1. Marion Mikusch Physics institute, university of Graz

2.  molecules: do not have enough Ekin  triggers: compressions  Jeans mass and Jeans radius:

3.  contraction  Epot is released  if heat is transported off  collapse  free falling time:  protostar is born

4.  Different phases: ◦ hydrogen burning ◦ helium burning ◦ carbon, neon, oxygen, silicate burning  stage of equilibrium until fuel is depleted   a new thermonuclear process starts  Stars over 8 sm: also heavy elements are built  iron-nickel core is formed  supernova

5.  neutron star: e+p  n  until internal pressure prevents contraction  Star over 30 sm: unstoppable collapse  a black hole is born

6.  escape velocity reaches the speed of light  Schwarzschild radius:  causal border  black hole with 10 sm: R s = 29,5 km  event horizon: surface around the black hole

7.  interstellar matter approches in spiral tracks  X-ray emission  rotation  space-time geometry is distorted  ‘electromagnetic tornado‘

8.  analogy between event horizon and entropy  entropy: disorder of missing information in a system  bit of information  area of the event horizon  definition of entropy and temperature is possible

9.  paradox: finite temperature  emission of thermal radiation??  Quantum mechanics: uncertainty principle  virtual particles can arise in pairs  they disengage for a short time and than annihilate  mass of the black hole decreases  total evaporation

10.  Only 3 observable characteristics: ◦ mass ◦ angular momentum ◦ electric charge  huge information loss  but a swallowed bit is ‘saved‘ in an area of the event horizon  like a hologram  3-dimensional object memorized by a 2- dimensional region