Search results for "Relativity"
showing 10 items of 1213 documents
Lensing of fast radio bursts: future constraints on primordial black hole density with an extended mass function and a new probe of exotic compact fe…
2018
The discovery of gravitational waves from binary black hole mergers has renewed interest in primordial black holes forming a part of the dark matter density of our Universe. Various tests have been proposed to test this hypothesis. One of the cleanest tests is the lensing of fast radio bursts. In this situation, the presence of a compact object near the line of sight produces two images of the radio burst. If the images are sufficiently separated in time, this technique can constrain the presence of primordial black holes. One can also try to detect the lensed image of the mini-bursts within the main burst. We show that this technique can produce the leading constraints over a wide range in…
Magnetic fields and chiral asymmetry in the early hot universe
2016
In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, consider…
Impact of cosmic inhomogeneities on SNe observations
2009
We study the impact of cosmic inhomogeneities on the interpretation of SNe observations. We build an inhomogeneous universe model that can confront supernova data and yet is reasonably well compatible with the Copernican Principle. Our model combines a relatively small local void, that gives apparent acceleration at low redshifts, with a meatball model that gives sizeable lensing (dimming) at high redshifts. Together these two elements, which focus on different effects of voids on the data, allow the model to mimic the concordance model.
In the realm of the Hubble tension—a review of solutions
2021
The $\Lambda$CDM model provides a good fit to a large span of cosmological data but harbors areas of phenomenology. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the $4-6\sigma$ disagreement between predictions of the Hubble constant $H_0$ by early time probes with $\Lambda$CDM model, and a number of late time, model-independent determinations of $H_0$ from local measurements of distances and redshifts. The high precision and consistency of the data at both ends present strong challenges to the possible solution space and demand a hypothesis with en…
The body-mind problem from a personality relativity theory approach: (Relativity of personality)
2012
The body-mind problem is here posed fromthe General Factor of Personality Theory and mathematically presented as a relativity theory: 1. A two-level-invariant model; 2. The transformation equation between both levels. On a hand, the investigation of personality dynamicsas a consequenceof a stimulant drug provides a system of two coupled differential equations, which adapts to both biological (body) and psychological (mind)levels ofdescription. On the other hand, a system of two coupled partial differential equations is here deduced as the transformation model between the biological and psychological levels. Both models are presented and validated in this paper. The experimental design to va…
Dynamical formation and stability of fermion-boson stars
2020
Gravitationally bound structures composed by fermions and scalar particles known as fermion-boson stars are regular and static configurations obtained by solving the coupled Einstein-Klein-Gordon-Euler (EKGE) system. In this work, we discuss one possible scenario through which these fermion-boson stars may form by solving numerically the EKGE system under the simplifying assumption of spherical symmetry. Our initial configurations assume an already existing neutron star surrounded by an accreting cloud of a massive and complex scalar field. The results of our simulations show that once part of the initial scalar field is expelled via gravitational cooling the system gradually oscillates aro…
Non-Markovian master equation for the XX central spin model
2008
The non-Markovian correlated projection operator technique is applied to the model of a central spin coupled to a spin bath through non uniform XX Heisenberg coupling. The second order results of the Nakajima-Zwanzig and of the time-convolutionless methods are compared with the exact solution considering a fully polarized initial bath state.
Critical path analysis in the network with fuzzy activity times
2001
A natural generalization of the criticality notion in a network with fuzzy activity times is given. It consists in direct application of the extension principle of Zadeh to the notion of criticality of a path (an activity, an event) treated as a function of the activities duration times in the network. There are shown some relations between the notion of fuzzy criticality, introduced in the paper, and the notion of interval criticality (criticality in the network with interval activity times) proposed by the authors in another paper. Two methods of calculation of the path degree of criticality (according to the proposed concept of fuzzy criticality) are presented.
The interaction of language and thought in children's language acquisition: a crosslinguistic study
1997
The purpose of this research was to investigate the potential interaction of conceptual representations and linguistic systems in the process of language acquisition. Language–thought interactions were studied in 80 American, 48 Finnish and 48 Polish preschool children. The research focused on the conceptual and linguistic development of space and time. The spatial and temporal conceptual tasks were designed to measure the transition from experiential to inferential knowledge of space/time representations. In the linguistic domain, comprehension and production tests were used to evaluate the children's capacity to understand mono- and bi-referential location in space and time, where mono-re…
From subatomic to immense: About the possible influence of the Theory of Relativity and Quantum Mechanics in the fantastic
2015
The fantastic is based on three pillars: reality, the impossible and fear. Theoretical physics is a branch of science that has deeply studied reality, from the subatomic world to the immensity of outer space. In this article, we want to study how the Theory of Relativity and the Quantum Mechanics have influenced the configuration of the fantastic, and in addition, we want to verify if these branches of physics are capable of explaining certain fantastic phenomena.