1 / 16

Inflation, Dark Energy, and the Cosmological Constant

Inflation, Dark Energy, and the Cosmological Constant. Intro Cosmology Short Course Lecture 5 Paul Stankus, ORNL. L= 0. Recall from Lecture 4:. The Friedmann Equation. GR. yadda, yadda, yadda…. Basic Thermodynamics. Hot. Sudden expansion, fluid fills empty space without loss of energy.

keita
Download Presentation

Inflation, Dark Energy, and the Cosmological Constant

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Inflation, Dark Energy, and the Cosmological Constant Intro Cosmology Short Course Lecture 5 Paul Stankus, ORNL

  2. L=0 Recall from Lecture 4: The Friedmann Equation GR yadda, yadda, yadda…

  3. Basic Thermodynamics Hot Sudden expansion, fluid fills empty space without loss of energy. dE = 0 PdV > 0 thereforedS > 0 Hot Hot Gradual expansion (equilibrium maintained), fluid loses energy through PdV work. dE = -PdVif and only ifdS = 0 Hot Isentropic Adiabatic Perfect Fluid Cool

  4. L=0 No static Universes! Big Bang! The Friedmann Equation Together with the perfect fluid assumption dE=-PdVgives The second/dynamical Friedmann Equation

  5. L=0 Over- Column A Column B B. RiemannGerman G. Ricci-Curbastro Italian Formalized non-Euclidean geometry (1854) Tensor calculus (1888)

  6. Einstein closed, static Universe “The Heavens endure from everlasting to everlasting.” The full Friedmann equations with non-zero “cosmological constant” L Albert Einstein German General Theory of Relativity (1915); Static, closed universe (1917)

  7. Indistinguishable! Cosmological constant as part of General Relativity Space filled by energy of uniform density and P=-r Cosmological “Leftists” vs “Rightists” Left:L as part of geometry Right:L as part of energy&pressure Tmnfor matter and radiation in local rest frame Effective Tmnin the presence of a cosmological constant

  8. Continuum Inflationary Universes What if a flat Universe had no matter or radiation but onlycosmological constant (and/or vacuum energy)? “de Sitter Space” Exponentially expanding! …but yet oddly static:No beginning, no ending, H(t) never changes W. de Sitter Dutch Vacuum-energy-filled universes “de Sitter space” (1917)

  9. Unchanged! E E Negative pressure: not so exotic…. Constant energy density  Negative pressure

  10. Radiation Dominated Inflationary De Sitter Light Cones in De Sitter Space Robertson-Walker Coordinates t (1/H0) Radiation-filled Us Now BB Vacuum-energy-filled c(c/H0)

  11. Radiation Dominated Inflationary De Sitter Inflation solves (I): Uniformity/Entropy Robertson-Walker Coordinates t (1/H0) Alan Guth American Us Now Cosmological inflation (1981) CMB decouples  Inflation BB no inflation  BB with inflation  c(c/H0)

  12. L=0 Inflation Solves (II): Early Flatness (Yet another) Friedmann Equation Non-Flatness grows ~a(t)  Huge increase!? Dominates with increasing a(t), leading to faster increase

  13. L0 Flat (Generic) Open Closed

  14. Horizon Our lonely future? Matter/radiation Dark energy

  15. The New Standard Cosmology in Four Easy Steps Inflation, dominated by “inflaton field” vacuum energy Radiation-dominated thermal equilibrium Matter-dominated, non-uniformities grow (structure) Start of acceleration in a(t), return to domination by cosmological constant and/or vacuum energy. w=P/r +1/3 accdec t -1/3 -1 aeHt at1/2 at2/3 now

  16. Points to take home • For full behavior of a(t), need an equation of state (P/r) • Matter/radiation universes: evolving, and finite age • Cosmological constant L a legal but unneeded piece of GR; L is indistinguishable from constant-density vacuum energy • All L>0 evolve to inflationary (de Sitter) universes; Do we live at a special time? Part 2 • Early inflation solves flatness and uniformity puzzles • Life in inflationary spaces is very lonely

More Related