URL: https://physikseminar.desy.de/zeuthen/past_colloquia/colloquia_in_2008/jul_9_2008/@@siteview
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Dark Matter - A Cosmic Mystery
Christof Wetterich (Universität Heidelberg)
Seminar Room 3, 15:00
Dark energy - a homogeneously distributed cosmic energy density - seems to
explain various cosmological observations. The anisotropies in the microwave
background radiation, the formation of structure and the late time
acceleration of the Hubble expansion fit into a consistent picture.
The role and origin of dark energy are among the greatest mysteries in
fundamental physics, touching the question of unification of gravity with the
fundamental quantum interactions.
We discuss quintessence - a dynamical form of dark energy - and
possible signatures distinctive from a cosmological constant. In particular,
we address the possibility that the time evolution of a cosmological scalar
field can be stopped by an increasing mass of the neutrinos. This leads to a
transition from a cosmological scaling solution with dynamical dark energy at
early time to a cosmological constant dominated universe at late time. The
trigger for the transition is set at the time when the neutrinos become
non-relativistic , corresponding to a redshift z ~ 5 , explaining why dark
energy becomes important now. The dark energy density is related to the mass
of the neutrinos.
Quintessence could be related to a new "fundamental" macroscopic force and
induce a small time variation of fundamental constants.
