The Naked Scientists–June 2012

The second lecture was given by Dr Andrew Pontzen from the University of Oxford about the beginnings of the universe. Dr Pontzen is a theoretical astronomer and uses very powerful computers in the UK and USA.

050

He started the lecture by showing an excerpt from one of his videos http://www.cosmocrunch.co.uk/?page=talk

The Cosmic microwave background image defines what we know from the big bang.

CMB

Immediately after the Big Bang the early universe underwent an extremely rapid exponential expansion. Quantum fluctuations (1 part in 10000) in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the universe. The CMB is a generally uniform glow indicating that the universe expanded equally in all directions from a point. Pattern of waves predicted and seen gives us information on what is in the universe. Only 5% of the matter in the universe we can see (0.5% of this are stars). 23% is dark matter (behaves like particles). 72% is believed to be dark matter (a force we don’t understand and that pushes things apart).

universe today

Computers can simulate the universe creation. Dark Matter feels the force of gravity and the computer simulates what it does. The virtual universe needs tiny ripples to allow Newton’s equations to work. Stuff collects together due to dark matter. The green colour in the simulation shows dark matter. The hierarchical model proposes that galaxies form and evolve through successive mergers of smaller bodies and their fate is more dependent on the environment which they inhabit. Modelling makes assumptions. Dark energy only kicked in at a late stage of universe creation (earlier on dark matter was more important). No one has detected dark matter yet. Progress has to come from theory first. Combining thermodynamics and gravity gives some weird answers such as negative heat capacity. What is the connection between matter and black holes? There is a supermassive black hole at the centre of our Solar System.

Dark matter and Dark energy are considered to be interchangeable – E=mc^2. The Large Hadron Collider is looking for either but hasn’t found them – yet.

References: http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation http://en.wikipedia.org/wiki/Inflation_(cosmology) http://www.jeffstanger.net/Astronomy/galaxyformation.html http://motls.blogspot.co.uk/2009/01/myths-about-thermodynamics-and-gravity.html

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