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Hartmann Römer

Publications and source records attributed to Hartmann Römer.

9 recordsLinked to original sources
arXiv2018

Symmetry and Contextuality

The general concept of symmetry is realized in manifold ways in different realms of reality, such as plants, animals, minerals, mathematical objects or human artefacts in literature, fine arts and society. In order to arrive at a common ground for this variedness a very general conceptualization of symmetry is proposed: Existence of substitutions, which, in the given context, do not lead to an essential change. This simple definition has multiple consequences: -The context dependence of the notion of symmetry is evident in the humanities but by no means irrelevant yet often neglected in science. The subtle problematic of concept formation and the ontological status of similarities opens up. -In general, the substitutions underlying the concept of symmetry are not really performed but remain in a state of virtuality. Counterfactuality, freedom and creativity come into focus. The detection of previously hidden symmetries may provide deep and surprising insights. -Related to this, due attention is devoted to the aesthetic dimension of symmetry and the breaking of it. -Finally, we point out to what extent life is based on the interplay between order and freedom, between full and broken symmetry.

physics.hist-ph↗
arXiv2016

Generalized Quantum Theory, Contextual Emergence and Non-Hierarchic Alternatives

The concept of emergence is critically analyzed in particular with respect to the assumed emergence of mental properties from a neuronal basis. We argue that so-called contextual emergence is needed to avoid an eliminatory reductionism. Quantum-like features of the emergent qualities are to be expected. As a consequence, non-causal relations like entanglement correlations have to be considered as full fledged elements of reality. "Observable extension" is proposed as a contextual alternative to emergence avoiding the asymmetry between purportedly basic and emergent properties.

physics.hist-ph↗
arXiv2013

Now, Factuality and Conditio Humana

The relationship between inner and outer time is discussed. Inner time is intrinsically future directed and possesses the quality of a distinguished "now". Both of these qualities get lost in the operationalized external physical time, which, advancing towards more fundamental physics, tends to become more similar to space and even fade away as a fundamental notion. However, inner time as a constitutive feature of human existence holds its place in the heart of quantum theory and thermodynamics.

physics.hist-ph↗
arXiv2012

Why Do We See a Classical World?

From a general abstract system theoretical perspective, a quantum-like system description in the spirit of a generalized Quantum Theory may appear to be simpler and more natural than a classically inspired description. We investigate the reasons why we nevertheless conceive ourselves embedded into a classically structured world. Categorial, physical and pragmatic reasons are proposed as explanations.

quant-ph↗
arXiv2012

Generalized Quantum Theory: Overview and Latest Developments

The main formal structures of Generalized Quantum Theory are summarized. Recent progress has sharpened some of the concepts, in particular the notion of an observable, the action of an observable on states (putting more emphasis on the role of proposition observables), and the concept of generalized entanglement. Furthermore, the active role of the observer in the structure of observables and the partitioning of systems is emphasized.

quant-ph↗
arXiv2003

Currents and the Energy-Momentum Tensor in Classical Field Theory: A fresh look at an Old Problem

We give a comprehensive review of various methods to define currents and the energy-momentum tensor in classical field theory, with emphasis on a geometric point of view. The necessity of ``improving'' the expressions provided by the canonical Noether procedure is addressed and given an adequate geometric framework. The main new ingredient is the explicit formulation of a principle of ``ultralocality'' with respect to the symmetry generators, which is shown to fix the ambiguity inherent in the procedure of improvement and guide it towards a unique answer: when combined with the appropriate splitting of the fields into sectors, it leads to the well-known expressions for the current as the variational derivative of the matter field Lagrangian with respect to the gauge field and for the energy-momentum tensor as the variational derivative of the matter field Lagrangian with respect to the metric tensor. In the second case, the procedure is shown to work even when the matter field Lagrangian depends explicitly on the curvature, thus establishing the correct relation between scale invariance, in the form of local Weyl invariance ``on shell'', and tracelessness of the energy-momentum tensor, required for a consistent definition of the concept of a conformal field theory.

hep-th↗
arXiv2002

A general construction of Poisson brackets on exact multisymplectic manifolds

In this note the long standing problem of the definition of a Poisson bracket in the framework of a multisymplectic formulation of classical field theory is solved. The new bracket operation can be applied to forms of arbitary degree. Relevant examples are discussed and important properties are stated with proofs sketched.

math-ph↗
arXiv2001

A Poisson Bracket on Multisymplectic Phase Space

A new Poisson bracket for Hamiltonian forms on the full multisymplectic phase space is defined. At least for forms of degree n-1, where n is the dimension of space-time, Jacobi's identity is fulfilled.

math-ph↗