Create Presentation
Download Presentation

Download Presentation

Cosmic Inflation Phy 262 2014 Andreas Albrecht

Download Presentation
## Cosmic Inflation Phy 262 2014 Andreas Albrecht

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Cosmic Inflation**Phy 262 2014 Andreas Albrecht A. Albrecht Phy 262 2014**Cosmic Inflation:**• Great phenomenology, but • Original goal of explaining why the cosmos is *likely* to take the form we observe has proven very difficult to realize. A. Albrecht Phy 262 2014**Cosmic Inflation:**• Great phenomenology, but • Original goal of explaining why the cosmos is *likely* to take the form we observe has proven very difficult to realize. This Talk A. Albrecht Phy 262 2014**Cosmic Inflation:**• Great phenomenology, but • Original goal of explaining why the cosmos is *likely* to take the form we observe has proven very difficult to realize. • OR: Just be happy we have equations to solve? A. Albrecht Phy 262 2014**OUTLINE**Big Bang & inflation basics Eternal inflation de Sitter Equilibrium cosmology Cosmic curvature from de Sitter Equilibrium cosmology A. Albrecht Phy 262 2014**OUTLINE**Big Bang & inflation basics Eternal inflation de Sitter Equilibrium cosmology Cosmic curvature from de Sitter Equilibrium cosmology A. Albrecht Phy 262 2014**Friedmann Eqn.**A. Albrecht Phy 262 2014**Friedmann Eqn.**A. Albrecht Phy 262 2014**Friedmann Eqn.**Hubble parameter (“constant”, because today it takes ~10Billion years to change appreciable) A. Albrecht Phy 262 2014**Friedmann Eqn.**Hubble parameter (“constant”, because today it takes ~10Billion years to change appreciable) “Scale factor” A. Albrecht Phy 262 2014**Friedmann Eqn.**Curvature “Scale factor” A. Albrecht Phy 262 2014**Friedmann Eqn.**Curvature Relativistic Matter “Scale factor” A. Albrecht Phy 262 2014**Friedmann Eqn.**Curvature Non-relativistic Matter Relativistic Matter “Scale factor” A. Albrecht Phy 262 2014**Friedmann Eqn.**Dark Energy Curvature Non-relativistic Matter Relativistic Matter “Scale factor” A. Albrecht Phy 262 2014**Evolution of Cosmic Matter**A. Albrecht Phy 262 2014**Evolution of Cosmic Matter**A. Albrecht Phy 262 2014**Evolution of Cosmic Matter**A. Albrecht Phy 262 2014**The curvature feature/“problem”**A. Albrecht Phy 262 2014**The curvature feature/“problem”**! A. Albrecht Phy 262 2014**The curvature feature/“problem”**! A. Albrecht Phy 262 2014**The curvature feature/“problem”**! A. Albrecht Phy 262 2014**The curvature feature/“problem”**A. Albrecht Phy 262 2014**The curvature feature/“problem”**! A. Albrecht Phy 262 2014**i**W a 1 In the SBB, flatness is an “unstable fixed point”: Dominates with time At or The “GUT scale” Require today to 55 decimal places to get A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**i**W a 1 In the SBB, flatness is an “unstable fixed point”: SBB = “Standard Big Bang” cosmology, or “cosmology without inflation”. Dominates with time At or The “GUT scale” Require today to 55 decimal places to get A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**i**Gravitational instability: The Jeans Length Average energy density Sound speed • Overdense regions of size • collapse under their own weight. • If the size is they just oscillate A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**i**SBB Homogeneity: On very large scales the Universe is highly homogeneous, despite the fact that gravity will clump matter on scales greater than RJeans At the GUT epoch the observed Universe consisted of 1079RJeanssized regions. The Universe was very smooth to start with. NB: Flatness & Homogeneity SBB Universe starts in highly unstable state. A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**i**SBB Monopoles • A GUT phase transition (or any other process) that injects stable non-relativistic matter into the universe at early times (deep in radiation era, ie Ti =1016 GeV) will *ruin* cosmology: Monopole dominated Universe A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**The monopole “problem”**A. Albrecht Phy 262 2014**The monopole “problem”**! A. Albrecht Phy 262 2014**i**Here & Now SBB Horizon t=0 1080 causally disconnected regions at the GUT epoch Horizon: The distance light has traveled since the big bang: A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**The flatness, homogeneity & horizon features become**“problems” if one feels one must explain initial conditions. Basically, the SBB says the universe must start in a highly balanced (or “fine tuned”) state, like a pencil on its point. Must/can one explain this? Inflation says “yes” A. Albrecht Phy 262 2014 I.0 What is Cosmic Inflation?**Friedmann Eqn.**Dark Energy Curvature Non-relativistic Matter Relativistic Matter A. Albrecht Phy 262 2014**Now add cosmic inflation**Friedmann Eqn. Dark Energy Inflaton Curvature Non-relativistic Matter Relativistic Matter A. Albrecht Phy 262 2014**Now add cosmic inflation**Friedmann Eqn. Dark Energy Inflaton Curvature Non-relativistic Matter Relativistic Matter A. Albrecht Phy 262 2014**Now add cosmic inflation**Friedmann Eqn. Dark Energy Inflaton Curvature Non-relativistic Matter Relativistic Matter A. Albrecht Phy 262 2014**The inflaton:**~Homogeneous scalar field obeying Cosmic damping Coupling to ordinary matter All potentials have a “low roll” (overdamped) regime where A. Albrecht Phy 262 2014**The inflaton:**~Homogeneous scalar field obeying Cosmic damping Coupling to ordinary matter All potentials have a “low roll” (overdamped) regime where A. Albrecht Phy 262 2014**Add a period of Inflation:**A. Albrecht Phy 262 2014**With inflation, initially large curvature is OK:**A. Albrecht Phy 262 2014**With inflation, early production of large amounts of**non-relativistic matter (monopoles) is ok : A. Albrecht Phy 262 2014**With inflation, early production of large amounts of**non-relativistic matter (monopoles) is ok : A. Albrecht Phy 262 2014**Inflation detail:**A. Albrecht Phy 262 2014**Inflation detail:**A. Albrecht Phy 262 2014**Hubble Length**A. Albrecht Phy 262 2014**Hubble Length**(aka ) A. Albrecht Phy 262 2014