Friday, June 18, 2004, 16:00
WHGA Auditorium
Prof. S. Sarkar, Univ. Oxford
Abstract:
Recent measurements of cosmic microwave background anisotropies by WMAP
have supposedly confirmed that the dominant component of the universe is
some mysterious vacuum energy, as had been indicated earlier by the
Hubble diagram of distant Type Ia supernovae. However this is based on
unproven assumptions about the nature of the primordial fluctuations
which give rise to the observed anisotropies; indeed an universe with no
dark energy can also fit the WMAP and large-scale structure data. We
will discuss direct tests for the presence of dark energy, in particular
the 'late integrated Sachs-Wolfe effect', and alternatives to cosmic
acceleration.