Wednesday 11 January 2012

Speaker: Prof Subir Sarkar (Oxford University)

Title: “Does dark energy exist?”


Abstract:

The Nobel prize in physics 2011 was awarded "for the discovery
of the accelerating expansion of the Universe" which is presumed
to be driven by a mysterious fluid with negative pressure 
('dark energy') which makes up ~3/4 of the Universe. In fact there
is no direct evidence for either acceleration or dark energy -
all inferences from the astronomical data are made assuming a specific
geometric model of the universe. The same data can be fitted in alternative 
toy models which have no dark energy. I will discuss a recent test for the 
dynamic effect of dark energy which has supposedly provided 5 sigma evidence 
but turns out in fact to be inconsistent at over 3 sigma with the standard 
cosmological model.