1,390 research outputs found

    Cosmological Relativity: A General-Relativistic Theory for the Accelerating Expanding Universe

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    Recent observations of distant supernovae imply, in defiance of expectations, that the universe growth is accelerating, contrary to what has always been assumed that the expansion is slowing down due to gravity. In this paper a general-relativistic cosmological theory that gives a direct relationship between distances and redshifts in an expanding universe is presented. The theory is actually a generalization of Hubble's law taking gravity into account by means of Einstein's theory of general relativity. The theory predicts that the universe can have three phases of expansion, decelerating, constant and accelerating, but it is shown that at present the first two cases are excluded, although in the past it had experienced them. Our theory shows that the universe now is definitely in the stage of accelerating expansion, confirming the recent experimental results

    Covalently Binding the Photosystem I to Carbon Nanotubes

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    We present a chemical route to covalently couple the photosystem I (PS I) to carbon nanotubes (CNTs). Small linker molecules are used to connect the PS I to the CNTs. Hybrid systems, consisting of CNTs and the PS I, promise new photo-induced transport phenomena due to the outstanding optoelectronic properties of the robust cyanobacteria membrane protein PS I

    Carmeli's accelerating universe is spatially flat without dark matter

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    Carmeli's 5D brane cosmology has been applied to the expanding accelerating universe and it has been found that the distance redshift relation will fit the data of the high-z supernova teams without the need for dark matter. Also the vacuum energy contribution to gravity indicates that the universe is asymptotically expanding towards a spatially flat state, where the total mass/energy density tends to unity.Comment: 4 pages, 5 figures, accepted for publication in Int. J. Theor. Physics, this paper is based on an invited talk at FFP6, Udine, Italy, Sept 200

    Unitary representations of super Lie groups and applications to the classification and multiplet structure of super particles

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    It is well known that the category of super Lie groups (SLG) is equivalent to the category of super Harish-Chandra pairs (SHCP). Using this equivalence, we define the category of unitary representations (UR's) of a super Lie group. We give an extension of the classical inducing construction and Mackey imprimitivity theorem to this setting. We use our results to classify the irreducible unitary representations of semidirect products of super translation groups by classical Lie groups, in particular of the super Poincar\'e groups in arbitrary dimension. Finally we compare our results with those in the physical literature on the structure and classification of super multiplets.Comment: 55 pages LaTeX, some corrections added after comments by Prof. Pierre Delign

    Testing Cosmological General Relativity against high redshift observations

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    Several key relations are derived for Cosmological General Relativity which are used in standard observational cosmology. These include the luminosity distance, angular size, surface brightness and matter density. These relations are used to fit type Ia supernova (SNe Ia) data, giving consistent, well behaved fits over a broad range of redshift 0.1<z<20.1 < z < 2. The best fit to the data for the local density parameter is Ωm=0.0401±0.0199\Omega_{m} = 0.0401 \pm 0.0199. Because Ωm\Omega_{m} is within the baryonic budget there is no need for any dark matter to account for the SNe Ia redshift luminosity data. From this local density it is determined that the redshift where the universe expansion transitions from deceleration to acceleration is zt=1.0950.155+0.264z_{t}= 1.095 {}^{+0.264}_{-0.155}. Because the fitted data covers the range of the predicted transition redshift ztz_{t}, there is no need for any dark energy to account for the expansion rate transition. We conclude that the expansion is now accelerating and that the transition from a closed to an open universe occurred about 8.54Gyr8.54 {\rm Gyr} ago.Comment: Rewritten, improved and revised the discussion. This is now a combined paper of the former version and the Addendu

    Constructing Extremal Compatible Quantum Observables by Means of Two Mutually Unbiased Bases

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    We describe a particular class of pairs of quantum observables which are extremal in the convex set of all pairs of compatible quantum observables. The pairs in this class are constructed as uniformly noisy versions of two mutually unbiased bases (MUB) with possibly different noise intensities affecting each basis. We show that not all pairs of MUB can be used in this construction, and we provide a criterion for determining those MUB that actually do yield extremal compatible observables. We apply our criterion to all pairs of Fourier conjugate MUB, and we prove that in this case extremality is achieved if and only if the quantum system Hilbert space is odd-dimensional. Remarkably, this fact is no longer true for general non-Fourier conjugate MUB, as we show in an example. Therefore, the presence or the absence of extremality is a concrete geometric manifestation of MUB inequivalence, that already materializes by comparing sets of no more than two bases at a time

    Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic limit

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    It has been recently observed for palladium and gold nanoparticles, that the magnetic moment at constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples with size smaller than 2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so small samples up to so high temperatures has been explained as due to blocking of local magnetic moment by giant magnetic anisotropies. In this report we show, by analysing the anisotropy of thiol capped gold films, that the orbital momentum induced at the surface conduction electrons is crucial to understand the observed giant anisotropy. The orbital motion is driven by localised charge and/or spin through spin orbit interaction, that reaches extremely high values at the surfaces. The induced orbital moment gives rise to an effective field of the order of 103 T that is responsible of the giant anisotropy.Comment: 15 pages, 2 figures, submitted to PR

    Alignment and algebraically special tensors in Lorentzian geometry

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    We develop a dimension-independent theory of alignment in Lorentzian geometry, and apply it to the tensor classification problem for the Weyl and Ricci tensors. First, we show that the alignment condition is equivalent to the PND equation. In 4D, this recovers the usual Petrov types. For higher dimensions, we prove that, in general, a Weyl tensor does not possess aligned directions. We then go on to describe a number of additional algebraic types for the various alignment configurations. For the case of second-order symmetric (Ricci) tensors, we perform the classification by considering the geometric properties of the corresponding alignment variety.Comment: 19 pages. Revised presentatio

    5D gravitational waves from complexified black rings

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    In this paper we construct and briefly study the 5D time-dependent solutions of general relativity obtained via double analytic continuation of the black hole (Myers-Perry) and of the black ring solutions with a double (Pomeransky-Senkov) and a single rotation (Emparan-Reall). The new solutions take the form of a generalized Einstein-Rosen cosmology representing gravitational waves propagating in a closed universe. In this context the rotation parameters of the rings can be interpreted as the extra wave polarizations, while it is interesting to state that the waves obtained from Myers-Perry Black holes exhibit an extra boost-rotational symmetry in higher dimensions which signals their better behavior at null infinity. The analogue to the C-energy is analyzed.Comment: 18 pages, 4 figures. References added, introduction and conclusions are amended, some issues related to singularity structure and symmetries are discussed. Matches the print version to appear in JHE

    Extreme phase and rotated quadrature measurements

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    We determine the extreme points of the convex set of covariant phase observables. Such extremals describe the best phase parameter measurements of laser light - the best in the sense that they are free from classical randomness due to fluctuations in the measuring procedure. We also characterize extreme fuzzy rotated quadratures
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