Frankfurt Institute for Advanced Studies

In this talk I will explain (a) what observations speak for the
hypothesis of dark matter, (b) what observations speak for
the hypothesis of modified gravity, and (c) why it is a mistake
to insist that either hypothesis on its own must
explain all the available data. The right explanation, I will argue,
is instead a suitable combination of dark matter and modified
gravity, which can be realized by the idea that dark matter
has a superfluid phase.