Quantum Geometry and its Implications for Black Holes

General relativity successfully describes space-times at scales that we can observe and probe today, but it cannot be complete as a consequence of singularity theorems. For a long time there have been indications that quantum gravity will provide a more complete, non-singular extension which, however, was difficult to verify in the absence of a quantum theory of gravity. By now there are several candidates which show essential hints as to what a quantum theory of gravity may look like. In particular, loop quantum gravity is a non-perturbative formulation which is background independent, two properties which are essential close to a classical singularity with strong fields and a degenerate metric. In cosmological and black hole settings one can indeed see explicitly how classical singularities are removed by quantum geometry: there is a well-defined evolution all the way down to, and across, the smallest scales. As for black holes, their horizon dynamics can be studied showing characteristic modifications to the classical behavior. Conceptual and physical issues can also be addressed in this context, providing lessons for quantum gravity in general. Here, we conclude with some comments on the uniqueness issue often linked to quantum gravity in some form or another.Comment: 16 pages, Plenary talk at ``Einstein's Legacy in the New Millenium,'' Puri, India, December 200

Ernst Jünger and the problem of Nihilism in the age of total war

As a singular witness and actor of the tumultuous twentieth century, Ernst Jünger remains a controversial and enigmatic figure known above all for his vivid autobiographical accounts of experience in the trenches of the First World War. This article will argue that throughout his entire oeuvre, from personal diaries to novels and essays, he never ceased to grapple with what he viewed as the central question of the age, namely that of the problem of nihilism and the means to overcome it. Inherited from Nietzsche’s diagnosis of Western civilization in the late nineteenth century to which he added an acute observation of the particular role of technology within it, Jünger would employ this lens to make sense of the seemingly absurd industrial slaughter of modern war and herald the advent of a new voluntarist and bellicist order that was to imminently sweep away timorous and decadent bourgeois societies obsessed with security and self-preservation. Jünger would ultimately see his expectations dashed, including by the forms of rule that National Socialism would take, and eventually retreated into a reclusive quietism. Yet he never abandoned his central problematique of nihilism, developing it further in exchanges with Martin Heidegger after the Second World War. And for all the ways in which he may have erred, his life-long struggle with meaning in the age of technique and its implications for war and security continue to make Jünger a valuable interlocutor of the present

Afterword : Beyond the naïve mantra of criticality in education (research)?

In this chapter Chen and Dervin suggest moving beyond a simplistic mantra of criticality, explaining that claiming and performing criticality does not mean one is really critical in (education) research. The authors start by referring to a group of Finnish students’ reflections about interculturality, for whom criticality meant: asking questions, questioning, reconsidering one’s assumptions, and unthinking. Chen and Dervin claim that, for other students, anywhere else in the world or from a different major at the same university, criticality might mean the same or something different. They thus advocate turning one’s attention to the question whose criticality can assess criticality? They also suggest an open-ended perspective whereby educators and researchers must accept contradictions, debates, and the symbolic violence of being questioned, of having their criticality critiqued. For the authors, this also means thinking for oneself to avoid being enslaved by pet theories, gurus and analytical stereotypes (amongst others) and to stop thinking that ‘one’s’ criticality is better than others’.Peer reviewe

Rapid and selective absorption of plant defense compounds from the gut of a sequestering insect

Many herbivorous insects exploit defense compounds produced by their host plants for protection against predators. Ingested plant defense compounds are absorbed via the gut epithelium and stored in the body, a physiological process that is currently not well understood. Here, we investigated the absorption of plant defense compounds from the gut in the horseradish flea beetle, Phyllotreta armoraciae, a specialist herbivore known to selectively sequester glucosinolates from its brassicaceous host plants. Feeding experiments using a mixture of glucosinolates and other glucosides not found in the host plants showed a rapid and selective uptake of glucosinolates in adult beetles. In addition, we provide evidence that this uptake mainly takes place in the foregut, whereas the endodermal midgut is the normal region of absorption. Absorption via the foregut epithelium is surprising as the apical membrane is covered by a chitinous intima. However, we could show that this cuticular layer differs in its structure and overall thickness between P. armoraciae and a non-sequestering leaf beetle. In P. armoraciae, we observed a thinner cuticle with a less dense chitinous matrix, which might facilitate glucosinolate absorption. Our results show that a selective and rapid uptake of glucosinolates from the anterior region of the gut contributes to the selective sequestration of glucosinolates in P. armoraciae

Suppressing Unwanted Memories Reduces Their Unintended Influences

The ability to control unwanted memories is critical for maintaining cognitive function and mental health. Prior research has shown that suppressing the retrieval of unwanted memories impairs their retention, as measured on intentional (direct) memory tests. Here we review emerging evidence revealing that retrieval suppression can also reduce the unintended influence of suppressed traces. In particular, retrieval suppression (1) gradually diminishes the tendency for memories to intrude into awareness, and (2) reduces memories’ unintended expressions on indirect memory tests. We present a neural account in which, during suppression, retrieval cues elicit hippocampally-triggered neocortical activity that briefly reinstates features of the original event, which, in turn, are suppressed by targeted neocortical and hippocampal inhibition. This reactivation-dependent reinstatement principle could provide a broad mechanism by which suppressing retrieval of intrusive memories limits their indirect influences

Nietzschean modes of gender construction in a post-feminist age

An arrogance of certainty besets discourses of gender in today’s culture, and denigrating as well as overly affirming accounts of masculinity leave theindividual man at risk of either self-loathing or self-aggrandizing. This article will look at various lay accounts of masculinity and the dynamics of itsconstruction in opposition to culturally dominant moral codes, and will interrogate the underlying philosophical positions at work through Nietzsche’s Genealogy of Morality. In doing so, we propose that it is helpful to see Nietzsche as an early philosopher of difference, and embrace a less fixed approach to ontologies of gender accordingly