Abstract
Observations firmly established that the 70% of our universe consists
of dark energy, while a further 25 % of dark matter. The nature and
origin of both dark components form some of the biggest puzzles in
modern physics. Data suggest that on cosmological scales, dark matter
behaves like dust, while dark energy mimics vacuum – or Einstein’s
cosmological constant. The apparent simple cosmological dynamics may
be deceptive and hide complicated degrees of freedom. In this project,
we introduce novel tools towards understanding the nature of both
components on galactic and shorter scales. In particular, we
focus on the general frameworks of i) kinetic gravity braiding
theories, as the only class of nontrivial single scalar-field models
consistent with the recent measurement of gravitational wave speed and
ii) superfluid dark matter which may solve the puzzles of galactic dynamics.