the time-ordering
operation in another frame. However, the characteristic spacelike distance over
which the commutator decays is the particle's Compton wavelength so, since the
commutator rapidly gets quite small, the model is "almost" relativistic. This
"QRCSL" model is completely finite: unlike previous, relativistic, models, it
has no (infinite) energy production from the vacuum state.
QRCSL calculations are given of the collapse rate for a single free particle
in a superposition of spatially separated packets, and of the energy production
rate for any number of free particles: these reduce to the CSL rates if the
particle's Compton wavelength is small compared to the model's distance
parameter. One motivation for QRCSL is the realization that previous
relativistic models entail excitation of nuclear states which exceeds that of
experiment, whereas QRCSL does not: an example is given involving quadrupole
excitation of the $^{74}$Ge nucleus.Comment: 10 pages, to be published in Phys. Rev.

### How Stands Collapse II

I review ten problems associated with the dynamical wave function collapse
program, which were described in the first of these two papers. Five of these,
the \textit{interaction, preferred basis, trigger, symmetry} and
\textit{superluminal} problems, were discussed as resolved there. In this
volume in honor of Abner Shimony, I discuss the five remaining problems,
\textit{tails, conservation law, experimental, relativity, legitimization}.
Particular emphasis is given to the tails problem, first raised by Abner. The
discussion of legitimization contains a new argument, that the energy density
of the fluctuating field which causes collapse should exert a gravitational
force. This force can be repulsive, since this energy density can be negative.
Speculative illustrations of cosmological implications are offered.Comment: 37 page

### Relativistic state reduction model

In order to address the measurement problem of quantum theory we make the
assumption that quantum state reduction should be regarded as a genuine
physical process deserving of a dynamical description. Generalizing the
nonrelativistic spontaneous localization models of Ghirardi, Rimini, Weber, and
Pearle, a relativistic state reduction mechanism is proposed. The mechanism
involves nonlinear stochastic modifications to the standard description of
unitary state evolution and the introduction of a mediating field to facilitate
smearing of quantum field interactions.Comment: 7 pages, prepared for DICE2010 conference proceeding

### Relativistic state reduction dynamics

A mechanism describing state reduction dynamics in relativistic quantum field
theory is outlined. The mechanism involves nonlinear stochastic modifications
to the standard description of unitary state evolution and the introduction of
a relativistic field in which a quantized degree of freedom is associated to
each point in spacetime. The purpose of this field is to mediate in the
interaction between classical stochastic influences and conventional quantum
fields. The equations of motion are Lorentz covariant, frame independent, and
do not result in divergent behavior. It is shown that the mathematical
framework permits the specification of unambiguous local properties providing a
connection between the model and evidence of real world phenomena. The collapse
process is demonstrated for an idealized example.Comment: 20 pages, 2 figures, replacement with minor correction

### Relativistic formulation of quantum state diffusion?

The recently reported relativistic formulation of the well-known
non-relativistic quantum state diffusion is seriously mistaken. It predicts,
for instance, inconsistent measurement outcomes for the same system when seen
by two different inertial observers.Comment: 5 pages LaTeX, submitted to J. Phys.

### Collapse Models

This is a review of formalisms and models (nonrelativistic and relativistic)
which modify Schrodinger's equation so that it describes wavefunction collapse
as a dynamical physical process.Comment: 40 pages, to be published in "Open Systems and Measurement in
Relativistic Quantum Theory," F. Petruccione and H. P. Breuer eds. (Springer
Verlag, 1999

### Comment on "Finite Size Corrections to the Radiation Reaction Force in Classical Electrodynamics" [arXiv:1005.2617]

In [1, arXiv:1005.2617] effective field theory methods have been employed to
compute the equations of motion of a spherically symmetric charged shell of
radius R, taking into account the radiation reaction force exerted by the
shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have
stated that the known result for the self force of the shell as can be found
from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review
of Pearle [3]) is incorrect, in that the term linear in R should be absent. We
claim that this conclusion of Ref. [1] is incorrect, and that the textbook
result, Eq. (1) does hold.Comment: 1 pag

### On Spontaneous Wave Function Collapse and Quantum Field Theory

One way of obtaining a version of quantum mechanics without observers, and
thus of solving the paradoxes of quantum mechanics, is to modify the
Schroedinger evolution by implementing spontaneous collapses of the wave
function. An explicit model of this kind was proposed in 1986 by Ghirardi,
Rimini, and Weber (GRW), involving a nonlinear, stochastic evolution of the
wave function. We point out how, by focussing on the essential mathematical
structure of the GRW model and a clear ontology, it can be generalized to
(regularized) quantum field theories in a simple and natural way.Comment: 14 pages LaTeX, no figures; v2 minor improvement

### Dynamical state reduction in an EPR experiment

A model is developed to describe state reduction in an EPR experiment as a
continuous, relativistically-invariant, dynamical process. The system under
consideration consists of two entangled isospin particles each of which undergo
isospin measurements at spacelike separated locations. The equations of motion
take the form of stochastic differential equations. These equations are solved
explicitly in terms of random variables with a priori known probability
distribution in the physical probability measure. In the course of solving
these equations a correspondence is made between the state reduction process
and the problem of classical nonlinear filtering. It is shown that the solution
is covariant, violates Bell inequalities, and does not permit superluminal
signaling. It is demonstrated that the model is not governed by the Free Will
Theorem and it is argued that the claims of Conway and Kochen, that there can
be no relativistic theory providing a mechanism for state reduction, are false.Comment: 19 pages, 3 figure

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