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Strong correlations at topological insulator surfaces and the breakdown of the bulk-boundary correspondence
The criteria for strong correlations on surfaces of three-dimensional
topological insulators are discussed. Usually, the Coulomb repulsion at such
surfaces is too weak for driving a phase transition to a strongly correlated
regime. I discuss a mechanism and possibilities of its experimental
implementation by which the strength of the Coulomb interaction can be tuned
over a wide range. In the strongly interacting regime, the surface states are
gapped, even though the topological classification of the bulk band structure
predicts gapless surface states
Media Philosophy— A Reasonable Programme?
It is beyond any doubt that media have an enormous impact on our media-culture societies. Media in?uence our perception and our knowledge, our memory as well as our emotions. They create public spheres and public opinions and give rise to media realities. Media shape our socialisation and our communality. They transform economy, politics, science, religion and law. “What we know about our society, even about our world we are living in, we know via the mass media.” (Luhmann 1996:9; my translation) Accordingly, “the media” have become a paramount subject of interdisciplinary discourses in the last decades all over the world. All these developments have become topics of scienti?c analyses as well as parts of media programmes. Since decades, various academic disciplines focused on an other-observation (“Fremdbeobachtung”) of the media from an external state, whereas the media increasingly tend to observe themselves as well as one another in order to transform this self-observation into parts of their respective programmes. The other-observation is carried out either by scholars of communication- and/or media theory or by philosophers; but whereas the former are organised in academic disciplines, no established discipline entitled “media philosophy” exists until today. Instead, the various approaches to philosophical analyses of media are heterogeneous and lack a solid theoretical basis as well as a disciplinary organisation. Some scholars even hold the view that media are not even within the province of philosophers. Some people deeply regret this deadlock regarding not only topics and discourses but also future jobs and positions for scholars of a discipline “media philosophy” to come. Others welcome this stalemate which gives room to creative solutions of thematic as well as of organisational matters. Let us have a short look at some of the foreseeable options. One of the actual media philosophical approaches concentrates its efforts on a reformulation of traditional philosophical topics in the framework of media ef?ciencies. The list of such topics is rather long and covers nearly all famous crucial subjects of philosophical discourses, reaching from reality, truth, culture, society, education or politics to time, space, emotion, subject or entertainment. This kind of rethinking or reformulating philosophical topics concentrates upon the question how—in the co-evolution of media systems and society—our daily experiences as well as our theoretical modellings of these topics have changed on the historical way from writing to the Internet
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