2,939,611 research outputs found
Topological Field Theory Interpretation of String Topology
The string bracket introduced by Chas and Sullivan [math.GT/9911159] is
reinterpreted from the point of view of topological field theories in the
Batalin-Vilkovisky or BRST formalisms. Namely, topological action functionals
for gauge fields (generalizing Chern-Simons and BF theories) are considered
together with generalized Wilson loops. The latter generate a (Poisson or
Gerstenhaber) algebra of functionals with values in the -equivariant
cohomology of the loop space of the manifold on which the theory is defined. It
is proved that, in the case of with standard representation, the
(Poisson or BV) bracket of two generalized Wilson loops applied to two cycles
is the same as the generalized Wilson loop applied to the string bracket of the
cycles. Generalizations to other groups are briefly described.Comment: 27 pages, 2 figure
The Minimal Modal Interpretation of Quantum Theory
We introduce a realist, unextravagant interpretation of quantum theory that
builds on the existing physical structure of the theory and allows experiments
to have definite outcomes, but leaves the theory's basic dynamical content
essentially intact. Much as classical systems have specific states that evolve
along definite trajectories through configuration spaces, the traditional
formulation of quantum theory asserts that closed quantum systems have specific
states that evolve unitarily along definite trajectories through Hilbert
spaces, and our interpretation extends this intuitive picture of states and
Hilbert-space trajectories to the case of open quantum systems as well. We
provide independent justification for the partial-trace operation for density
matrices, reformulate wave-function collapse in terms of an underlying
interpolating dynamics, derive the Born rule from deeper principles, resolve
several open questions regarding ontological stability and dynamics, address a
number of familiar no-go theorems, and argue that our interpretation is
ultimately compatible with Lorentz invariance. Along the way, we also
investigate a number of unexplored features of quantum theory, including an
interesting geometrical structure---which we call subsystem space---that we
believe merits further study. We include an appendix that briefly reviews the
traditional Copenhagen interpretation and the measurement problem of quantum
theory, as well as the instrumentalist approach and a collection of
foundational theorems not otherwise discussed in the main text.Comment: 73 pages + references, 9 figures; cosmetic changes, added figure,
updated references, generalized conditional probabilities with attendant
changes to the sections on the EPR-Bohm thought experiment and Lorentz
invariance; for a concise summary, see the companion letter at
arXiv:1405.675
Can there ever be a theory of utterance interpretation?
In this paper, I tackle what appears to be a rather simple question: can there ever be a theory of utterance interpretation? It will be contended that a theory of utterance interpretation is not beyond the intellectual grasp of present-day pragmatists so much as it is a construct which lacks sense and is unintelligible. Although many of our most successful theories exhibit desiderata such as simplicity, completeness and explanatory power, it will be argued that these same desiderata are problematic when it is utterance interpretation that is the focus of theoretical efforts. The case in support of this claim sets out from a detailed analysis of the rational, intentional, holistic character of utterance interpretation and draws on the insights of the American philosopher Hilary Putnam. To the extent that a theory of utterance interpretation is not a difficult empirical possibility to realize so much as it is an endeavour which leads to an unintelligible outcome, we consider where this situation leaves pragmatists who have a substantial appetite for theory construction
The Modal Interpretation of Algebraic Quantum Field Theory
In a recent article, Dieks has proposed a way to implement the modal
interpretation of (nonrelativistic) quantum theory in relativistic quantum
field theory. We show that his proposal fails to yield a well-defined
prescription for which observables in a local spacetime region possess definite
values. On the other hand, we demonstrate that there is a well-defined and
unique way of extending the modal interpretation to the local algebras of
relativistic quantum field theory. This extension, however, faces a potentially
serious difficulty in connection with ergodic states of a field.Comment: 18 pages, LaTe
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