Active materials such as bacteria, molecular motors and self-propelled colloids, are Nature’s engines. They continuously transform chemical energy from their environment to mechanical work. Dense active matter shows mesoscale turbulence, the emergence of chaotic flow structures characterised by high vorticity and topological defects.

I shall discuss how dense active matter might be harnessed to provide energy, and the relevance of mesoscale turbulence to cell motility and cell division. In particular I shall give examples where topological defects, which are important in the physics of liquid crystals, may be of relevance in biological systems.

Please note: The Colloquium Ehrenfestii takes place on Wednesday evenings starting at 19:30 hours in the main auditorium of the Oort building. Before the Colloquium, there is a common dinner in the canteen located on the ground floor of the  Oort building. The dinner starts at 18:00 hours sharp and is free of charge, under the condition that one attends the colloquium and that one has made a reservation before noon on the Tuesday preceding the colloquium. The registration form is only accessible from within the University (to block spammers); if you would like to register for the dinner from outside the University, please send an email to Kerkhof@physics.leidenuniv.nl. The revolving doors to the Oort building  are accessible until 9 pm after that they are locked and one should instead use the sliding doors directly adjacent to the Huygens building: these can be opened with an electronic key (seek help from locals).