String Theory - From Physics to Metaphysics

Currently, string theory represents the only advanced approach to a unification of all interactions, including gravity. In spite of the more than thirty years of its existence it did not make any empirically testable predictions. And it is completely unknown which physically interpretable principles could form the basis of string theory. At the moment, "string theory" is no theory at all, but rather a labyrinthic structure of mathematical procedures and intuitions which get their justification from the fact that they, at least formally, reproduce general relativity and the standard model of elementary particle physics as low energy approximations. However, there are now strong indications that string theory does not only reproduce the dynamics and symmetries of our standard model, but a plethora of different scenarios with different low energy nomologies and symmetries. String theory seems to describe not only our world, but an immense landscape of possible worlds. So far, all attempts to find a selection principle which could be motivated intratheoretically remained without success. So, recently the idea that the low energy nomology of our world, and therefore also the observable phenomenology, could be the result of an anthropic selection from a vast arena of nomologically different scenarios entered string theory. Although multiverse scenarios and anthropic selection are not only motivated by string theory, but lead also to a possible explanation for the fine tuning of the universe, they are concepts which transcend the framework defined by the epistemological and methodological rules which conventionally form the basis of physics as an empirical science.Comment: 30 pages, submitted to "Physics and Philosophy" (Online-Journal

A short note on the problematic concept of excess demand in asset pricing models with mean-variance optimization

Referring to asset pricing models where demand is proportional to excess returns and said to be derived from a mean-variance optimization problem, the note formulates what probably is common knowledge but hardly ever made an explicit subject of discussion. This is an insufficient distinction between the desired holding of the risky asset on the part of the speculative agents, which is the solution to the optimization problem and usually directly presented as excess demand, and the desired change in this holding, which is what should reasonably constitute the excess demand on the market. The note arrives at the conclusion that in models with a market maker the story of the maximization of expected wealth should be dropped

Quantum Gravity: Has Spacetime Quantum Properties?

The incompatibility between GR and QM is generally seen as a sufficient motivation for the development of a theory of Quantum Gravity. If - so a typical argumentation - QM gives a universally valid basis for the description of all natural systems, then the gravitational field should have quantum properties. Together with the arguments against semi-classical theories of gravity, this leads to a strategy which takes a quantization of GR as the natural avenue to Quantum Gravity. And a quantization of the gravitational field would in some sense correspond to a quantization of geometry. Spacetime would have quantum properties. But, this strategy will only be successful, if gravity is a fundamental interaction. - What, if gravity is instead an intrinsically classical phenomenon? Then, if QM is nevertheless fundamentally valid, gravity can not be a fundamental interaction. An intrinsically classical gravity in a quantum world would have to be an emergent, induced or residual, macroscopic effect, caused by other interactions. The gravitational field (as well as spacetime) would not have any quantum properties. A quantization of GR would lead to artifacts without any relation to nature. The serious problems of all approaches to Quantum Gravity that start from a direct quantization of GR or try to capture the quantum properties of gravity in form of a 'graviton' dynamics - together with the, meanwhile, rich spectrum of approaches to an emergent gravity and/or spacetime - make this latter option more and more interesting for the development of a theory of Quantum Gravity. The most advanced emergent gravity (and spacetime) scenarios are of an information-theoretical, quantum-computational type.Comment: 31 page

String Theory - Nomological Unification and the Epicycles of the Quantum Field Theory Paradigm

String Theory is the result of the conjunction of three conceptually independent elements: (i) the metaphysical idea of a nomological unity of the forces, (ii) the model-theoretical paradigm of Quantum Field Theory, and (iii) the conflict resulting from classical gravity in a quantum world. String Theory is sometimes assumed to solve this conflict: by means of an application of the model-theoretical apparatus of (perturbative) Quantum Field Theory. But, String Theory does not really solve the conflict. Rather it exemplifies the inadequacy of this model-theoretical apparatus in the context of Quantum Gravity: After several decades of development it still exists only in an essentially perturbative formulation (with minor non-perturbative extensions and vague ideas with regard to a possible non-perturbative formulation). And, due to its quantum field theoretical heritage, it is conceptually incompatible with central implications of General Relativity, especially those resulting from the general relativistic relation between gravity and spacetime. All known formulations of String Theory are background-dependent. On the other hand, it was not even possible to reproduce the Standard Model. Instead, String Theory led to a multitude of internal problems - and to the plethora of low-energy scenarios with different nomologies and symmetries, known as the String Landscape. All attempts to find a dynamically motivated selection principle remained without success, leaving String Theory without any predictive power. The nomological unification of the fundamental forces is only achieved in a purely formal way within the model-theoretical paradigm of Quantum Field Theory - by means of physically unmotivated epicycles like higher dimensionality, Calabi-Yau spaces, branes, etc.Comment: 23 page

Workers\u27 Resistance Against Nazi Germany at the International Labour Conference 1933

Eighty years ago, the delegation of national socialist Germany made an early exit from the International Labour Conference. An attempt to install the German Labour Front as legitimate worker representatives, instead of the free trade unions, had failed due to resistance from the Workers’ Group and, not least, the persistent silence maintained by Wilhelm Leuschner, the German unions’ representative on the ILO Governing Body. Wilhelm Leuschner was a courageous man whose actions were carefully thought through, and right from the start he was an opponent of the Nazi regime. As a resistance fighter for Germany and against Hitler, he was murdered by the Nazis in 1944. In June 1933, his participation in the International Labour Conference opened up the possibility of going into exile, but he opted instead to resist from inside Germany. That decision no doubt explains why he chose to pillory the regime by keeping silent at the International Labour Conference, rather than voicing public protests. Like so many other people in 1933, Leuschner had no idea of just how far the national socialists would later take their lust for annihilation and terror. But what was quite clear by 2 May 1933 at the latest, when the Nazis banned the free German trade unions, occupied their premises and packed countless trade unionists off to the concentration camps, was that even gestures of submission and far-reaching concessions to the Nazis would do nothing to ensure the organizational survival of trade unions that three generations of German workers had built up into one of Europe’s most powerful trade union organizations. At the same time, open political resistance in June 1933 would almost certainly have meant ill-treatment, torture and imprisonment, without in any way improving the chances of success. In this situation, Wilhelm Leuschner needed to adopt the right tactics for his appearance at the International Labour Conference, and the Workers’ Group had to ponder how it could effectively show solidarity with the German unions without exposing German trade unionists, and Wilhelm Leuschner in particular, to even greater danger. Reiner Tosstorff’s study sets out to describe and understand this complex set of circumstances. And looking beyond this concrete individual case, it still raises issues that are still relevant today