Finite-size transitions in membranes

The lipid raft hypothesis states that cellular membrane keep their composition close to a critical point. Most detractors of this hypothesis have raised an important point: maintaining such a composition for the hundreds of components in cell membranes would require extensive feedback mechanism that are still elusive. In this talk, I will show that by carefully extending the 2D Ising model to N states, finite-size effects drive the system to adopt a critical composition. Similar to biological cells, the overall composition can slowly drift along a critical manifold.