Big Bang A Trip to the Beginning of the Universe by Stefan Diehl

Overview Introduction Introduction History of the Big-Bang-Theory History of the Big-Bang-Theory Trip to the Big-Bang Trip to the Big-Bang From the Plank - Epoch to the formation From the Plank - Epoch to the formation of galaxies of galaxies

Introduction Today: ~ 14 billion years after the Big Bang The Earth is home to many different animals and plants But the mankind is the only one who asks the question, where we came from and where we go to

How did the idea came up, that everything started with a Big Bang? 1929 Edwin Hubbel: The distance to far away galaxies is The distance to far away galaxies is genarally proportional to their redshifts genarally proportional to their redshifts  Very distant galaxies have an velocity directly away from our vantage point away from our vantage point  The farther away, the higher the velocity By the redshift of galxies we can meassure their velocity

If the distance between galaxy clusters is increasing today, everything must have been closer together in the past Big Bang

Another proof for the Big Bang … 1965: Arno Penzias and Robert Wilson discovered the cosmic background radiation Picture of the universe years after the Big-Bang, when recombination of photons and matter ended … The redshift of this radiation is a proof for the expansion of the universe

Let`s start our Trip today starting point point

The earliest phases of the universe are subject to much speculation Most common models: Incredibly high energy density Incredibly high energy density Huge temperatures and pressures Huge temperatures and pressures Time and space lost their status as a continuum (didn`t exist any more) Time and space lost their status as a continuum (didn`t exist any more) How everything started … Theory of quantum gravitation

The Plank – Epoch < s All fundamental forces were united in one elementary force interaction of Quarks Beta - radiation electro- magnetic force weaknuclearforce strong nuclear force gravi-tation

After this time: After this time: A very fast expansion started A very fast expansion started The gravitation splits of The gravitation splits of from the other forces from the other forces GUT – force (Grand Unified Theorie) GUT – force (Grand Unified Theorie) We don‘t know much about this time and the particles which existed in it

Inflation and Quark - Epoch A phase transition caused a cosmic inflation A phase transition caused a cosmic inflation Universe expanded exponentially Universe expanded exponentially Strong nuclear force split of from the GUT - force Strong nuclear force split of from the GUT - force When inflation stopped: When inflation stopped: The universe consisted of a quark-gluon plasma, The universe consisted of a quark-gluon plasma, as well as all other elementary particles as well as all other elementary particles Temperatures were so high (10 13 K) that the random motions of particles were at relativistic speeds Temperatures were so high (10 13 K) that the random motions of particles were at relativistic speeds Particle-antiparticle pairs of all kinds were being continuously Particle-antiparticle pairs of all kinds were being continuously created and destroyed in collisions created and destroyed in collisions

Quark - Epoch At some point: Beginning of the baryogenesis Leaded to a very small excess of quarks and Leaded to a very small excess of quarks and leptons over antiquarks and anti-leptons leptons over antiquarks and anti-leptons (about 1 part in 30 million) (about 1 part in 30 million) Result: Predominance of matter over antimatter Result: Predominance of matter over antimatter in the present universe in the present universe Thank to this asymmetry for our life

Four Fundamental Forces electroweak force weak nuclear force electromagnetic force split of All fundamental forces we know, existed in this moment

Formation of the Basic Particles of Matter One part in a billion of a second after the Big Bang: Quarks and gluons combined to form baryons (protons and neutrons) Quarks and gluons combined to form baryons (protons and neutrons) The temperature of K was no longer high enough The temperature of K was no longer high enough to create new proton-antiproton pairs to create new proton-antiproton pairs mass annihilation mass annihilation only a small part of the only a small part of the original protons and neutrons survived, original protons and neutrons survived, but none of their antiparticles but none of their antiparticles

Formation of the Basic Particles of Matter Around one second after the Big Bang a similar process happened for electrons and positrons Quarks and gluons didn`t exist Quarks and gluons didn`t exist as free particles any more as free particles any more At this point we have all the particles we need to construct elements Protons Protons Neutrons Neutrons Elektrons Elektrons Why don`t we start ?

Beginning of the Nucleosynthesis … A few minutes after the beginning of the expansion The temperature was about one billion Kelvin and the density was about that of air The temperature was about one billion Kelvin and the density was about that of air Beginning of the „Big Bang“ nucleosynthesis Neutrons combined with protons to form the universe's first deuterium and helium nuclei Neutrons combined with protons to form the universe's first deuterium and helium nuclei 75 % Protons 75 % Protons 25 % Helium-4 25 % Helium-4 0,001 % Deuterium 0,001 % Deuterium Lithium, Beryllium Lithium, Beryllium

The First Hydrogen Atoms After about 379,000 years … Temperature was fallen Temperature was fallen under 3000 K under 3000 K Electrons and nuclei combined Electrons and nuclei combined into atoms (mostly hydrogen) into atoms (mostly hydrogen) radiation decoupled from matter and continued radiation decoupled from matter and continued passing through space since today passing through space since today This relic radiation is known as the cosmic microwave background radiation today background radiation today By the expansion of the universe the By the expansion of the universe the wavelength of this radiation increased wavelength of this radiation increased redshift redshift

Let`s lock on our map: today starting point our actual position

How Galaxies were Built Over a long period of time … Denser regions of the nearly uniformly distributed matter gravitationally attracted other matter They grew even denser They grew even denser Gas clouds were formed Gas clouds were formed

How the First Stars begin to Burn If a part of such a cloud has reached a special density, the other parts collaps into it density, the other parts collaps into it Temperature increases up to 10 6 K Fusion of deuterium starts and produces more energy and produces more energy temperature increases temperature increases A star is born, in which A star is born, in which the fusion continues with the fusion continues with other elements other elements

Is there a limit for Nuclear Fusion? Nuclear fusion can only produce Nuclear fusion can only produce the elements up to iron the elements up to iron Fusion of heavy nucleons needs energy Fusion of heavy nucleons needs energy

Where did the other Elements come from? Supernova Explosion of a heavy star Explosion of a heavy star Very high energy and density Very high energy and density In this situation neutrons can be captured by havy nuclei and transformed into protons by emission of beta radiation by emission of beta radiation Heavy elements like uranium exist on earth All of us are a relict of a supernova All of us are a relict of a supernova many many years ago many many years ago

today starting point We have reached our goal …

But, how will the trip go on? Will there be a Big Crunch sometime? Will the expansion slow down, but go on forever? Many open questions … But one thing is sure: Mankind is only a very small point in the history of time and space

References Prof. Cassing Talk 2 „Physik im Blick 2007“ Prof. Cassing Talk 2 „Physik im Blick 2007“ (pictures) (pictures)