Turbulent flows are encountered ubiquitously in nature and technical applications. For example, flows over an airfoil or water flows through pipelines have a chaotic spatial structure and are highly time-dependent. In general, the transfer of fluids is energetically far more efficient if thefluid motion is smooth, since friction losses are much lower. Therefore the transition from laminar to turbulent flow poses a challenge of great practical and theoretical importance. The aim of this proposal is to advance the understanding of the onset of turbulence in pipe flow by investigating (i) the boundary between the laminar and the turbulent flow, which is believed to be governed by coherent flow structures, so-called edge states and (ii) the mechanism that sustains and expands turbulence contaminating the laminar flow.To address the transition to turbulence in pipe flows, the fellow will perform laboratory experiments and numerical simulations at the Max Planck Institute for Dynamics and Self-Organization (MPIDS). The results will be used to test and extend current theoretical predictions, which stem from modern concepts of dynamical systems and hydrodynamic stability. The expected results would not only shed light on the energetic mechanisms that sustain turbulence, but also furnish the basis for new strategies to control turbulence in pipe flow.The fellow's previous experience on the topic of laminar-turbulent interfaces and in experimental and numerical approaches provides a suitable background to learn the new skills needed to attack the complex phenomena encountered in transition to turbulence. The new scientific skills gathered at MPIDS together with communication and mentoring skills will render the fellow in an outstanding position to obtain a tenured position following the completion of the proposed research. The proposed research work with the scientifically established group of Dr. Björn Hof in Göttingen will be a crucial step towards this aim.