Where is the Universe?

Cosmological Cosmological QuestionsQuestions TemporalTemporal SpatialSpatial CompositionalCompositional TeleologicalTeleological

Behind physics is the more ancient and honorable traditionBehind physics is the more ancient and honorable traditionof attempts to understand where the world came from, whereof attempts to understand where the world came from, whereit is going, and why.it is going, and why.

P. J. E. PeeblesP. J. E. Peebles

Early ConceptionsEarly Conceptions BabylonianBabylonian EgyptianEgyptian HebraicHebraic Pre-SocraticPre-Socratic AristotelianAristotelian

Geocentric/AristotelianGeocentric/Aristotelian

Principle of Principle of PlenitudePlenitude

QuintessenceQuintessence

MedievalMedieval Dante’sDante’s

‘Moral’‘Moral’CosmologCosmologyy

GeocentriGeocentricc

TheologyTheology basedbased

Copernican CosmosCopernican Cosmos

Matter & SpaceMatter & Space

So, the Universe is……So, the Universe is……

Created?Created?

Changing?Changing?

M a y b M a y b ee . . . . . . . . . .

DEFINITELY DEFINITELY NOT!NOT!

Geometry 0Geometry 0

Uniform: homogeneous & isotropicUniform: homogeneous & isotropic Congruence geometryCongruence geometry

Euclidean (Euclid)Euclidean (Euclid) Spherical (Riemann)Spherical (Riemann) Hyperbolic (Gauss, Lobachevski, Bolyai)Hyperbolic (Gauss, Lobachevski, Bolyai)

Geometry 1Geometry 1 EuclideanEuclidean

1 parallel1 parallel

Triangle: 180Triangle: 180oo

C = C = ππ D D

Geometry 2Geometry 2 SphericalSpherical

0 parallels0 parallels

Triangle: >180Triangle: >180oo

C < C < ππ D D

Geometry 3Geometry 3 HyperbolicHyperbolic

∞ ∞ parallelsparallels

Triangle: <180Triangle: <180oo

C > C > ππ D D

Geometry Affects AppearanceGeometry Affects Appearance EuclideanEuclidean

SphericalSpherical

HyperbolicHyperbolic

EinsteinEinstein Special RelativitySpecial Relativity

Space-TimeSpace-Time General RelativityGeneral Relativity

Mass curves Mass curves SpacetimeSpacetime

Solutions of Einstein’s Solutions of Einstein’s Field EquationsField Equations Evolving universeEvolving universe

Cosmological Cosmological constantconstant

Evolving UniversesEvolving Universes

How much can we see?How much can we see?

Hubble’s LawHubble’s Law

V = HV = H0 0 DD

Everything recedes from everything!Everything recedes from everything!

Abundance of Light IsotopesAbundance of Light Isotopes

CCosmic osmic MMicrowaveicrowaveBBackground ackground RRadiationadiation

Tiny (significant) FluctuationsTiny (significant) Fluctuations

Hot Big Bang ModelHot Big Bang Model

ProblemsProblems Horizon Horizon

problemproblem

Flatness Flatness problemproblem

‘‘Goldilocks’ Goldilocks’ problemproblem

More?More?

InflationInflation

Ω = 1Ω = 1

Dark Matter: The EvidenceDark Matter: The Evidence ‘‘Peculiar’ motion of Peculiar’ motion of

stars (Oort)stars (Oort) Coma cluster Coma cluster

(Zwicky)(Zwicky)ClusterSimClusterSim

Galaxy rotationGalaxy rotation GalRotGalRot

Galaxy clustersGalaxy clusters SuperclustersSuperclusters

NGC3198

Dark Matter: What is it?Dark Matter: What is it?

Dark Matter Not Dark Matter

BaryonicBaryonic MACHOsMACHOs

PlanetsPlanetsBrown dwarfsBrown dwarfsRed dwarfsRed dwarfsBlack holesBlack holes

Hot gasHot gas

Non-BaryonicNon-Baryonic HDMHDM

NeutrinosNeutrinos CDMCDM

WIMPsWIMPsAxionsAxionsPhotinosPhotinosQuark nuggetsQuark nuggets

WhatWhat’s the Matter?’s the Matter?

Accidents HappenAccidents Happen

Find the SupernovaFind the Supernova

How It’s DoneHow It’s Done

SupernovaeSupernovae

SNAPSNAP

CMBCMB Penzias/WilsonPenzias/Wilson

COBECOBE

BoomerangBoomerang

WMAPWMAP

Dark EnergyDark Energy Cosmological Cosmological

constant (constant (ΛΛ) or ) or vacuum energyvacuum energy constantconstant

QuintessenceQuintessence DynamicDynamic EvolvingEvolving Spatially Spatially

dependentdependent

k-essencek-essence ““tracker” fieldstracker” fields predicted by predicted by

some particle some particle physics theoriesphysics theories

WhatWhat’s the Universe?’s the Universe?

Putting It All TogetherPutting It All Together

Recipe for Our UniverseRecipe for Our Universe

History of UniverseHistory of Universe

Cubs return to Cubs return to World SeriesWorld Series

Whither the Universe?Whither the Universe?2 BY2 BY6 BY6 BY14 14 BYBY24 24 BYBY33 33 BYBY44 44 BYBY65 65 BYBY75 75 BYBY