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Cosmology Christian Stegmann University of Erlangen-Nuremberg. Big Bang. today. The Earth …. Heute. … one of eight planets. today. Stars. today. The Milky Way. today. ... full of stars. today. and nebulae. today. Our Milky Way. today. The Universe is full of galaxies. today.
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CosmologyChristian StegmannUniversity of Erlangen-Nuremberg Big Bang today
The Earth … Heute
… one of eight planets today
Stars today
The Milky Way ... today
... full of stars today
and nebulae today
Our Milky Way today
Galaxy cluster today
Edwin Hubbles Discovery today • Galaxies travel away from us • the further away, the faster
Galaxies are moving today
Do we understand that? today • We are the centre of the Universe! • The Universe is expanding • Space between galaxies is getting larger Scientifically more attractive!
today some time later
How do we measure this? today • Measurement of the velocity • velocity-meter? • Distance • Ruler?
Cosmological red shift today Space is expanding
Galaxy-spektroscopy today Star-spektrum Sodium Magnesium Galaxy-spektrum Calcium vGalaxy~ 12000 km/s
Distance measurement today R apparent brightness ~ true brightness . 1/R2
today measured brightness measured brightness known distance measured distance brightness One point and all is determined distance, R
We need lamps! today
Star explosions today • 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
Where is the supernova? today
Here! today
„Standard candles“ today
The Hubble-Diagram Heute Distance red shift (velocity)
today • The Universe is expanding (acclerating)! • The Universe was smaller at earlier times • The Universe was created in a hot phase The Big Bang
World models today
General relativity today • 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
Space curvature today
Solution Heute Homogeneous but not isotrop Isotrop but not homogeneous • Cosmological principle • We see what every other sees • Isotrop and homogeneous Universe • Friedmann Universe (1922) • World models depend only on • Expansion • Gravitational attraction Isotrop AND homogeneous
Distribution of galaxies today
The accelerated Universe • Einsteins cosmological constant • cosmological constant acts like an anti-gravitation
A time travel 10-42 s • Age = 10-42 s • The beginning of physics • Age = 10-36 s, T = 1027 K • Strong and electroweak force decouple
The inflation 10-36s • Age = 10-36 s, T = 1021 K • Sudden expansion of the Universe by a factor 1020 – 1030 • The Universe gets flat!
The battle 10-6 s • Age = 10-6 s, T = 1012 Kelvin • Matter and antimatter annihilate • Matter-antimatter-ratio 100000001 : 10000000 • Matter-photon-ratio 1 : 100000000
Nukleosynthesis 1 min • Age = 1 min, T = 109 K • Generation of light elements • Hydrogen, Deuterium, Helium, Lithium
Nuclear fusion 1 min • Fusion in collisions • Fusion requries high temperatures and large densities Strong electo-static repulsion at intermediate distances Forvce particle distance Strong nuclear attraction at smal distances
Primordiale Nukleosynthesis 1 min • 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
Generation of atoms 370000 years • Age = 370000 Jahre, T = 3000 Kelvin • First atoms generated • The Universe becomes transparent
Can we see the Big Bang? 370000 years
Back into the past 370000 years 4 light years
370000 years 2 million light years
Back into the past some billions of light years Each view into the Universe is a view back into the past
The Big Bang fills the sky 370000 Jahre
The Big Bang past - now 370000 years Past: Light 3000 K today: Mikrowaves 3 K