DOCSLIB.ORG

Cosmology 101 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cosmology 101 2 COSMOLOGY 101 2 Chris Pearson : RAL Space July 2015 COSMOLOGY 1 How did the Universe Begin ? 1 How old is the Universe ? 1 How big is the Universe ? 1 Where are we in the Universe ? 1 What is the Universe made of ? 1 Will the Universe end ? 2 COSMOLOGY 1 Our Universe is flat and infinite 1 The expansion of the Universe is expanding 1 The Universe began in a hot Big Bang Ho = 67.3 ± 0.012 km/s/Mpc τage = 13.81 ± 0.05 Gyr ΩΛ,o = 0.685 ± 0.017 Ωm,o = 0.315 ± 0.016 ΩDM,o = 0.2662 ± 0.016 Ωb,o = 0.0487 ± 0.00027 3 A Very Brief History of Time 4 The Redshift Frequency increasing Frequency decreasing Wavelength decreasing Wavelength increasing Wave crests get closer together Wave crests get further apart Colour gets BLUER = BLUESHIFT Colour gets REDDER = REDSHIFT 5 The Redshift ! Δν Δλ ν −ν λ − λ v z = = = e o = o e ≈ υ << c ν λ ν λ c ! o e o e for! λe λo ! νe λo -0.2 + z = ≡ The Redshift νo λe -0.4 ! 1 -0.6 )) ν ! (F -0.8 (Flux -1 lg -1.2 Cirrus Spectrum -1.4 -1.6 6 8 10 12 14 16 wavelength (µm) 6 The Redshift Δν Δλ ν ❍ Doppler Redshift z = = = e − ν λ ν ! o e o 1 ! ! ! ! ν + v c c + v v ❍ Special Relativistic Redshift + z = e = ! = ! ≈ υ << c ν − v c c − v c ! o 1 / 1 for! 1 / ! ! ❍ Cosmological Redshift Hubble’s Law v = cz = Hod ! §. Correct interpretation of Cosmological Redshift of galaxies is NOT a Doppler shift. §. Wave fronts expand with the expanding Universe, stretching the photon wavelength. 7 The Redshift Cosmological Redshift λ R t + z ≡ = ( o ) λ0 R t ! e ( e ) 1Cosmological explanation: Redshift - natural consequence since R(t) is an increasing function of time !Wavefronts expand with the expanding Universe, stretching the photon wavelength. R(to) λo λe R(te) 8 A Very Brief History of Time THE HOT BIG BANG: How does the temperature of the early Universe evolve ? Redshift Wiens Law λ o Ro λ R T = RT = = (1+ z) maxT = constant o o λ R Energy density of radiation 4 2 ε = aT = ρc 2 ρ Friedmann Equation R 8πG 2 = R 3 ! $ -1/4 32πGa -1/2 10 -1/2 T = # 2 & t ≈1.5x10 t " 3c % = Radiation constant a = Newton’s Gravitational Constant G = speed of light c Temperature evolution in early Universe depends ONLY on Nature’s fundamental constants! 9 A Very Brief History of Time t=0 10-43s 10-35s 10-12s 10-6s 10-4s 0.01s 1s 4s 3mins 3x105yrs 107yrs 109yrs 1010yrs T=∞ 1031K 1027K 1015K 1013K 1012K 1011K 1010K 5x109K 109K 3000K 300K 30K 2.73K Dark Ages q+ He W± µ+ ν ? o Z q- µ-­‐ ν ν Matter ν Atoms Clumping Initial Singularity + annihila�on µ -­‐ decouple μ e Planck Time Infla�on E-­‐W Phase Transi�on quark -­‐ an�quark annihila�on Hadron-­‐Lepton Reac�ons ν shi� -­‐> Proton n-­‐p ra�o freezes Primordial NucleosynthesisEpoch of Recombina�on First Stars and Galaxies Epoch (re-­‐ioniza�on) of Galaxy Forma�on Forma�on of Solar System and Birth of Life 10 It All Started with a Big Bang 11 It All Started with a Big Bang In the Beginning…… Planck Era = 10-43 s 1031 K # → ' % t 0 % % → % Running Time backwards $ R 0 ( Initial singularity - The Creation Event %T → ∞% % % &ρ → ∞) -43 O t < 10 s known as the Planck Era O Quantum Effects become important O Einstein’s Theory of gravity breaks down 12 It All Started with a Big Bang In the Beginning…… Planck Era = 10-43 s 1031 K Quantum fluctuations of spacetime ~ Planck length, are of cosmic magnitude For a particle of mass, m, λ h Scale at which quantum effects become important : Compton Wavelength c = mc Scale at which self gravity becomes important : Schwarzchild Radius 2Gm RS = 2 c λC RS For a particle of mass, mP = the Planck mass λ c ≈RS Compton Wavelength & Schwarzchild Radius are comparable 13 It All Started with a Big Bang In the Beginning…… Planck Era = 10-43 s 1031 K Did the Big Bang …….. Bang?!? Or was it a Quantum Theory of Gravity ? 1. Quantum Gravity 2. Super Gravity 3. Superstrings 4. M-Theory 14 Problems with the Big Bang ? The Inflationary Era = 10-35 s 1027 K 1. THE HORIZON PROBLEM the isotropy of apparent causally disconnected regions of the CMB 2. THE FLATNESS PROBLEM the apparent remarkable closeness of Omega to 1 3. THE RELIC PROBLEM the apparent absence of relics from the Big Bang in our Universe 15 Problems with the Big Bang ? The Inflationary Era = 10-35 s 1027 K 1. THE HORIZON PROBLEM the isotropy of apparent causally disconnected regions of the CMB 2. THE FLATNESS PROBLEM the apparent remarkable closeness of Omega to 1 3. THE RELIC PROBLEM the apparent absence of relics from the Big Bang in our Universe 16 The Horizon Problem The Inflationary Era = 10-35 s 1027 K Cosmological Horizon: measure of distance at a given time from which information can be retrieved into the past: Defines the Observable Universe. t x y 17 The Horizon Problem The Inflationary Era = 10-35 s 1027 K Cosmological Horizon: measure of distance at a given time from which information can be retrieved into the past: Defines the Observable Universe. Cosmic distance from # 2 & 2 2 2 2 % dr 2 θ 2 2θ φ 2 ( Robertson Walker metric dS = c dt -R (t)% 2 + r (d +sin d )( $1-kr ' The Horizon Scale: ∫ tH c d H = R(tH)r = R(tH) 0 dt ≈ 3ctH R(t) Horizon size today: ~ 46 Billion light years 18 The Horizon Problem The Inflationary Era = 10-35 s 1027 K Horizon size today: ~ 46 Billion light years 5 13 Horizon on microwave background: t ~ 3x10 yrs 10 s : 1 million light years ~ 1.3 degrees on the sky 180 degrees O CMB isotropic To is identical to 1 part in 10,000 O Opposite regions appear never to have been in causal contact O But opposite points in CMB are ~ 90 horizon distances apart !! O So how do they know that they should be at the same temperature?? 19 Problems with the Big Bang ? The Inflationary Era = 10-35 s 1027 K 1. THE HORIZON PROBLEM the isotropy of apparent causally disconnected regions of the CMB 2. THE FLATNESS PROBLEM the apparent remarkable closeness of Omega to 1 3. THE RELIC PROBLEM the apparent absence of relics from the Big Bang in our Universe 20 The Flatness Problem The Inflationary Era = 10-35 s 1027 K Planck satellite Observations: The Universe is almost flat today: Ωo~1± 0.02 How about in the past ? 2 ! 2 ρ 2 2 k c R 2 8πG kc Ω 2 kc Ω 2 = H = - 2 = H - 2 -1 = 2 2 !R 3 R R ! R H 2 2 Ω -1 (R H ) t to Evolution of Ω with time = 2 2 Ω -1 (R H ) ! to t Matter dominated Era: 2/3 ∝ 2/3 ⇒ 2 2 ! 2 ∝ -2/3 Ω ! $ ! $ R t R H = R t -1 t t t = # & = # & Radiation dominated Era: Ω " % " % -1 to matter to radiation to 1/2 2 2 ! 2 -1 ! R∝t ⇒ R H = R ∝t 21 The Flatness Problem The Inflationary Era = 10-35 s 1027 K Planck satellite Observations: The Universe is almost flat today: Ωo~1± 0.02 How about in the past ? ! $2/3 ! $ Ω -1 t t t Evolution of Ω with time = # & = # & Ω " % " % -1 to matter to radiation ! to 6 13 ➠ -7 Ma�er Radia�on Equality teq~ 10 yr = 10 s |1-Ω| < 10 ➠ -18 Big Bang Nucleosynthesis tBBN~ 3mins = 180s |1-Ω| < 10 -43 ➠ -63 Planck Time tP ~ 10 s |1-Ω| < 10 Why is the Universe so FLAT ….. fine Tuning FLATNESSto > 1 part in 1060 Why did the Universe not expand - contract back to a big crunch very quickly Why did the Universe not expand so quickly that galaxies and life were unable to form PROBLEM22 Problems with the Big Bang ? The Inflationary Era = 10-35 s 1027 K 1. THE HORIZON PROBLEM the isotropy of apparent causally disconnected regions of the CMB 2. THE FLATNESS PROBLEM the apparent remarkable closeness of Omega to 1 3. THE RELIC PROBLEM the apparent absence of relics from the Big Bang in our Universe 23 The Relic Problem The Inflationary Era = 10-35 s 1027 K PHASE TRANSITION Strong Nuclear Electromagnetic GUT STRENGTH STRENGTH ELECTROWEAK t=10-­‐35s T=1027K TOE -­‐12 t=10 s E=1015GeV T=1015K Weak Nuclear E=102GeV t=10-­‐43s T=1031K E=1019GeV Gravity O At high energies the forces of nature unify O Symmetry ➡ Forces become indistinguishable from each other O Universe cools ➡ temperature drops ➡ symmetry breaks ➡ phase transition O Like water freezing into ice ➡ defects appear on cooling 24 The Relic Problem The Inflationary Era = 10-35 s 1027 K PHASE TRANSITION Strong Nuclear Electromagnetic GUT STRENGTH STRENGTH ELECTROWEAK t=10-­‐35s T=1027K TOE -­‐12 t=10 s E=1015GeV T=1015K Weak Nuclear E=102GeV t=10-­‐43s T=1031K E=1019GeV Gravity O Phase transition ➡ loss of symmetry ➡ topological defects O Predicted for GUT (strong/electroweak unification) t=10-35s, T=1027K, E=1015GeV O Compare with freezing water O different ice nucleation sites O different axes (domains) of symmetry ➡ topological defects 25 The Relic Problem The Inflationary Era = 10-35 s 1027 K PHASE TRANSITION Strong Nuclear Electromagnetic GUT STRENGTH STRENGTH ELECTROWEAK t=10-­‐35s T=1027K TOE -­‐12 t=10 s E=1015GeV T=1015K Weak Nuclear E=102GeV t=10-­‐43s T=1031K E=1019GeV Gravity O 0D point like defects = Magnetic Monopoles (isolated North/South poles) O 1D linear defects = Cosmic Strings O 2D sheet like defects = Textures 26 The Relic Problem The Inflationary Era = 10-35 s 1027 K Magnetic Monopole rest energy ~ 1015GeV ➡ E=mc2 ➡ mass ≡ bacterium O Phase Transition ➡ symmetry breaking ➡ topological defects O Expect one topological defect / horizon distance Horizon distance at tGUT d H = 2ctGUT Number density of Monopoles 1 146 -3 3 ≈10 Mpc d H 2 with energy density mc 161 -3 3 ≈10 GeVMpc d H Monopoles would dominate the energy density and close the Universe by 10-12 s However…… we are here …… so where are the monopoles ???? 27 Problems with the Big Bang ? The Inflationary Era = 10-35 s 1027 K 1.
Load more

Recommended publications
  • Topic 3 Evidence for the Big Bang
    Topic 3 Primordial nucleosynthesis Evidence for the Big Bang ! Back in the 1920s it was generally thought that the Universe was infinite ! However a number of experimental observations started to question this, namely: • Red shift and Hubble’s Law • Olber’s Paradox • Radio sources • Existence of CMBR Red shift and Hubble’s Law ! We have already discussed red shift in the context of spectral lines (Topic 2) ! Crucially Hubble discovered that the recessional velocity (and hence red shift) of galaxies increases linearly with their distance from us according to the famous Hubble Law V = H0d where H0 = 69.3 ±0.8 (km/s)/Mpc and 1/H0 = Age of Universe Olbers’ paradox ! Steady state Universe is: infinite, isotropic or uniform (sky looks the same in all directions), homogeneous (our location in the Universe isn’t special) and is not expanding ! Therefore an observer choosing to look in any direction should eventually see a star ! This would lead to a night sky that is uniformly bright (as a star’s surface) ! This is not the case and so the assumption that the Universe is infinite must be flawed Radio sources ! Based on observations of radio sources of different strengths (so-called 2C and 3C surveys) ! The number of radio sources versus source strength concludes that the Universe has evolved from a denser place in the past ! This again appears to rule out the so-called Steady State Universe and gives support for the Big Bang Theory Cosmic Microwave Background ! CMBR was predicted as early as 1949 by Alpher and Herman (Gamow group) as a “remnant
    [Show full text]
  • Report from the Dark Energy Task Force (DETF)
    Fermi National Accelerator Laboratory Fermilab Particle Astrophysics Center P.O.Box 500 - MS209 Batavia, Il l i noi s • 60510 June 6, 2006 Dr. Garth Illingworth Chair, Astronomy and Astrophysics Advisory Committee Dr. Mel Shochet Chair, High Energy Physics Advisory Panel Dear Garth, Dear Mel, I am pleased to transmit to you the report of the Dark Energy Task Force. The report is a comprehensive study of the dark energy issue, perhaps the most compelling of all outstanding problems in physical science. In the Report, we outline the crucial need for a vigorous program to explore dark energy as fully as possible since it challenges our understanding of fundamental physical laws and the nature of the cosmos. We recommend that program elements include 1. Prompt critical evaluation of the benefits, costs, and risks of proposed long-term projects. 2. Commitment to a program combining observational techniques from one or more of these projects that will lead to a dramatic improvement in our understanding of dark energy. (A quantitative measure for that improvement is presented in the report.) 3. Immediately expanded support for long-term projects judged to be the most promising components of the long-term program. 4. Expanded support for ancillary measurements required for the long-term program and for projects that will improve our understanding and reduction of the dominant systematic measurement errors. 5. An immediate start for nearer term projects designed to advance our knowledge of dark energy and to develop the observational and analytical techniques that will be needed for the long-term program. Sincerely yours, on behalf of the Dark Energy Task Force, Edward Kolb Director, Particle Astrophysics Center Fermi National Accelerator Laboratory Professor of Astronomy and Astrophysics The University of Chicago REPORT OF THE DARK ENERGY TASK FORCE Dark energy appears to be the dominant component of the physical Universe, yet there is no persuasive theoretical explanation for its existence or magnitude.
    [Show full text]
  • Fine-Tuning, Complexity, and Life in the Multiverse*
    Fine-Tuning, Complexity, and Life in the Multiverse* Mario Livio Dept. of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA E-mail: [email protected] and Martin J. Rees Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA, UK E-mail: [email protected] Abstract The physical processes that determine the properties of our everyday world, and of the wider cosmos, are determined by some key numbers: the ‘constants’ of micro-physics and the parameters that describe the expanding universe in which we have emerged. We identify various steps in the emergence of stars, planets and life that are dependent on these fundamental numbers, and explore how these steps might have been changed — or completely prevented — if the numbers were different. We then outline some cosmological models where physical reality is vastly more extensive than the ‘universe’ that astronomers observe (perhaps even involving many ‘big bangs’) — which could perhaps encompass domains governed by different physics. Although the concept of a multiverse is still speculative, we argue that attempts to determine whether it exists constitute a genuinely scientific endeavor. If we indeed inhabit a multiverse, then we may have to accept that there can be no explanation other than anthropic reasoning for some features our world. _______________________ *Chapter for the book Consolidation of Fine Tuning 1 Introduction At their fundamental level, phenomena in our universe can be described by certain laws—the so-called “laws of nature” — and by the values of some three dozen parameters (e.g., [1]). Those parameters specify such physical quantities as the coupling constants of the weak and strong interactions in the Standard Model of particle physics, and the dark energy density, the baryon mass per photon, and the spatial curvature in cosmology.
    [Show full text]
  • Time-Dependent Cosmological Interpretation of Quantum Mechanics Emmanuel Moulay
    Time-dependent cosmological interpretation of quantum mechanics Emmanuel Moulay To cite this version: Emmanuel Moulay. Time-dependent cosmological interpretation of quantum mechanics. 2016. hal- 01169099v2 HAL Id: hal-01169099 https://hal.archives-ouvertes.fr/hal-01169099v2 Preprint submitted on 18 Nov 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Time-dependent cosmological interpretation of quantum mechanics Emmanuel Moulay∗ Abstract The aim of this article is to define a time-dependent cosmological inter- pretation of quantum mechanics in the context of an infinite open FLRW universe. A time-dependent quantum state is defined for observers in sim- ilar observable universes by using the particle horizon. Then, we prove that the wave function collapse of this quantum state is avoided. 1 Introduction A new interpretation of quantum mechanics, called the cosmological interpre- tation of quantum mechanics, has been developed in order to take into account the new paradigm of eternal inflation [1, 2, 3]. Eternal inflation can lead to a collection of infinite open Friedmann-Lemaˆıtre-Robertson-Walker (FLRW) bub- ble universes belonging to a multiverse [4, 5, 6]. This inflationary scenario is called open inflation [7, 8].
    [Show full text]
  • Primordial Gravitational Waves and Cosmology Arxiv:1004.2504V1
    Primordial Gravitational Waves and Cosmology Lawrence Krauss,1∗ Scott Dodelson,2;3;4 Stephan Meyer 3;4;5;6 1School of Earth and Space Exploration and Department of Physics, Arizona State University, PO Box 871404, Tempe, AZ 85287 2Center for Particle Astrophysics, Fermi National Laboratory PO Box 500, Batavia, IL 60510 3Department of Astronomy and Astrophysics 4Kavli Institute of Cosmological Physics 5Department of Physics 6Enrico Fermi Institute University of Chicago, 5640 S. Ellis Ave, Chicago, IL 60637 ∗To whom correspondence should be addressed; E-mail: [email protected]. The observation of primordial gravitational waves could provide a new and unique window on the earliest moments in the history of the universe, and on possible new physics at energies many orders of magnitude beyond those acces- sible at particle accelerators. Such waves might be detectable soon in current or planned satellite experiments that will probe for characteristic imprints in arXiv:1004.2504v1 [astro-ph.CO] 14 Apr 2010 the polarization of the cosmic microwave background (CMB), or later with di- rect space-based interferometers. A positive detection could provide definitive evidence for Inflation in the early universe, and would constrain new physics from the Grand Unification scale to the Planck scale. 1 Introduction Observations made over the past decade have led to a standard model of cosmology: a flat universe dominated by unknown forms of dark energy and dark matter. However, while all available cosmological data are consistent with this model, the origin of neither the dark energy nor the dark matter is known. The resolution of these mysteries may require us to probe back to the earliest moments of the big bang expansion, but before a period of about 380,000 years, the universe was both hot and opaque to electromagnetic radiation.
    [Show full text]
  • 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).
    [Show full text]
  • Quantifying the Sensitivity of Big Bang Nucleosynthesis to Isospin Breaking
    W&M ScholarWorks Undergraduate Honors Theses Theses, Dissertations, & Master Projects 5-2016 Quantifying the Sensitivity of Big Bang Nucleosynthesis to Isospin Breaking Matthew Ramin Hamedani Heffernan College of William and Mary Follow this and additional works at: https://scholarworks.wm.edu/honorstheses Part of the Nuclear Commons Recommended Citation Heffernan, Matthew Ramin Hamedani, "Quantifying the Sensitivity of Big Bang Nucleosynthesis to Isospin Breaking" (2016). Undergraduate Honors Theses. Paper 974. https://scholarworks.wm.edu/honorstheses/974 This Honors Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Undergraduate Honors Theses by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Quantifying the Sensitivity of Big Bang Nucleosynthesis to Isospin Breaking Matthew Heffernan Advisor: Andr´eWalker-Loud Abstract We perform a quantitative study of the sensitivity of Big Bang Nucleosynthesis (BBN) to the two sources of isospin breaking in the Standard Model (SM), the split- 1 ting between the down and up quark masses, δq (md mu) and the electromagnetic ≡ 2 − coupling constant, αf:s:. To very good approximation, the neutron-proton mass split- ting, ∆m mn mp, depends linearly upon these two quantities. In turn, BBN is very ≡ − sensitive to ∆m. A simultaneous study of both of these sources of isospin violation had not yet been performed. Quantifying the simultaneous sensitivity of BBN to δq and αf:s: is interesting as ∆m increases with increasing δq but decreases with increasing αf:s:. A combined analysis may reveal weaker constraints upon possible variations of these fundamental constants of the SM.
    [Show full text]
  • Arxiv:1707.01004V1 [Astro-Ph.CO] 4 Jul 2017
    July 5, 2017 0:15 WSPC/INSTRUCTION FILE coc2ijmpe International Journal of Modern Physics E c World Scientific Publishing Company Primordial Nucleosynthesis Alain Coc Centre de Sciences Nucl´eaires et de Sciences de la Mati`ere (CSNSM), CNRS/IN2P3, Univ. Paris-Sud, Universit´eParis–Saclay, Bˆatiment 104, F–91405 Orsay Campus, France [email protected] Elisabeth Vangioni Institut d’Astrophysique de Paris, UMR-7095 du CNRS, Universit´ePierre et Marie Curie, 98 bis bd Arago, 75014 Paris (France), Sorbonne Universit´es, Institut Lagrange de Paris, 98 bis bd Arago, 75014 Paris (France) [email protected] Received July 5, 2017 Revised Day Month Year Primordial nucleosynthesis, or big bang nucleosynthesis (BBN), is one of the three evi- dences for the big bang model, together with the expansion of the universe and the Cos- mic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of 4He, D, 3He and 7Li deduced from observations, and calculated in primordial nucleosynthesis. However, there remains a yet–unexplained discrepancy of a factor ≈3, between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations. The precision in deuterium observations in cosmological clouds has recently improved dramatically, so that nuclear cross sections involved in deuterium BBN need to be known with similar precision. We will shortly discuss nuclear aspects re- lated to BBN of Li and D, BBN with non-standard neutron sources, and finally, improved sensitivity studies using Monte Carlo that can be used in other sites of nucleosynthesis.
    [Show full text]
  • The Reionization of Cosmic Hydrogen by the First Galaxies Abstract 1
    David Goodstein’s Cosmology Book The Reionization of Cosmic Hydrogen by the First Galaxies Abraham Loeb Department of Astronomy, Harvard University, 60 Garden St., Cambridge MA, 02138 Abstract Cosmology is by now a mature experimental science. We are privileged to live at a time when the story of genesis (how the Universe started and developed) can be critically explored by direct observations. Looking deep into the Universe through powerful telescopes, we can see images of the Universe when it was younger because of the finite time it takes light to travel to us from distant sources. Existing data sets include an image of the Universe when it was 0.4 million years old (in the form of the cosmic microwave background), as well as images of individual galaxies when the Universe was older than a billion years. But there is a serious challenge: in between these two epochs was a period when the Universe was dark, stars had not yet formed, and the cosmic microwave background no longer traced the distribution of matter. And this is precisely the most interesting period, when the primordial soup evolved into the rich zoo of objects we now see. The observers are moving ahead along several fronts. The first involves the construction of large infrared telescopes on the ground and in space, that will provide us with new photos of the first galaxies. Current plans include ground-based telescopes which are 24-42 meter in diameter, and NASA’s successor to the Hubble Space Telescope, called the James Webb Space Telescope. In addition, several observational groups around the globe are constructing radio arrays that will be capable of mapping the three-dimensional distribution of cosmic hydrogen in the infant Universe.
    [Show full text]
  • Inflationary Cosmology: from Theory to Observations
    Inflationary Cosmology: From Theory to Observations J. Alberto V´azquez1, 2, Luis, E. Padilla2, and Tonatiuh Matos2 1Instituto de Ciencias F´ısicas,Universidad Nacional Aut´onomade Mexico, Apdo. Postal 48-3, 62251 Cuernavaca, Morelos, M´exico. 2Departamento de F´ısica,Centro de Investigaci´ony de Estudios Avanzados del IPN, M´exico. February 10, 2020 Abstract The main aim of this paper is to provide a qualitative introduction to the cosmological inflation theory and its relationship with current cosmological observations. The inflationary model solves many of the fundamental problems that challenge the Standard Big Bang cosmology, such as the Flatness, Horizon, and the magnetic Monopole problems. Additionally, it provides an explanation for the initial conditions observed throughout the Large-Scale Structure of the Universe, such as galaxies. In this review, we describe general solutions to the problems in the Big Bang cosmology carry out by a single scalar field. Then, with the use of current surveys, we show the constraints imposed on the inflationary parameters (ns; r), which allow us to make the connection between theoretical and observational cosmology. In this way, with the latest results, it is possible to select, or at least to constrain, the right inflationary model, parameterized by a single scalar field potential V (φ). Abstract El objetivo principal de este art´ıculoes ofrecer una introducci´oncualitativa a la teor´ıade la inflaci´onc´osmica y su relaci´oncon observaciones actuales. El modelo inflacionario resuelve algunos problemas fundamentales que desaf´ıanal modelo est´andarcosmol´ogico,denominado modelo del Big Bang caliente, como el problema de la Planicidad, el Horizonte y la inexistencia de Monopolos magn´eticos.Adicionalmente, provee una explicaci´onal origen de la estructura a gran escala del Universo, como son las galaxias.
    [Show full text]
  • DARK AGES of the Universe the DARK AGES of the Universe Astronomers Are Trying to fill in the Blank Pages in Our Photo Album of the Infant Universe by Abraham Loeb
    THE DARK AGES of the Universe THE DARK AGES of the Universe Astronomers are trying to fill in the blank pages in our photo album of the infant universe By Abraham Loeb W hen I look up into the sky at night, I often wonder whether we humans are too preoccupied with ourselves. There is much more to the universe than meets the eye on earth. As an astrophysicist I have the privilege of being paid to think about it, and it puts things in perspective for me. There are things that I would otherwise be bothered by—my own death, for example. Everyone will die sometime, but when I see the universe as a whole, it gives me a sense of longevity. I do not care so much about myself as I would otherwise, because of the big picture. Cosmologists are addressing some of the fundamental questions that people attempted to resolve over the centuries through philosophical thinking, but we are doing so based on systematic observation and a quantitative methodology. Perhaps the greatest triumph of the past century has been a model of the uni- verse that is supported by a large body of data. The value of such a model to our society is sometimes underappreciated. When I open the daily newspaper as part of my morning routine, I often see lengthy de- scriptions of conflicts between people about borders, possessions or liberties. Today’s news is often forgotten a few days later. But when one opens ancient texts that have appealed to a broad audience over a longer period of time, such as the Bible, what does one often find in the opening chap- ter? A discussion of how the constituents of the universe—light, stars, life—were created.
    [Show full text]
  • Phy306 Introduction to Cosmology Homework 3 Notes
    PHY306 INTRODUCTION TO COSMOLOGY HOMEWORK 3 NOTES 1. Show that, for a universe which is not flat, 1 − Ω 1 − Ω = , where Ω = Ω r + Ω m + Ω Λ and the subscript 0 refers to the present time. [2] This was generally quite well done, although rather lacking in explanation. You should really define the Ωs, and you need to explain that you divide the expression for t by that for t0. 2. Suppose that inflation takes place around 10 −35 s after the Big Bang. Assume the following simplified properties of the universe: ● it is matter dominated from the end of inflation to the present day; ● at the present day 0.9 ≤ Ω ≤ 1.1; ● the universe is currently 10 10 years old; ● inflation is driven by a cosmological constant. Using these assumptions, calculate the minimum amount of inflation needed to resolve the flatness problem, and hence determine the value of the cosmological constant required if the inflation period ends at t = 10 −34 s. [4] This was not well done at all, although it is not really a complicated calculation. I think the principal problem was that people simply did not think it through—not only do you not explain what you’re doing to the marker, you frequently don’t explain it to yourself! Some people therefore got hopelessly confused between the two time periods involved—the matter-dominated epoch from 10 −34 s to 10 10 years, and the inflationary period from 10 −35 to 10 −34 s. The most common error—in fact, considerably more common than the right answer—was simply assuming that during the post-inflationary epoch 1 − .
    [Show full text]