Reminders

1 Online Quiz Chapter 16 Due Wednesday at11:59PM

2 Online Quiz Chapter 7 Due Saturday at11:59PM

3 Read Chaps: 16, 7, 8, 184 Final Exam Wed Dec 16, 8:00am

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Lecture 36 — Cosmology Part II

2

Read Chapter 16

3

Cosmological Principle

Universe is homogeneousUniverse is isotropicCMBR: Penzias and Wilson, remnant fromthe Big BangObservational confirmation of CosmologicalPrinciple

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The Big Bang

5

CMBR: Evidence for the Big Bang

6

Olber’s Paradox

Why is the night sky dark?The need for a beginning

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In a forest every line of sight ends ona tree

8

Every line of Sight Should end on astar

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The Nature of the Universe

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Redshift is NOT due to DopplerEffectRedshift is due to expansion of the universe

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The Universe is Curved

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The Fate of the Universe depends ongeometry

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CMBR: Evidence for the Big Bang

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History of the Universe

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Decoupling of CBR

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Big Bang Nucleosynthesis

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Big Bang NucleosynthesisDetermines Density of OrdinaryMatter

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Fate of the Universe Depends onDensity

Hubble’s Lawv = H0d

Critical Density: Density Just Needed toClose the Universe ρcr

Omega’s: Ratio of Density to Critical Density

ΩB =ρb

ρcr

ΩM =ρM

ρcr19

SNe Ia: Discovery of Dark Energy

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Supernova Cosmology Project: SNdiscovery

SupernovaDiscovery

(as seen from Hubble SpaceTelescope)

Difference

(as seen fromtelescopes on Earth)

3 Weeks Before

Supernova 1998baSupernova Cosmology Project

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SNe Ia are Correctable Candles

-20 0 20 40 60

-15

-16

-17

-18

-19

-20

-20 0 20 40 60

-15

-16

-17

-18

-19

-20

B Band

as measured

light-curve timescale“stretch-factor” corrected

days

MB

– 5

log(

h/6

5)

days

MB

– 5

log(

h/6

5)

Calan/Tololo SNe Ia

Kim, et al. (1997)

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Evolution of the Universe

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COBE: The Universe is Flat

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WMAP: The Universe is Flat

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Age and Fate of the Universe

Geometry and Fate of the Universe

Ω and Λ

Inflation: Horizon and Flatness ProblemsDark Matter: Neutrinos, MACHOS, WIMPsDark Energy

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CMBR: Same TemperatureEverywhere Horizon Problem

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Solution: Inflation

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Fate of Universe Depends on DarkEnergy

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Cosmology Summary

Universe is Flat: CBRΩM + ΩΛ = 1ΩM ∼ 0.3 : Rich ClustersΩΛ ∼ 0.7 : Type Ia SupernovaeΩb ∼ 0.03: Big Bang Nucleosynthesis

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Inclass #6

Define each of the following, explain why we thinkeach exists, and why each is weird:1 Dark Matter2 Dark Energy3 InflationWhich of these is weirder in your opinion?

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