Algebraically special coplanar shear-free perfect fluids in general relativity

We investigate all algebraically special, not conformally flat, shear-free, isentropic (p(w), w + p ≠ 0), perfect fluid solutions of Einstein's field equations. We show, using the GHP formalism, that if the repeated principle null direction of the Weyl tensor is coplanar with the fluid's 4-velocity and vorticity vector (assumed nonzero), then the fluid's expansion must vanish.

Symbolic computation and perfect fluids in general relativity

Focuses on two areas within the field of general relativity. Firstly, the history and implications of the long-standing conjecture that general relativistic, shear-free perfect fluids which obey a barotropic equation of state p = p(w) such that w + p = 0, are either non-expanding or non-rotating. Secondly the application of the computer algebra system Maple to the area of tetrad formalisms in general relativity.

Purely magnetic spacetimes in general relativity

Given the deep links between Maxwell's equations and General Relativity, it is natural to ask whether there exist solutions of the field equations which are purely magnetic, like Dirac's magnetic monopole. The thesis succeeds in producing two entirely new families of purely magnetic solutions.

Hybrid perspectives : defining the relativity of culture and identity through migration experiences

This paper examines how culture and identity can be relatively defined through hybrid perspectives in relation to migration experiences. Addressing and portraying definitions of culture and identity is crucial in understanding how notions of such issues connect and initiate the migrant subject through new experiences, perspectives and ways of being. In enunciating the transitions from home to a new place, and elaborating on the rupture of an inherited culture and grounded identity, I refer to them through self-reflexive perspectives. The search for meaning through appraisals of cultural lineage and linguistic capital through a Diaspora, a post colonial history and lived life experiences from my home country, pre-empts the ambivalent and hybrid status in defining culture(s) and identit(ies). It is crucial to recognise how challenges for adaptation to new culture, language, societal norms, and differences in class, nationality, race and gender play specific roles in the migrant experience. My current experiences of migration to Australia are narrations of encountered difficulties, fears, inhibitions, new aspirations, perceptions and perspectives, which map an ‘identity crisis.’ From this narrative structure, I investigate through my ongoing PhD study, how my artistic expression and representations progress towards experiences, and themes that metaphorically reflect, inspire and enact the hybrid structures of culture(s) and identit(ies). Explored reflexively my representations suggest how the ‘liminal space’ or the ‘third space,’ (Bhabha, 1990) express transitions about the ‘self’ and my artistic expression, which enable further reflection and positions to emerge and extend to metaphorical expressions.

TensorPack : a Maple-based software package for the manipulation of algebraic expressions of tensors in general relativity

In this paper we: (1) introduce TensorPack, a software package for the algebraic manipulation of tensors in covariant index format in Maple; (2) briefly demonstrate the use of the package with an orthonormal tensor proof of the shearfree conjecture for dust. TensorPack is based on the Riemann and Canon tensor software packages and uses their functions to express tensors in an indexed covariant format. TensorPack uses a string representation as input and provides functions for output in index form. It extends the functionality to basic algebra of tensors, substitution, covariant differentiation, contraction, raising/lowering indices, symmetry functions and other accessory functions. The output can be merged with text in the Maple environment to create a full working document with embedded dynamic functionality. The package offers potential for manipulation of indexed algebraic tensor expressions in a flexible software environment.

Speculative fictions for understanding global change environments: two thought experiments

The purpose of a thought experiment, as the term was used by quantum and relativity physicists in the early part of the twentieth century, was not prediction (as is the goal of classical experimental science), but more defensible representations of present ‘realities’. Speculative fictions, from Mary Shelley's Frankenstein to the Star Wars cinema saga, can be read as sociotechnical thought experiments that produce alternative representations of present circumstances and uncertainties, and anticipate and critique possible futures. In this essay I demonstrate how two examples of popular speculative fictions, Frank Herbert's Dune (1965) and Ursula Le Guin's The Telling (2000), function as thought experiments that problematise global transitions in their respective eras. I argue that critical readings of such stories can help us to anticipate, critique, and respond constructively to social and cultural changes and change environments within nation-states that constitute, and are constituted by, global change processes and their effects.

Democracy, global transitions, and education : using speculative fictions as thought experiments in anticipatory critical inquiry

The purpose of a thought experiment, as the term was used by quantum and relativity physicists in the early part of the twentieth century, was not prediction (as is the goal of classical experimental science), but more defensible representations of present 'realities'. Indeed, one of the best-known examples of a thought experiment ('Schrodinger's cat') demonstrates the impossibility of prediction at the quantum level. Speculative fictions, from Mary Shelley's Frankenstein to the Star Wars saga, can be read as socio-technical thought experiments that can help us to apprehend and comprehend present 'realities' and uncertainties, and to anticipate and critique possible futures. In this paper I will demonstrate how two examples of popular speculative fictions, Frank Herbert's Dune (1965) and Ursula Le Guin's The Telling (2000), can be read as thought experiments that describe problematic aspects of contemporary social and cultural transformations. I will argue that critical and deconstructive readings of these novels can help us to produce anticipatory critiques of possible ways in which democratic institutions are being transformed by globalisation. I will conclude by considering the implications of such anticipatory critiques for generating questions, problems and issues in educational inquiry and for choosing appropriate methodologies for investigating them.

Interaction perspectives of individuals and destination marketing organizations in the tourism network of Australia

This paper seeks to assess the nature, perspectives and characteristics of interactions in the tourism network in Australia. The pattern of interactions between network participants is crucial in defining the network and its boundaries. Ford and Hakansson (2007) develop a structure of interactions between participants in a network. Time dimensions of the interactions are sequence, ordering and trajectory. Relativity dimensions are jointness, interdependence and heterogeneity. Interaction can be problem solving both incurring costs and producing benefits.
There are two stages of this research. The first stage obtained the perspectives from 35 organizations regarding the challenges facing tourism, key growth segments, brand and promotional strategies and customer insights and satisfaction levels. The second stage of this research uses follow up personal interviews and assesses the interaction patterns among network participants. The sequence, ordering and trajectory of the interactions are examined as are the jointness, interdependence and heterogeneity of the interactions. A network map is produced based on the frequency and importance of the communications and interactions. The research will also address key questions identified by Johnston, Peters and Gassenheimer (2006). Is the network characterized by tighter or looser coupling? How important is collaboration to the survival (or success) of each participant?

New way of seeing things : Ernst Troeltsch and the theological agenda

The aim of this thesis, as set out in the Introduction, is to assess the (seminal) significance of Troeltsch as one who set the agenda for twentieth century theology, particularly modern sociopolitical theology, and whose thought still has a special relevance. The first main chapter deals with the implications of the philosophy of history for theology. The Protestant theological orthodoxy of Troeltsch's time was essential ahistorical: he thought this to be untenable. Theology had to come to terms with the historical method, which was ‘a leaven which transforms everything, and finally bursts all previous forms of theological method.’ This chapter discusses Troeltsch's work concerning the principles, the cultural matrix, and the philosophy of history. The second main chapter examines another main concern of Troeltsch, namely, the status of Christianity vis-a-vis other religions. The background to this was the increasing awareness of the existence of other religions and the question of relativity and universality which this posed. Troeltschfs major response was Die Absolutheit des Christentums in which the ideas of essence, Europeanism, and absolutism were discussed, The third, and longest, chapter looks at the impact of social theory on theology. Sociology gave Troeltsch ‘a new way of seeing things’, and this new perspective is to be seen pre-eminently in The Social Teaching of the Christian Churches. Discussion of this centres on the three main concepts that Troeltsch delineated, compromise, natural law, and church/sect typology.

Ethical relativism vs absolutism : research implications

Purpose – The constructs of relativism and absolutism have a significant role to play in the development of ethical theory; however, they are commonly simplified in their depictions and are philosophically more complex than we give them credit for. The purpose of this paper is to undertake an in-depth examination of ethical relativity and ethical absolutism before concluding with a discussion of which research implications warrant further investigation.
Design/methodology/approach – A descriptive, historical, anthological approach has been taken.
Findings – Ethical relativism is regrettably subject to a proliferation of related terminology and, in many instances with different meanings ascribed to similar terms. In addition, ethical relativity appears to attract different research perspectives that are heavily dependent on their academic origins. A clear distinction needs to be made between ethical and situational relativity. It is suggested that relativism is present in the process of moral justification and that ethical relativism should be analyzed from three levels: the individual level, the role and group level, and the cultural levels. The over-riding objection to ethical relativism rests on the consequences of accepting relativism, which undermines the existence and strength of global moral standards and the inherent positioning of ethical absolutism. Absolutism does not deny the existence of multiple moral practices evident around the world, but proposes that variations in ethical actions could still be rooted in common universal moral standards based on our requirements as human beings and the necessities of long-term survival.
Research limitations/implications – The ensuing discussions of relativism and absolutism open up a rich vein of research opportunities and suggest caution is required in regard to research methodologies. From a methodological perspective, care needs to be taken. For example, using hypothetical ethical dilemmas that are often unrelated to a specific industry or cultural setting has resulted in many researchers observing situational relativity rather than true ethical relativity.
Originality/value – This paper specifically examines whether there are differences in underlying and basic moral standards even though similarities in ethical behaviour have been determined, or whether differing ethical actions could, as the absolutists believe, originate from common universal standards despite apparent differences in perceptions and actions across cultures.

Plane wave scattering by a spherical di-electric particle in motion : a relativistic extension of the Mie theory

Light scattering from small spherical particles has applications in a vast number of disciplines including astrophysics, meteorology optics and particle sizing. Mie theory provides an exact analytical characterization of plane wave scattering from spherical dielectric objects. There exist many variants of the Mie theory where fundamental assumptions of the theory has been relaxed to make generalizations. Notable such extensions are generalized Mie theory where plane waves are replaced by optical beams, scattering from lossy particles, scattering from layered particles or shells and scattering of partially coherent (non-classical) light. However, no work has yet been reported in the literature on modifications required to account for scattering when the particle or the source is in motion relative to each other. This is an important problem where many applications can be found in disciplines involving moving particle size characterization. In this paper we propose a novel approach, using special relativity, to address this problem by extending the standard Mie theory for scattering by a particle in motion with a constant speed, which may be very low, moderate or comparable to the speed of light. The proposed technique involves transforming the scattering problem to a reference frame co-moving with the particle, then applying the Mie theory in that frame and transforming the scattered field back to the reference frame of the observer.

Placing space/time through photography’s old and new technologies

The discovery that an impressively strong 3-dimensional effect in a 2-dimensional photographic representation of natural outdoor scenes occurs when a single camera is directed around one point in the scene, thus drawing into relief the subject of attention and blurring the surrounding space, has important implications for understanding basic processes in 3-dimensional vision. For the development of new ways for generating 3D effects in motion and static representations of scenes we might well learn from photography’s old technologies, as well as digital technologies of the static print, which have yet to release the full impact of their potential in the representation of motion and space.

Shear-free perfect fluids with a solenoidal electric curvature

We prove that the vorticity or the expansion vanishes for any shear-free perfect fluid solution of the Einstein field equations where the pressure satisfies a barotropic equation of state and the spatial divergence of the electric part of the Weyl tensor is zero.

Shear-free perfect fluids with a γ-law equation of state

 We investigate all shear-free perfect fluid solutions of the Einstein field equations where the pressure and energy density satisfy a (Formula presented.)-law equation of state with (Formula presented.). We prove that such a fluid is either non rotating or non expanding. As a consequence, it follows by combining our result with those of Collins and Wainwright that any such shear-free perfect fluid which models either an expand universe or a collapsing star must in fact be a Friedmann–Robertson–Walker spacetime.