27,566 research outputs found
Anvil or Onion? Determinism as a Layered Concept
Stephen Kellert (1993) has argued that Laplacean determinism in classical physics is actually a layered concept, where various properties or layers composing this form of determinism can be peeled away. Here, I argue that a layered conception of determinism is inappropriate and that we should think in terms of different deterministic models applicable to different kinds of systems. The upshot of this analysis is that the notion of state is more closely tied to the kind of system being investigated than is usually considered in discussions of determinism. So when investigating determinism corresponding changes to the appropriate notion of stateâand, perhaps, the state space itselfâalso need to be considered
The Hidden Premise in the Causal Argument for Physicalism
The causal argument for physicalism is anayzed and it's key premise--the causal closure of physics--is found wanting. Therefore, a hidden premise must be added to the argument to gain its conclusion, but the hidden premise is indistinguishable from the conclusion of the causal argument. Therefore, it begs the question on physicalism
Quantum Time Arrows, Semigroups and Time-Reversal in Scattering
Two approaches toward the arrow of time for scattering processes have been proposed in rigged Hilbert space quantum mechanics. One, due to Arno Bohm, involves preparations and registrations in laboratory operations and results in two semigroups oriented in the forward direction of time. The other, employed by the Brussels-Austin group, is more general, involving excitations and de-excitations of systems, and apparently results in two semigroups oriented in opposite directions of time. It turns out that these two time arrows can be related to each other via Wigner's extensions of the spacetime symmetry group. Furthermore, their are subtle differences in causality as well as the possibilities for the existence and creation of time-reversed states depending on which time arrow is chose
Brussels-Austin Nonequilibrium Statistical Mechanics in the Early Years: Similarity Transformations between Deterministic and Probabilistic Descriptions
The fundamental problem on which Ilya Prigogine and the Brussels-Austin Group
have focused can be stated briefly as follows. Our observations indicate that
there is an arrow of time in our experience of the world (e.g., decay of
unstable radioactive atoms like Uranium, or the mixing of cream in coffee).
Most of the fundamental equations of physics are time reversible, however,
presenting an apparent conflict between our theoretical descriptions and
experimental observations. Many have thought that the observed arrow of time
was either an artifact of our observations or due to very special initial
conditions. An alternative approach, followed by the Brussels-Austin Group, is
to consider the observed direction of time to be a basics physical phenomenon
and to develop a mathematical formalism that can describe this direction as
being due to the dynamics of physical systems. In part I of this essay, I
review and assess an attempt to carry out an approach that received much of
their attention from the early 1970s to the mid 1980s. In part II, I will
discuss their more recent approach using rigged Hilbert spaces.Comment: 22 pages, Part I of two parts; updated institutional affiliatio
Humidity resistant solar cell contacts
Gold-platinum solar cell contact is developed which does not exhibit chemical reactivity of titanium or porosity of silver. This contact offers excellent ohmic characteristics and stability in humid air
The Value-of-Information in Matching with Queues
We consider the problem of \emph{optimal matching with queues} in dynamic
systems and investigate the value-of-information. In such systems, the
operators match tasks and resources stored in queues, with the objective of
maximizing the system utility of the matching reward profile, minus the average
matching cost. This problem appears in many practical systems and the main
challenges are the no-underflow constraints, and the lack of matching-reward
information and system dynamics statistics. We develop two online matching
algorithms: Learning-aided Reward optimAl Matching () and
Dual- () to effectively resolve both challenges.
Both algorithms are equipped with a learning module for estimating the
matching-reward information, while incorporates an additional
module for learning the system dynamics. We show that both algorithms achieve
an close-to-optimal utility performance for any
, while achieves a faster convergence speed and a
better delay compared to , i.e., delay and convergence under
compared to delay and convergence under
( and are maximum estimation errors for
reward and system dynamics). Our results reveal that information of different
system components can play very different roles in algorithm performance and
provide a systematic way for designing joint learning-control algorithms for
dynamic systems
The Economic Effects in 2002 of Chronic Wasting Disease (CWD) in Wisconsin
Wisconsin's 600,000 deer hunters will bear the brunt of the economic losses from chronic wasting disease (CWD) in the Wisconsin deer herd. Though studies have not been done to pinpoint a precise value, preliminary estimates place the losses to deer hunters at between 100 million this fall. CWD will also cause deer hunters to spend less on their sport this year than they have in the past. However, the impacts of reduced hunter spending on the Wisconsin economy should not be too large. Losses to the deer hunting economy will be counterbalanced as resident hunters spend their money elsewhere in the economy. Some spending by nonresident hunters will be lost, but deer hunting is a very small part of the tourist economy. Nevertheless, some people in rural areas will suffer economically as fewer urban deer hunters spend money on the services they provide. If additional bad news about CWD is forthcoming before fall, the losses could be much larger.
- âŚ