scholarly journals Quantum Spacetime, Noncommutative Geometry and Observers

Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 24
Author(s):  
Fedele Lizzi
Keyword(s):  
Noncommutative Geometry ◽  
Noncommutative Spaces ◽  
Quantum Spacetime

I discuss some issues related to the noncommutative spaces κ and its angular variant ρ-Minkowski with particular emphasis on the role of observers.

scholarly journals COMPLEX GRAVITY AND NONCOMMUTATIVE GEOMETRY

2001 ◽  
Vol 16 (05) ◽  
pp. 759-766 ◽  
Author(s):  
ALI H. CHAMSEDDINE
Keyword(s):  
Noncommutative Geometry ◽  
Space Time ◽  
Specific Form ◽  
Antisymmetric Tensor ◽  
Gauge Invariant ◽  
Diffeomorphism Invariance ◽  
Open Strings ◽  
Noncommutative Spaces

The presence of a constant background antisymmetric tensor for open strings or D-branes forces the space-time coordinates to be noncommutative. An immediate consequence of this is that all fields get complexified. By applying this idea to gravity one discovers that the metric becomes complex. Complex gravity is constructed by gauging the symmetry U(1, D-1). The resulting action gives one specific form of nonsymmetric gravity. In contrast to other theories of nonsymmetric gravity the action is both unique and gauge invariant. It is argued that for this theory to be consistent one must prove the existence of generalized diffeomorphism invariance. The results are easily generalized to noncommutative spaces.

INTRODUCTION TO BRAIDED QUANTUM FIELD THEORY

2000 ◽  
Vol 14 (22n23) ◽  
pp. 2461-2466 ◽  
Author(s):  
ROBERT OECKL
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Group ◽  
Noncommutative Geometry ◽  
Quantum Groups ◽  
Symmetry Groups ◽  
Quantum Field ◽  
Noncommutative Spaces ◽  
Small Scales ◽  
Group Symmetries

Indications from various areas of physics point to the possibility that space-time at small scales might not have the structure of a manifold. Noncommutative geometry provides an attractive framework for a perhaps more accurate description of nature. It encompasses the generalisation of spaces to noncommutative spaces and of symmetry groups to quantum groups. This motivates efforts to extend quantum field theory to noncommutative spaces and quantum group symmetries. One also expects that divergences of conventional theories might be regularised in this way.

scholarly journals THE ADHM CONSTRUCTION OF INSTANTONS ON NONCOMMUTATIVE SPACES

2011 ◽  
Vol 23 (03) ◽  
pp. 261-307 ◽  
Author(s):  
SIMON BRAIN ◽  
WALTER D. VAN SUIJLEKOM
Keyword(s):  
Euclidean Space ◽  
Noncommutative Geometry ◽  
Space Time ◽  
Point Of View ◽  
Noncommutative Space ◽  
Special Cases ◽  
Noncommutative Spaces ◽  
Coordinate Algebra ◽  
Classical Construction

We present an account of the ADHM construction of instantons on Euclidean space-time ℝ4 from the point of view of noncommutative geometry. We recall the main ingredients of the classical construction in a coordinate algebra format, which we then deform using a cocycle twisting procedure to obtain a method for constructing families of instantons on noncommutative space-time, parametrized by solutions to an appropriate set of ADHM equations. We illustrate the noncommutative construction in two special cases: the Moyal–Groenewold plane [Formula: see text] and the Connes–Landi plane [Formula: see text].

scholarly journals MINIMAL LENGTH IN QUANTUM SPACE AND INTEGRATIONS OF THE LINE ELEMENT IN NONCOMMUTATIVE GEOMETRY

2012 ◽  
Vol 24 (05) ◽  
pp. 1250010 ◽  
Author(s):  
PIERRE MARTINETTI ◽  
FLAVIO MERCATI ◽  
LUCA TOMASSINI
Keyword(s):  
Noncommutative Geometry ◽  
Line Element ◽  
Geodesic Distance ◽  
High Energy ◽  
Minimal Length ◽  
Quantum Space ◽  
Spectral Distance ◽  
Moyal Plane ◽  
The One ◽  
Quantum Spacetime

We question the emergence of a minimal length in quantum spacetime, comparing two notions that appeared at various points in the literature: on the one side, the quantum length as the spectrum of an operator L in the Doplicher Fredenhagen Roberts (DFR) quantum spacetime, as well as in the canonical noncommutative spacetime (θ-Minkowski); on the other side, Connes' spectral distance in noncommutative geometry. Although in the Euclidean space the two notions merge into the one of geodesic distance, they yield distinct results in the noncommutative framework. In particular, in the Moyal plane, the quantum length is bounded above from zero while the spectral distance can take any real positive value, including infinity. We show how to solve this discrepancy by doubling the spectral triple. This leads us to introduce a modified quantum length d′L, which coincides exactly with the spectral distance dD on the set of states of optimal localization. On the set of eigenstates of the quantum harmonic oscillator — together with their translations — d′L and dD coincide asymptotically, both in the high energy and large translation limits. At small energy, we interpret the discrepancy between d′L and dD as two distinct ways of integrating the line element on a quantum space. This leads us to propose an equation for a geodesic on the Moyal plane.

scholarly journals Non-linear σ-models in noncommutative geometry: fields with values in finite spaces

2003 ◽  
Vol 18 (33n35) ◽  
pp. 2371-2379 ◽  
Author(s):  
Ludwik Dabrowski ◽  
Thomas Krajewski ◽  
Giovanni Landi
Keyword(s):  
Projective Space ◽  
Noncommutative Geometry ◽  
Moduli Space ◽  
Topological Charge ◽  
Complex Structure ◽  
Noncommutative Tori ◽  
Noncommutative Spaces ◽  
Non Linear ◽  
Finite Spaces

We study σ-models on noncommutative spaces, notably on noncommutative tori. We construct instanton solutions carrying a nontrivial topological charge q and satisfying a Belavin-Polyakov bound. The moduli space of these instantons is conjectured to consists of an ordinary torus endowed with a complex structure times a projective space [Formula: see text].

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

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