A Review of Redshift and Its Interpretation in Cosmology and Astrophysics”
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Frame Covariance and Fine Tuning in Inflationary Cosmology
FRAME COVARIANCE AND FINE TUNING IN INFLATIONARY COSMOLOGY A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering 2019 By Sotirios Karamitsos School of Physics and Astronomy Contents Abstract 8 Declaration 9 Copyright Statement 10 Acknowledgements 11 1 Introduction 13 1.1 Frames in Cosmology: A Historical Overview . 13 1.2 Modern Cosmology: Frames and Fine Tuning . 15 1.3 Outline . 17 2 Standard Cosmology and the Inflationary Paradigm 20 2.1 General Relativity . 20 2.2 The Hot Big Bang Model . 25 2.2.1 The Expanding Universe . 26 2.2.2 The Friedmann Equations . 29 2.2.3 Horizons and Distances in Cosmology . 33 2.3 Problems in Standard Cosmology . 34 2.3.1 The Flatness Problem . 35 2.3.2 The Horizon Problem . 36 2 2.4 An Accelerating Universe . 37 2.5 Inflation: More Questions Than Answers? . 40 2.5.1 The Frame Problem . 41 2.5.2 Fine Tuning and Initial Conditions . 45 3 Classical Frame Covariance 48 3.1 Conformal and Weyl Transformations . 48 3.2 Conformal Transformations and Unit Changes . 51 3.3 Frames in Multifield Scalar-Tensor Theories . 55 3.4 Dynamics of Multifield Inflation . 63 4 Quantum Perturbations in Field Space 70 4.1 Gauge Invariant Perturbations . 71 4.2 The Field Space in Multifield Inflation . 74 4.3 Frame-Covariant Observable Quantities . 78 4.3.1 The Potential Slow-Roll Hierarchy . 81 4.3.2 Isocurvature Effects in Two-Field Models . 83 5 Fine Tuning in Inflation 88 5.1 Initial Conditions Fine Tuning . -
PDF Solutions
Solutions to exercises Solutions to exercises Exercise 1.1 A‘stationary’ particle in anylaboratory on theEarth is actually subject to gravitationalforcesdue to theEarth andthe Sun. Thesehelp to ensure that theparticle moveswith thelaboratory.Ifstepsweretaken to counterbalance theseforcessothatthe particle wasreally not subject to anynet force, then the rotation of theEarth andthe Earth’sorbital motionaround theSun would carry thelaboratory away from theparticle, causing theforce-free particle to followacurving path through thelaboratory.Thiswouldclearly show that the particle didnot have constantvelocity in the laboratory (i.e.constantspeed in a fixed direction) andhence that aframe fixed in the laboratory is not an inertial frame.More realistically,anexperimentperformed usingthe kind of long, freely suspendedpendulum known as a Foucaultpendulum couldreveal the fact that a frame fixed on theEarth is rotating andthereforecannot be an inertial frame of reference. An even more practical demonstrationisprovidedbythe winds,which do not flowdirectly from areas of high pressure to areas of lowpressure because of theEarth’srotation. - Exercise 1.2 TheLorentzfactor is γ(V )=1/ 1−V2/c2. (a) If V =0.1c,then 1 γ = - =1.01 (to 3s.f.). 1 − (0.1c)2/c2 (b) If V =0.9c,then 1 γ = - =2.29 (to 3s.f.). 1 − (0.9c)2/c2 Notethatitisoften convenient to write speedsinterms of c instead of writingthe values in ms−1,because of thecancellation between factorsofc. ? @ AB Exercise 1.3 2 × 2 M = Theinverse of a matrix CDis ? @ 1 D −B M −1 = AD − BC −CA. Taking A = γ(V ), B = −γ(V )V/c, C = −γ(V)V/c and D = γ(V ),and noting that AD − BC =[γ(V)]2(1 − V 2/c2)=1,wehave ? @ γ(V )+γ(V)V/c [Λ]−1 = . -
Measurement of the Speed of Gravity
Measurement of the Speed of Gravity Yin Zhu Agriculture Department of Hubei Province, Wuhan, China Abstract From the Liénard-Wiechert potential in both the gravitational field and the electromagnetic field, it is shown that the speed of propagation of the gravitational field (waves) can be tested by comparing the measured speed of gravitational force with the measured speed of Coulomb force. PACS: 04.20.Cv; 04.30.Nk; 04.80.Cc Fomalont and Kopeikin [1] in 2002 claimed that to 20% accuracy they confirmed that the speed of gravity is equal to the speed of light in vacuum. Their work was immediately contradicted by Will [2] and other several physicists. [3-7] Fomalont and Kopeikin [1] accepted that their measurement is not sufficiently accurate to detect terms of order , which can experimentally distinguish Kopeikin interpretation from Will interpretation. Fomalont et al [8] reported their measurements in 2009 and claimed that these measurements are more accurate than the 2002 VLBA experiment [1], but did not point out whether the terms of order have been detected. Within the post-Newtonian framework, several metric theories have studied the radiation and propagation of gravitational waves. [9] For example, in the Rosen bi-metric theory, [10] the difference between the speed of gravity and the speed of light could be tested by comparing the arrival times of a gravitational wave and an electromagnetic wave from the same event: a supernova. Hulse and Taylor [11] showed the indirect evidence for gravitational radiation. However, the gravitational waves themselves have not yet been detected directly. [12] In electrodynamics the speed of electromagnetic waves appears in Maxwell equations as c = √휇0휀0, no such constant appears in any theory of gravity. -
3 the Friedmann-Robertson-Walker Metric
3 The Friedmann-Robertson-Walker metric 3.1 Three dimensions The most general isotropic and homogeneous metric in three dimensions is similar to the two dimensional result of eq. (43): dr2 ds2 = a2 + r2dΩ2 ; dΩ2 = dθ2 + sin2 θdφ2 ; k = 0; 1 : (46) 1 kr2 − The angles φ and θ are the usual azimuthal and polar angles of spherical coordinates, with θ [0; π], φ [0; 2π). As before, the parameter k can take on three different values: for k = 0, 2 2 the above line element describes ordinary flat space in spherical coordinates; k = 1 yields the metric for S , with constant positive curvature, while k = 1 is AdS and has constant 3 − 3 negative curvature. As in the two dimensional case, the change of variables r = sin χ (k = 1) or r = sinh χ (k = 1) makes the global nature of these manifolds more apparent. For example, − for the k = 1 case, after defining r = sin χ, the line element becomes ds2 = a2 dχ2 + sin2 χdθ2 + sin2 χ sin2 θdφ2 : (47) This is equivalent to writing ds2 = dX2 + dY 2 + dZ2 + dW 2 ; (48) where X = a sin χ sin θ cos φ ; Y = a sin χ sin θ sin φ ; Z = a sin χ cos θ ; W = a cos χ ; (49) which satisfy X2 + Y 2 + Z2 + W 2 = a2. So we see that the k = 1 metric corresponds to a 3-sphere of radius a embedded in 4-dimensional Euclidean space. One also sees a problem with the r = sin χ coordinate: it does not cover the whole sphere. -
Stability of Narrow-Band Filter Radiometers in the Solar-Reflective Range
Stability of Narrow-Band Filter Radiometers in the Solar-Reflective Range D. E. Flittner and P. N. Slater Optical Sciences Center, University of Arizona, Tucson, AZ 85721 ABSTRACT:We show that the calibration, with respect to a continuous-spech.umsource, and the stability of radiometers using filters of about 10 nm full width, half maximum (FWHM) in the wavelength interval 0.4 to 1.0 pm, can change by several percent if the filters change in position by only a few nanometres. The cause is the shifts of the passbands of the filters into or out of Fraunhofer lines in the solar spectrum or water vapor or oxygen absorption bands in the Earth's atmosphere. These shifts can be due to ageing accompanied by the absorption of water vapor into the filter or temperature changes for field radiometers, or to outgassing and possibly high energy solar irradiation for space instru- ments such as the MODerate resolution Imaging Spectrometer - Nadir (MODIS-N) proposed for the Earth Observing System. INTRODUCTION sun, but can lead to errors in moderate to high spectral reso- lution measurements of the Earth-atmosphere system if their T IS WELL KNOWN that satellite multispectral sensor data in Ithe visible and near infrared are acquired with spectral band- effect is not taken into account. The concern is that the narrow- widths from about 40 nm (System Probatoire &Observation de band filters in a radiometer may shift, causing them to move la Terre (SPOT) band 2) and 70 nm (Thematic Mapper (TM)band into or out of a region containing a Fraunhofer line, thereby 3) to about 200 and 400 nm (Multispectral Scanner System (MSS) causing a noticeable change in the radiometer output. -
Baryogenesis in a CP Invariant Theory That Utilizes the Stochastic Movement of Light fields During Inflation
Baryogenesis in a CP invariant theory Anson Hook School of Natural Sciences Institute for Advanced Study Princeton, NJ 08540 June 12, 2018 Abstract We consider baryogenesis in a model which has a CP invariant Lagrangian, CP invariant initial conditions and does not spontaneously break CP at any of the minima. We utilize the fact that tunneling processes between CP invariant minima can break CP to implement baryogenesis. CP invariance requires the presence of two tunneling processes with opposite CP breaking phases and equal probability of occurring. In order for the entire visible universe to see the same CP violating phase, we consider a model where the field doing the tunneling is the inflaton. arXiv:1508.05094v1 [hep-ph] 20 Aug 2015 1 1 Introduction The visible universe contains more matter than anti-matter [1]. The guiding principles for gener- ating this asymmetry have been Sakharov’s three conditions [2]. These three conditions are C/CP violation • Baryon number violation • Out of thermal equilibrium • Over the years, counter examples have been found for Sakharov’s conditions. One can avoid the need for number violating interactions in theories where the negative B L number is stored − in a sector decoupled from the standard model, e.g. in right handed neutrinos as in Dirac lep- togenesis [3, 4] or in dark matter [5]. The out of equilibrium condition can be avoided if one uses spontaneous baryogenesis [6], where a chemical potential is used to create a non-zero baryon number in thermal equilibrium. However, these models still require a C/CP violating phase or coupling in the Lagrangian. -
Gold T. Rotating Neutron Stars As the Origin of the Pulsating Radio Sources
CC/NUMBER 8 ® FEBRUARY 22, 1993 This Week's Citation Classic Gold T. Rotating neutron stars as the origin of the pulsating radio sources. Nature 218:731-2, 1968; and Gold T. Rotating neutron stars and the nature of pulsars. Nature 221:25-7, 1969. [Center for Radiophysics and Space Research: and Cornell-Sydney University Astronomy Center. Cornell University, Ithaca. NY] Enigmatic, rapidly pulsating radio sources were preferred to attribute these sources to interpreted as rotating beacons sweeping over distant galaxies, not to stellar objects. the Earth, radiating out from rapidly rotating, The pulsars now seemed to repre- extremely collapsed stars ("neutron stars"). Nu- merous detailed predictions followed from this sent just the stellar objects I had dis- model, and all were soon verified. The model cussed then. Calculations existed for also accounted closely for the previously unex- the collapsed "neutron stars" that in- plained luminosity of the Crab Nebula. [The dicated approximately their size, as SCI® indicates that these papers have been small as a few kilometers, and their cited in more than 240 and 150 publications, mass, on the order of a solar mass.4 respectively.] Astronomers generally thought that even if they existed, they could never be discovered. However hot, a star so small could not be seen at astronomi- The Nature of Pulsars cal distances. But they had not con- sidered the energy concentration re- Thomas Gold sulting from the collapse: enormous Center for Radiophysics magnetic field strengths and a spin and Space Research energy quite comparable with the en- Cornell University tire content of nuclear energy of the Ithaca, NY 14853 star before its collapse. -
Dark Matter and the Early Universe: a Review Arxiv:2104.11488V1 [Hep-Ph
Dark matter and the early Universe: a review A. Arbey and F. Mahmoudi Univ Lyon, Univ Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique des 2 Infinis de Lyon, UMR 5822, 69622 Villeurbanne, France Theoretical Physics Department, CERN, CH-1211 Geneva 23, Switzerland Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France Abstract Dark matter represents currently an outstanding problem in both cosmology and particle physics. In this review we discuss the possible explanations for dark matter and the experimental observables which can eventually lead to the discovery of dark matter and its nature, and demonstrate the close interplay between the cosmological properties of the early Universe and the observables used to constrain dark matter models in the context of new physics beyond the Standard Model. arXiv:2104.11488v1 [hep-ph] 23 Apr 2021 1 Contents 1 Introduction 3 2 Standard Cosmological Model 3 2.1 Friedmann-Lema^ıtre-Robertson-Walker model . 4 2.2 A quick story of the Universe . 5 2.3 Big-Bang nucleosynthesis . 8 3 Dark matter(s) 9 3.1 Observational evidences . 9 3.1.1 Galaxies . 9 3.1.2 Galaxy clusters . 10 3.1.3 Large and cosmological scales . 12 3.2 Generic types of dark matter . 14 4 Beyond the standard cosmological model 16 4.1 Dark energy . 17 4.2 Inflation and reheating . 19 4.3 Other models . 20 4.4 Phase transitions . 21 5 Dark matter in particle physics 21 5.1 Dark matter and new physics . 22 5.1.1 Thermal relics . 22 5.1.2 Non-thermal relics . -
Hypercomplex Algebras and Their Application to the Mathematical
Hypercomplex Algebras and their application to the mathematical formulation of Quantum Theory Torsten Hertig I1, Philip H¨ohmann II2, Ralf Otte I3 I tecData AG Bahnhofsstrasse 114, CH-9240 Uzwil, Schweiz 1 [email protected] 3 [email protected] II info-key GmbH & Co. KG Heinz-Fangman-Straße 2, DE-42287 Wuppertal, Deutschland 2 [email protected] March 31, 2014 Abstract Quantum theory (QT) which is one of the basic theories of physics, namely in terms of ERWIN SCHRODINGER¨ ’s 1926 wave functions in general requires the field C of the complex numbers to be formulated. However, even the complex-valued description soon turned out to be insufficient. Incorporating EINSTEIN’s theory of Special Relativity (SR) (SCHRODINGER¨ , OSKAR KLEIN, WALTER GORDON, 1926, PAUL DIRAC 1928) leads to an equation which requires some coefficients which can neither be real nor complex but rather must be hypercomplex. It is conventional to write down the DIRAC equation using pairwise anti-commuting matrices. However, a unitary ring of square matrices is a hypercomplex algebra by definition, namely an associative one. However, it is the algebraic properties of the elements and their relations to one another, rather than their precise form as matrices which is important. This encourages us to replace the matrix formulation by a more symbolic one of the single elements as linear combinations of some basis elements. In the case of the DIRAC equation, these elements are called biquaternions, also known as quaternions over the complex numbers. As an algebra over R, the biquaternions are eight-dimensional; as subalgebras, this algebra contains the division ring H of the quaternions at one hand and the algebra C ⊗ C of the bicomplex numbers at the other, the latter being commutative in contrast to H. -
Fraunhofer Lidar Prototype in the Green Spectral Region for Atmospheric Boundary Layer Observations
Remote Sens. 2013, 5, 6079-6095; doi:10.3390/rs5116079 OPEN ACCESS Remote Sensing ISSN 2072-4292 www.mdpi.com/journal/remotesensing Article Fraunhofer Lidar Prototype in the Green Spectral Region for Atmospheric Boundary Layer Observations Songhua Wu *, Xiaoquan Song and Bingyi Liu Ocean Remote Sensing Institute, Ocean University of China, 238 Songling Road, Qingdao 266100, China; E-Mails: [email protected] (X.S.); [email protected] (B.L.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +86-532-6678-2573. Received: 8 October 2013; in revised form: 27 October 2013 / Accepted: 13 November 2013 / Published: 18 November 2013 Abstract: A lidar detects atmospheric parameters by transmitting laser pulse to the atmosphere and receiving the backscattering signals from molecules and aerosol particles. Because of the small backscattering cross section, a lidar usually uses the high sensitive photomultiplier and avalanche photodiode as detector and uses photon counting technology for collection of weak backscatter signals. Photon Counting enables the capturing of extremely weak lidar return from long distance, throughout dark background, by a long time accumulation. Because of the strong solar background, the signal-to-noise ratio of lidar during daytime could be greatly restricted, especially for the lidar operating at visible wavelengths where solar background is prominent. Narrow band-pass filters must therefore be installed in order to isolate solar background noise at wavelengths close to that of the lidar receiving channel, whereas the background light in superposition with signal spectrum, limits an effective margin for signal-to-noise ratio (SNR) improvement. This work describes a lidar prototype operating at the Fraunhofer lines, the invisible band of solar spectrum, to achieve photon counting under intense solar background. -
An Analysis of Gravitational Redshift from Rotating Body
An analysis of gravitational redshift from rotating body Anuj Kumar Dubey∗ and A K Sen† Department of Physics, Assam University, Silchar-788011, Assam, India. (Dated: July 29, 2021) Gravitational redshift is generally calculated without considering the rotation of a body. Neglect- ing the rotation, the geometry of space time can be described by using the spherically symmetric Schwarzschild geometry. Rotation has great effect on general relativity, which gives new challenges on gravitational redshift. When rotation is taken into consideration spherical symmetry is lost and off diagonal terms appear in the metric. The geometry of space time can be then described by using the solutions of Kerr family. In the present paper we discuss the gravitational redshift for rotating body by using Kerr metric. The numerical calculations has been done under Newtonian approximation of angular momentum. It has been found that the value of gravitational redshift is influenced by the direction of spin of central body and also on the position (latitude) on the central body at which the photon is emitted. The variation of gravitational redshift from equatorial to non - equatorial region has been calculated and its implications are discussed in detail. I. INTRODUCTION from principle of equivalence. Snider in 1972 has mea- sured the redshift of the solar potassium absorption line General relativity is not only relativistic theory of grav- at 7699 A˚ by using an atomic - beam resonance - scat- itation proposed by Einstein, but it is the simplest theory tering technique [5]. Krisher et al. in 1993 had measured that is consistent with experimental data. Predictions of the gravitational redshift of Sun [6]. -
Cosmology Slides
Inhomogeneous cosmologies George Ellis, University of Cape Town 27th Texas Symposium on Relativistic Astrophyiscs Dallas, Texas Thursday 12th December 9h00-9h45 • The universe is inhomogeneous on all scales except the largest • This conclusion has often been resisted by theorists who have said it could not be so (e.g. walls and large scale motions) • Most of the universe is almost empty space, punctuated by very small very high density objects (e.g. solar system) • Very non-linear: / = 1030 in this room. Models in cosmology • Static: Einstein (1917), de Sitter (1917) • Spatially homogeneous and isotropic, evolving: - Friedmann (1922), Lemaitre (1927), Robertson-Walker, Tolman, Guth • Spatially homogeneous anisotropic (Bianchi/ Kantowski-Sachs) models: - Gödel, Schücking, Thorne, Misner, Collins and Hawking,Wainwright, … • Perturbed FLRW: Lifschitz, Hawking, Sachs and Wolfe, Peebles, Bardeen, Ellis and Bruni: structure formation (linear), CMB anisotropies, lensing Spherically symmetric inhomogeneous: • LTB: Lemaître, Tolman, Bondi, Silk, Krasinski, Celerier , Bolejko,…, • Szekeres (no symmetries): Sussman, Hellaby, Ishak, … • Swiss cheese: Einstein and Strauss, Schücking, Kantowski, Dyer,… • Lindquist and Wheeler: Perreira, Clifton, … • Black holes: Schwarzschild, Kerr The key observational point is that we can only observe on the past light cone (Hoyle, Schücking, Sachs) See the diagrams of our past light cone by Mark Whittle (Virginia) 5 Expand the spatial distances to see the causal structure: light cones at ±45o. Observable Geo Data Start of universe Particle Horizon (Rindler) Spacelike singularity (Penrose). 6 The cosmological principle The CP is the foundational assumption that the Universe obeys a cosmological law: It is necessarily spatially homogeneous and isotropic (Milne 1935, Bondi 1960) Thus a priori: geometry is Robertson-Walker Weaker form: the Copernican Principle: We do not live in a special place (Weinberg 1973).