cosmology christian stegmann university of erlangen-nuremberg

Christian Stegmann, Cosmology, CERN 2008

Time

CosmologyCosmology Christian StegmannUniversity of Erlangen-Nuremberg

Big Bang today


Time

The Earth …The Earth …Heute


Time

… … one of eight planetsone of eight planetstoday


Time

StarsStarstoday


Time

The Milky Way ...The Milky Way ...today


Time

... full of stars... full of starstoday


Time

and nebulaeand nebulaetoday


Time

Our Milky WayOur Milky Waytoday


Time

The Universe is full of galaxiesThe Universe is full of galaxiestoday


Time

Galaxy clusterGalaxy clustertoday


Time

Edwin Hubbles DiscoveryEdwin Hubbles Discovery

• Galaxies travel away from us

• the further away, the faster

today


Time

Galaxies are moving Galaxies are moving today


Time

Do we understand that?Do we understand that?

• We are the centre of the Universe!

• The Universe is expanding– Space between galaxies is getting larger

Scientifically more attractive!

today


Time

today


Time

some time later

today


Time

How do we measure this?How do we measure this?

• Measurement of the velocity– velocity-meter?

• Distance

– Ruler?

today


Time

Measurement of the velocity via the Measurement of the velocity via the red-shiftred-shift

today


Time

Cosmological red shiftCosmological red shift

Space is expanding

today


Time

Galaxy-spektroscopyGalaxy-spektroscopy

Calcium

Magnesium

Sodium

Galaxy-spektrum

Star-spektrum

vGalaxy ~ 12000 km/s

today


Time

Distance measurementDistance measurement

apparent brightness ~ true brightness . 1/R2

R

today


Time

distance, R

brightness

known distance

measuredbrightness

One point andall is determined

measuredbrightness

measureddistance

today


Time

We need lamps!We need lamps!

today


Time

Star explosionsStar explosions

• Supernova Typ Ia• Exploding white dwarfs

– nuclear bomb of the size of the Earth!

• Bright as a whole galaxy

• Light up and disappear after a few weeks

Supernova 1994D

today


Time

Where is the supernova?Where is the supernova?today


Time

Here!Here!today


Time

„„Standard candles“Standard candles“today


Time

The Hubble-DiagramThe Hubble-Diagram

red shift (velocity)

Dis

tan

ce

Heute


Time

• The Universe is expanding (acclerating)!

• The Universe was smaller at earlier times

• The Universe was created in a hot phase

The Big Bang

today


Time

World modelsWorld models

today


Time

General relativityGeneral relativity

• Einstein 1916• Describes all gravitationally bound

systems– planets– black holes – the Universe

• Mass produces curvature of the space• Curvature tells masses how to move

→ gravitation

today


Time

Space curvatureSpace curvaturetoday


Time

SolutionSolution

• Cosmological principle– We see what every other sees – Isotrop and homogeneous

Universe

• Friedmann Universe (1922)

• World models depend only on – Expansion – Gravitational attraction

Homogeneous but not isotrop

Isotrop but not homogeneous

Isotrop AND homogeneous

Heute


Time

Distribution of galaxiesDistribution of galaxiestoday


Time

The accelerated UniverseThe accelerated Universe

• Einsteins cosmological constant

• cosmological constant acts like an anti-

gravitation


Time

A travel through the timeA travel through the time


Time

First there was …First there was …0


Time

From Big Bang until todayFrom Big Bang until today0


Time

A time travelA time travel

• Age = 10-42 s– The beginning of physics

• Age = 10-36 s, T = 1027 K– Strong and electroweak force decouple

10-42 s


Time

The inflationThe inflation

• Age = 10-36 s, T = 1021 K – Sudden expansion of the Universe by a factor 1020 – 1030

– The Universe gets flat!

10-36s


Time

The battleThe battle

• Age = 10-6 s, T = 1012 Kelvin– Matter and antimatter annihilate

– Matter-antimatter-ratio

100000001 : 10000000

– Matter-photon-ratio

1 : 100000000

10-6 s


Time

NukleosynthesisNukleosynthesis

• Age = 1 min, T = 109 K– Generation of light

elements

– Hydrogen, Deuterium, Helium, Lithium

1 min


Time

Nuclear fusionNuclear fusion

• Fusion in collisions

• Fusion requries high temperatures and large densities

particle distanceFo

rvc

e

Strong electo-static repulsion at intermediate distances

Strong nuclear attraction at smal distances

1 min


Time

Primordiale NukleosynthesisPrimordiale Nukleosynthesis

• Explains the abundances of light elements

– 74% Hydrogen

– 25% Helium

– 1% other

• Baryonic density

– 3,5∙10-31 g/cm3 or

– 0,2 Hydrogen atoms/m3

1 min


Time

Generation of atomsGeneration of atoms

• Age = 370000 Jahre, T = 3000 Kelvin– First atoms generated

– The Universe becomes transparent

370000 years


Time

Can we see the Big Bang?Can we see the Big Bang?

370000 years


Time

Back into the pastBack into the past

4 light years

370000 years


Time

2 million light years

370000 years


Time

some billions of light years

Each view into the Universe isa view back into the past

Back into the pastBack into the past


Time

370000 Jahre

The Big Bang fills the skyThe Big Bang fills the sky


Time

The Big Bang past - nowThe Big Bang past - now

Past:Light 3000 K

today:Mikrowaves 3 K

370000 years


Time

1965 – The discovery1965 – The discovery

Microwave radiation from the cosmos

370000 years


Time

COBE and WMAPCOBE and WMAP

• COBE

– COsmic Background Explorer

– 1989 – 1993

– Nobel price 2006 (G. Smoot, J.

Mather)

• WMAP

– Wilkinson Microwave Anisotropy

Probe

– Start 2001

370000 years


Time

The microwave backgroundThe microwave background

T = 2.7 K

370000 years


Time

T = 0,0035 K

The Earth is movingThe Earth is moving370000 years


Time

The spectrumThe spectrum370000 years


Time

The history of the cosmic The history of the cosmic background radiationbackground radiation

observer

Surface of last scattering

Edge of the visible Universe.black body radiation

The visible Universe

black body radiation

370000 years


Time

T = 0,000018 K

The echo of the big bangThe echo of the big bang370000 years


Time

Multipol expansionMultipol expansion370000 years


Time

The power spectrumThe power spectrum370000 years


Time

Cosmological ParameterCosmological Parameter

– Total energiy density 1.003 ± 0.015

– Matter density 0.24 ± 0.04

– Baryon density 0.042 ± 0.004

– Vakuum energy density 0.76 ± 0.05

– Neutrino density < 0.014

– Age of the Universe 13.7 ± 0.2 Gyr


Time

60%

40%

20%

0%

80%

100%

Matter

Neutrinos

Stars

Neue Formvon Energie

Neue Formvon Materie

370000 Jahre


Time

SummarySummary

• Our Universe was created in a Big Bang

– Galaxy move away from us

– Abundances of light elements

– Cosmic microwave background

• 97% of the energy density of the Universe is

unknown!

today


Time


Time

Doppler effectDoppler effect

low frequency

red shift

high frequency

blue shift

today


Time

Spektra for identificationSpektra for identificationtoday


Time

Parameter of an expanding UniverseParameter of an expanding Universe

• Expansion ↔ Gravitational acceleration

• Expansion– Hubble constant H0 is a measure for the strength of the

expansion: H0 = 20 km/s/MLj

• Gravitational acceleration– Normal matter slows down the expansion (mean density

ρ)

– critical density, requried to stop expansion:

ρkrit = 3 H02/8πG = 10-29 g/cm3

today


Time

Geometry of the UniverseGeometry of the Universe

• Balance between contraction and expansion expresse by Ω0 = ρ/ρkrit

– Ω0 > 1, ρ > ρkrit

Gravitation wins, Universe collapse– Ω0 = 1, ρ = ρkrit

Expansion eventually stopps– Ω0 < 1, ρ < ρkrit

Expansion wins, Universum is expanding forever

• Λ > 0, fate of the Universe not connected to the geometry

today


Time

Why not in stars?Why not in stars?

1 min


Time

Fusion in starsFusion in stars1 min


Time

•

• Erwarte ungefähr genauso viel Helium wie andere Elemente mit großer Masse– Verhältnis: 75% H, 13% He, 12% Rest

Fusion in starsFusion in stars

Zeit

Ker

n T

em

pe

ratu

r

107 K

108 K

109 K

Wasserstoff-Brennen

Helium-Brennen

carbon-burning

1.5x107 K

6x108 K

1x108 K

H Brenn-SchaleHe Brenn-Schale

C Brenn-SchaleO Brenn-SchaleSi Brenn-Schale

Fe Kern- keine Fusion

1 min


Time

Vergleich Stellarer und Vergleich Stellarer und Primordialer NukleosynthesePrimordialer Nukleosynthese

109 : 11:1Photon-Baryon-Verhältnis

10-5 g/cm3

(wie die Luft in diesem Raum)

100 g/cm3Dichte

FallendAnsteigendTemperatur-entwicklung

MinutenMilliarden von Jahren

Zeitskala

Primordiale Nukleosynthese

Stellare Nukleosynthese

1 min


Time

Kosmologische ParameterKosmologische Parameter370000 Jahre


Time

Dunkle MaterieDunkle Materie

• Rotationskurven von Galaxien

• Elliptische Galaxien

• Gravitationslinsen

• Mikrowellen-Hintergrund

Heute


Time

RotationskurvenRotationskurvenHeute


Time

Galaxien-Cluster 1E 0657-Galaxien-Cluster 1E 0657-5656

optisch


Time

Galaxien-Cluster 1E 0657-Galaxien-Cluster 1E 0657-5656

Röntgen


Time

GravitationslinsenGravitationslinsen


Time

Optisch + Röntgen + Dunkle Materie


Time

Was ist passiert?Was ist passiert?


Time

Galaxien Cluster CL0024 17Galaxien Cluster CL0024 17Heute

cosmology christian stegmann university of erlangen-nuremberg

Documents