580 research outputs found
Quantum Criticality and the Alpha/Delta Puzzle
In this paper we suggest a novel explanation for the alpha-delta transition
in plutonium based on an analogy between the evolution of the actinide ground
state as a function of spin orbit coupling and the behaviour of thin film
superconductors in a magnetic field. The key point is that in metals with a low
carrier density spin-orbit interactions give rise to low energy monopole-like
solitons with quantized spin currents, which play much the same role as
Abrikosov vortices in thin film superconductors. In alpha-plutonium these
solitons form an ordered solid, while in impurity stabilized delta-plutonium
they form a pair condensate.Comment: 7 pages, 1 figur
A Unique Theory of Gravity and Matter
The author has previously suggested that the ground state for 4-dimensional
quantum gravity can be represented as a condensation of non-linear gravitons
connected by Dirac strings. In this note we suggest that the low-lying
excitations of this state can be described by a quasi-topological action
corresponding to a trilinear coupling of solitonic 8-branes and 7-branes. It is
shown that when the 7-brane excitations are neglected, the effective action can
be interpreted as a theory of conformal gravity in four dimensions. This
suggests that ordinary gravity as well as supersymmetric matter and
phenomenological gauge symmetries arise from the spontaneous breaking of
topological invariance.Comment: PostScript, 12 page
Dark Energy Stars and AdS/CFT
The theory of dark energy stars illustrates how the behavior of matter near
to certain kinds of quantum critical phase transitions can be given a
geometrical interpretation by regarding the criticality tuning parameter as an
extra dimension. In the case of a superfluid with vanishing speed of sound, the
implied geometry resembles 5-dimensional anti-de-Sitter. In a dark energy star
this geometry applies both inside and outside the horizon radius, so the
AdS-CFT correspondence is consistent with the idea that the surface of a
compact astrophysical object represents a quantum critical phase transition of
space-time. The superfluid transition in a chiron gas, which was originally
proposed as a theory of high temperature superconductivity, may provide an
exact theory of this transition.Comment: Talk at the 12th Marcel Grossman Meetin
Transition from Quantum to Classical Information in a Superfluid
Whereas the entropy of any deterministic classical system described by a
principle of least action is zero, one can assign a "quantum information" to
quantum mechanical degree of freedom equal to Hausdorff area of the deviation
from a classical path. This raises the question whether superfluids carry
quantum information. We show that in general the transition from the classical
to quantum behavior depends on the probing length scale, and occurs for
microscopic length scales, except when the interactions between the particles
are very weak. This transition explains why, on macroscopic length scales,
physics is described by classical equations.Comment: 11 pages, 4 figure
Minimum Energy Information Fusion in Sensor Networks
In this paper we consider how to organize the sharing of information in a
distributed network of sensors and data processors so as to provide
explanations for sensor readings with minimal expenditure of energy. We point
out that the Minimum Description Length principle provides an approach to
information fusion that is more naturally suited to energy minimization than
traditional Bayesian approaches. In addition we show that for networks
consisting of a large number of identical sensors Kohonen self-organization
provides an exact solution to the problem of combining the sensor outputs into
minimal description length explanations.Comment: postscript, 8 pages. Paper 65 in Proceedings of The 2nd International
Conference on Information Fusio
Sentient Networks
In this paper we consider the question whether a distributed network of
sensors and data processors can form "perceptions" based on the sensory data.
Because sensory data can have exponentially many explanations, the use of a
central data processor to analyze the outputs from a large ensemble of sensors
will in general introduce unacceptable latencies for responding to dangerous
situations. A better idea is to use a distributed "Helmholtz machine"
architecture in which the collective state of the network as a whole provides
an explanation for the sensory data.Comment: PostScript, 14 page
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