A 2D model of Causal Set Quantum Gravity: The emergence of the continuum

Non-perturbative theories of quantum gravity inevitably include configurations that fail to resemble physically reasonable spacetimes at large scales. Often, these configurations are entropically dominant and pose an obstacle to obtaining the desired classical limit. We examine this "entropy problem" in a model of causal set quantum gravity corresponding to a discretisation of 2D spacetimes. Using results from the theory of partial orders we show that, in the large volume or continuum limit, its partition function is dominated by causal sets which approximate to a region of 2D Minkowski space. This model of causal set quantum gravity thus overcomes the entropy problem and predicts the emergence of a physically reasonable geometry.Comment: Corrections and clarifications. Conclusions unchange

Hypercube orientations with only two in-degrees

We consider the problem of orienting the edges of the $n$-dimensional hypercube so only two different in-degrees $a$ and $b$ occur. We show that this can be done, for two specified in-degrees, if and only if an obvious necessary condition holds. Namely, there exist non-negative integers $s$ and $t$ so that $s+t=2^n$ and $as+bt=n2^{n-1}$. This is connected to a question arising from constructing a strategy for a "hat puzzle."Comment: 9 pages, 4 figure

Recording the stream of consciousness: a practice-led study of serial drawing

How is a process of serial drawing understood to record the phenomenological stream of consciousness that underpins it? This research question emerges from a hypothesis driving the research: that when considered as a form of expression which speaks in a particular way (Tormey, 2007), drawing re-presents ( records ) the stream of consciousness underpinning it in a rather fundamental manner. The purpose of this first person, practice-led research is to question how this hypothesis is understood, treating it as an assumption to be tested via practice and theory combined. Within the research this hypothesis is linked to both the wider assumption that drawing records thought (Rosand, 2002) and to the contemporary idea that drawing is a form of perpetual becoming (Hoptman, 2002; de Zegher & Butler, 2010) given the temporality which underpins the act of drawing. To help facilitate investigation of the hypothesis, the assumption that drawing records thought is duly suspended (bracketed) for the duration of the research, allowing the structure and process of serially developed drawing (Chavez, 2004) in conjunction with first-person methods for approaching phenomenal consciousness (Varela & Shear, 1999; Depraz, 1999) to investigate it in practical terms. The significance of the research resides in a scrutiny of the drawing process, undertaken in close relation to Husserl s (1931/2012; 1950/1999) Phenomenology. As a result, the phenomenon of drawing is re-described as a self-temporalizing phenomenon, emphasising how the appearance of drawing (noun) not only re-presents the prior act of drawing (verb) which produced it, but also provides the practitioner with a look ahead, indicating the hope and expectation of drawings not yet made. This claim emerges via the specific manner in which my serially developed drawings demonstrate re-presenting the streaming of consciousness described (in Husserlian terms) as the self-temporalization of consciousness, experienced within the duration of now. This phenomenological description of how drawing operates builds upon Rawson s (1969/1987) statement regarding the special charm of drawing - the underlying quality of movement that drawings (noun) exhibit on the basis they were drawn. Husserl s protentional focus on hope and expectation (de Warren, 2009) allows the research to expand upon this idea, describing the underlying movement within drawing as a form of self-temporalization that also points ahead to what is not yet drawn. This forward looking, practitioner centred claim is intended to compliment the focus on trace and memory that a proportion of the current critical discourse on drawing remains engaged with (Newman M, 1996; Tormey, 2007; Newman & de Zegher, 2003; Derrida J, 1993)

ANCHOR

ANCHOR Fourteen artistic responses to the question: what is an outline? As a piece of practice-led artistic research formed across drawing, print, photography and text, ANCHOR questions the idea that the concept of outline can be defined in the traditional sense

CONTESTING THE BOUNDARIES OF RELIGION IN SOCIAL MOBILIZATION

This paper seeks to contribute to an understanding of the dynamics of religion in social mobilization. It argues that existing approaches to the study of the role of religion in social mobilization have been insufficiently nuanced and have failed to probe the multiple and often contradictory influences that religion can have on mobilization channels. On the basis of three qualitative case studies, from Malaysia, Bangladesh and the United Kingdom, we identify three key ingredients for religion to act as a catalyst for social mobilization: theological resources, sacred spaces, and their interaction with the wider context. This leads us to conclude that the boundaries of the ‘religious’ dimension of social mobilization are fluid, and that the religious element of social mobilization can never be disentangled from its social and political context

A Model-Based Design Tool for Systems-Level Spacecraft Design

It is standard practice to mathematically model and analyze the various subsystems that make up a spacecraft, to ensure that they will function correctly when built. However, the system-level behavior of the spacecraft is generally understood in much less rigorous terms. This leaves the spacecraft system far more vulnerable than the subsystems to unforeseen design errors which may not manifest themselves until the integration and test phase, when design changes are most expensive in terms of cost and schedule. In this paper, we present Spacecraft Design Workbench, an extensible graphical design tool built upon the Generic Modeling Environment (GME) tool infrastructure, and intended to allow spacecraft systems engineers to model and analyze proposed spacecraft system designs in a rigorous manner. The graphical models defined by our tool have an underlying formal behavior semantics rooted in the Communicating Sequential Processes process algebra, which permits these models to be analyzed using off-the-shelf tools. As a proof-of-concept, we provide a small example that illustrates the application of our tool to the specification of a simple scientific spacecraft

Computing optimal strategies for a cooperative hat game

We consider a `hat problem' in which each player has a randomly placed stack of black and white hats on their heads, visible to the other player, but not the wearer. Each player must guess a hat position on their head with the goal of both players guessing a white hat. We address the question of finding the optimal strategy, i.e., the one with the highest probability of winning, for this game. We provide an overview of prior work on this question, and describe several strategies that give the best known lower bound on the probability of winning. Upper bounds are also considered here