After a mid-morning break Dr Potzen led a discussion group. The LHC is looking for dark matter. It detects and adds up energy/momentum and “investigates” the missing stuff. The history of Dark Matter goes back to Einstein’s General theory of Relativity. In the integration a positive constant appeared indicating a push outwards due to gravity. Einstein originally didn’t like this and added a factor to get rid of it. He called this his greatest blunder. Possible explanations for the expansion ignoring dark matter could indicate that our gravitational laws need changing however gravitational lensing and the CBR negates this idea. Dark matter clumps together because of gravity. Our Solar System is stable. This limits dark matter flowing around. Not being able to see it we don’t know what the smallest object is. Computer models need the input of dark energy. Galaxies would rotate without dark matter but not as fast. Multiverse: Why do we have the fraction of dark energy that we appear to have. Too much and the universe would be pulled apart. Perhaps different universes have different strengths of dark matter in each one. Does quantum mechanics have the evidence? Some people don’t like this idea. Developing a model of the universe: What were the initial conditions? Observing and studying fluctuations. Inflation theory to generate ripples in space. What triggered the importance of dark matter? In the 1930s it was found that galaxies were moving faster than expected. The vacuum state of space is actually seething with energy which may explain why the universe seemed to appear from nothing. In his book “Cycles of time” Roger Penrose suggests that dark energy will eventually dominate and that any ripples seen now could be the imprint of previous universes. This theory is not taken seriously. Tiny black holes may be able to explain both dark matter and the cosmic background radiation. Ripples controlled by what is in the universe. Pressure opposes gravity but some “stuff” feels gravity but not pressure.