The brane world description of our universe entails a large extra dimension and fundamental scale gravity that may be lower than the Planck by several orders magnitude. An interesting consequence this scenario occurs in nature spherically-symmetric vacuum solutions to gravitational field equations, which often have properties quite distinct from standard black hole general relativity. In paper, collapse on four types null fluid, governed barotropic, polytropic, strange quark "bag" model...

We derive generalised uncertainty relations (GURs) for orbital angular momentum and spin in the recently proposed smeared-space model of quantum geometry. The implements a minimum length linear recovers both principle (GUP) extended (EUP), previously gravity literature, within single formalism. In this paper, we investigate consequences these results particles with extrinsic intrinsic obtain generalisations canonical so ( 3 ) su 2 algebras. find that, although SO symmetry is preserved on...

Abstract We show that the $$(1+3)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> -dimensional ‘superboost’ operators, proposed in Dragan and Ekert’s most recent work on superluminal reference frames (Dragan et al. Class Quantum Gravity 40(2): 025013, 2023), are simply canonical Lorentz boosts, expressed nonstandard notation. Their ‘superflip’, which...

We derive upper and lower bounds on the mass-radius ratio of stable compact objects in extended gravity theories, which modifications gravitational dynamics via-\'a-vis standard general relativity are described by an effective contribution to matter energy-momentum tensor. Our results include possibility a variable coupling between sector field valid for large class generalized models. The continuity Tolman-Oppenheimer-Volkoff equations expressed terms mass, density, pressure, given bare...

Major issues that limit the applicability of point-contact Andreev reflection (PCAR) spectroscopy for measurements transport spin polarization $(P)$ are investigated. We show analysis PCAR spectra on basis generalized Blonder-Tinkham-Klapwijk model may lead to degenerate solutions; i.e., straightforward determination $P$ from multiparameter fitting is ambiguous. have developed a refined method reduces ambiguity. This applied several test cases (copper, NiMnSb,...

The Compton wavelength gives the minimum radius within which mass of a particle may be localized due to quantum effects, while Schwarzschild maximum black hole classial gravity. In mass-radius diagram, two lines intersect near Planck point (l P , m ), where gravity effects become significant. Since canonical (non-gravitational) mechanics is based on concept wave-particle duality, encapsulated in de Broglie relations, these relations should break down ). It unclear what physical...

Noncommutativity in physics has a long history, tracing back to classical mechanics. In recent years, many new developments theoretical physics, and practical applications rely on different techniques of noncommutative algebras. this review, we introduce the basic concepts range areas, including condensed matter systems, statistical mechanics, quantum present some important examples algebras, Poisson brackets, Heisenberg algebra, Lie Clifford Dirac Snyder Nambu Potential structures...

We consider the possible existence of gravitationally bound general relativistic strings consisting Bose-Einstein condensate (BEC) matter which is described, in Newtonian limit, by zero temperature time-dependent nonlinear Schr\"odinger equation (the Gross-Pitaevskii equation), with repulsive interparticle interactions. In Madelung representation wave function, quantum dynamics can be formulated terms classical continuity and hydrodynamic Euler equations. case a quartic nonlinearity,...

Phenomenological approaches to quantum gravity implement a minimum resolvable length-scale but do not link it an underlying formalism describing geometric superpositions. Here, we introduce intuitive approach in which points the classical spatial background are delocalised, or 'smeared', giving rise entangled superposition of geometries. The model uses additional degrees freedom parameterise superposed backgrounds. Our contains both length and momentum resolutions naturally identify former...

We obtain bounds for the minimum and maximum mass/radius ratio of a stable, charged, spherically symmetric compact object in $D$-dimensional space-time framework general relativity, presence dark energy. The total energy, including gravitational component, stability objects with is also investigated. energy condition leads to representation mass radius charged terms charge vacuum only. As applied electron four-dimensional case, this procedure allows one re-obtain classical from purely...

The existence of both a minimum mass and density in nature, the presence positive cosmological constant, is one most intriguing results classical general relativity. These follow rigorously from Buchdahl inequalities four-dimensional de Sitter space. In this work, we obtain generalized arbitrary space–time dimensions with $$\Lambda \ne 0$$ consider anti-de cases. dependence on D, number dimensions, maximum masses for stable spherical objects explicitly obtained. analysis then extended to...

We outline a new model in which generalised uncertainty relations are obtained without modified commutation relations. While existing models introduce phase space volumes for the canonical degrees of freedom, we freedom background geometry. The is therefore enlarged but remains Euclidean. spatial treated as genuinely quantum object, with an associated state vector, and naturally gives rise to extended principle (EGUP). Importantly, this approach solves (or rather, evades) well known problems...

We numerically solve the equations of motion (EOM) for two models circular cosmic string loops with windings in a simply connected internal space. Since cannot be topologically stabilized, stability must achieved (if at all) dynamically. As toy realistic compactifications, we consider on small section $$\mathbb {R}^2$$ , which is valid as an approximation to any manifold if winding radius sufficiently small, and $$S^2$$ constant $$\mathcal {R}$$ . then use Kosambi–Cartan–Chern (KCC) theory...

We consider Kasner-type static, cylindrically symmetric interior string solutions in the $f\left(R,L_m\right)$ theory of modified gravity. The physical properties are described by an anisotropic energy-momentum tensor satisfying condition $T_t^t=T_z^z$; that is, energy density along $z$-axis is equal to minus tension. As a first step our study we obtain gravitational field equations for general metric, and then which metric components have power law dependence on radial coordinate $r$....

In three spatial dimensions, the Compton wavelength $(R_C \propto M^{-1}$) and Schwarzschild radius $(R_S M$) are dual under transformation $M \rightarrow M_{P}^2/M$, where $M_{P}$ is Planck mass. This suggests that there a fundamental link -- termed Black Hole Uncertainty Principle or Compton-Schwarzschild correspondence between elementary particles in &lt; M_{P}$ regime black holes &gt; regime. presence of $n$ extra compactified on some scale $R_E$, one expects $R_S M^{1/(1+n)}$ for $R...

We propose a new method for generating generalized uncertainty relations (GURs) including the principle (GUP), extended (EUP), and (EGUP), previously proposed in quantum gravity literature, without modifying Heisenberg algebra. Our approach is compatible with equivalence principle, local Poincar´e invariance relativistic limit, thus circumventing many of problems associated GURs derived from modified commutation relations. In particular, it does not require existence nonlinear additional law...

Gedanken experiments in quantum gravity motivate generalised uncertainty relations (GURs) implying deviations from the standard statistics close to Planck scale. These have been extensively investigated for non-spin part of wave function, but existing models tacitly assume that spin states remain unaffected by quantisation background which matter propagates. Here, we explore a new model nonlocal geometry Planck-scale smearing classical points generates GURs angular momentum. These, turn,...

In three spatial dimensions, the Compton wavelength $(R_C \propto M^{-1}$) and Schwarzschild radius $(R_S M$) are dual under transformation $M \rightarrow M_{P}^2/M$, where $M_{P}$ is Planck mass. This suggests that there could be a fundamental link -- termed Black Hole Uncertainty Principle or Compton-Schwarzschild correspondence between elementary particles with < M_{P}$ black holes in > regime. presence of $n$ extra compactified on some scale $R_E$ exceeding length $R_P$, one expects $R_S...

We consider the nature of quantum properties in non-relativistic mechanics (QM) and relativistic field theories, examine connection between formal quantization schemes intuitive notions wave-particle duality. Based on map classical Poisson brackets their associated commutators, such give rise to states obeying canonical dispersion relations, obtained by substituting de Broglie relations into relevant (classical) energy-momentum relation. In QM, this yields a relation involving ℏ but not c,...

We propose a mechanism for the creation of cosmic string loops with dynamically stabilised windings in internal space. Assuming velocity correlations regime post-inflationary epoch, such are seen to arise naturally networks prior loop formation. The angular momentum compact space may then be sufficient ensure that remain stable after chops off from network, even if manifold is simply connected. For concreteness we embed our model Klebanov-Strassler geometry, which provides natural brane...

We derive upper and lower limits for the mass–radius ratio of spin-fluid spheres in Einstein–Cartan theory, with matter satisfying a linear barotropic equation state, presence cosmological constant. Adopting spherically symmetric interior geometry, we obtain generalized continuity Tolman–Oppenheimer–Volkoff equations Weyssenhoff spin fluid hydrostatic equilibrium, expressed terms effective mass, density pressure, all which contain additional contributions from spin. The Buchdahl inequality,...

In this short note we show how the Generalised Uncertainty Principle (GUP) and Extended (EUP), two of most common generalised uncertainty relations proposed in quantum gravity literature, can be derived within context canonical theory, without need for modified commutation relations. A GUP-type relation naturally emerges when standard position operator is replaced by an appropriate Positive Operator Valued Measure (POVM), representing a finite-accuracy measurement that localises wave packet...

In the early-mid 20th century Dirac and Zel'dovich were among first scientists to suggest an intimate connection between cosmology atomic physics. Though a revolutionary proposal for its time, Dirac's Large Number Hypothesis (1937) adopted standard assumption of day, namely, non-existence cosmological constant term (Λ = 0). As result, implementation necessitated extreme violence theory general relativity – something few physicists prepared sacrifice in favour 'numerology' requiring...

We introduce a dark energy-modified minimum length uncertainty relation (DE-MLUR) or energy principle (DE-UP) for short. The new is structurally similar to the MLUR introduced by Károlyházy (1968), and reproduced Ng van Dam (1994) using alternative arguments, but with number of important differences. These include dependence on de Sitter horizon, which may be expressed in terms cosmological constant as l dS ∼ 1 / Λ . Applying DE-UP both charged neutral particles, we obtain estimates two...