A framework for the local information dynamics of distributed computation in complex systems

The nature of distributed computation has often been described in terms of the component operations of universal computation: information storage, transfer and modification. We review the first complete framework that quantifies each of these individual information dynamics on a local scale within a system, and describes the manner in which they interact to create non-trivial computation where "the whole is greater than the sum of the parts". We describe the application of the framework to cellular automata, a simple yet powerful model of distributed computation. This is an important application, because the framework is the first to provide quantitative evidence for several important conjectures about distributed computation in cellular automata: that blinkers embody information storage, particles are information transfer agents, and particle collisions are information modification events. The framework is also shown to contrast the computations conducted by several well-known cellular automata, highlighting the importance of information coherence in complex computation. The results reviewed here provide important quantitative insights into the fundamental nature of distributed computation and the dynamics of complex systems, as well as impetus for the framework to be applied to the analysis and design of other systems.Comment: 44 pages, 8 figure

Hadronic properties of the S_{11}(1535) studied by electroproduction off the deuteron

Properties of excited baryonic states are investigated in the context of electroproduction of baryon resonances off the deuteron. In particular, the hadronic radii and the compositeness of baryon resonances are studied for kinematic situations in which their hadronic reinteraction is the dominant contribution. Specifically, we study the reaction $d(e,e'S_{11})N$ at $Q^2\ge 1 GeV^2$ for kinematics in which the produced hadronic state reinteracts predominantly with the spectator nucleon. A comparison of constituent quark model and effective chiral Lagrangian calculations of the $S_{11}$ shows substantial sensitivity to the structure of the produced resonance.Comment: 24 pages, 5 figure

The Mathematical Universe

I explore physics implications of the External Reality Hypothesis (ERH) that there exists an external physical reality completely independent of us humans. I argue that with a sufficiently broad definition of mathematics, it implies the Mathematical Universe Hypothesis (MUH) that our physical world is an abstract mathematical structure. I discuss various implications of the ERH and MUH, ranging from standard physics topics like symmetries, irreducible representations, units, free parameters, randomness and initial conditions to broader issues like consciousness, parallel universes and Godel incompleteness. I hypothesize that only computable and decidable (in Godel's sense) structures exist, which alleviates the cosmological measure problem and help explain why our physical laws appear so simple. I also comment on the intimate relation between mathematical structures, computations, simulations and physical systems.Comment: Replaced to match accepted Found. Phys. version, 31 pages, 5 figs; more details at http://space.mit.edu/home/tegmark/toe.htm

Flammability and the heat of combustion of natural fuels: a review

Heat of combustion (HoC) is a key characteristic of fuels when analyzing and modeling wildfire scenarios. Despite significant differences in the structure of fuels from different environments, HoC is frequently considered a constant. This article briefly reviews methods used to describe natural fuels and the various different definitions of HoC. We also summarize measured values of HoC and elemental analyses of 238 plant genera reported in 28 papers since 1973. A statistical analysis of these data provided mean values and standard deviations of HoC for fuels according to six broad plant functional groups. Permutational Multivariate Analysis of Variance (PERMANOVA) demonstrated significant differences in the HoC with ground fuels and softwoods having particularly high values. Net heat of combustion was calculated for four fuel groups and the tabulated data may help to improve wildfire modeling and highlights fuels where further measurements of HoC are required

Patterns of technical change: a geometrical analysis using the wage–profit rate schedule

In this paper we examine some basic stylized facts of economic growth according to the modern restatement of the classical theory of income distribution. In particular, we make use of a wage–profit frontier in order to explore the patterns of technical change experienced by a set of 18 industrialized economies, during the last 40 years. Our main purpose is to document the evolution of technical change. Using empirical evidence from the Italian industry, we also make an attempt to provide an explanation to data from a classical perspective, alternative to the standard approach founded on the aggregate production function.fossil production function, Marx‐biased technical change, wage–profit rate schedule, E11, O40, O52,