Invited_talk abstract details

In the last ten years, observations have established that the Universe has entered an epoch of accelerated expansion. The measured values of matter and dark energy densities (the latter, driving the expansion) require a fine tuning of the initial conditions of about 96 orders of magnitude. In this talk we explore the solutions that have been put forward to solve this so called 'coincidence problem' in terms of a coupling between dark matter and a scalar field. We pay special attention to observational test that are sensitive to the existence of such coupling. We show that a statistical comparison of model predictions with observation does not lend support to these models. After 10 years of the discovery of the accelerated expansion, the 'coincidence problem' is still an open question.