Parallax, the change of the position of objects on the sky with time, was
proposed as a cosmological test in 1935. The Gaia satellite, launched in
December 2013, will probe parallax on cosmological scales for the first
time. I will discuss the theory of cosmic parallax and explain how it can
be used to test the FRW metric without any assumptions about the matter
content or the gravitational field equation.
ct: Kjell Rosquist
