%0 Journal Article %T Length spectra and degeneration of flat metrics %A Moon Duchin %A Christopher J. Leininger %A Kasra Rafi %J Mathematics %D 2009 %I arXiv %R 10.1007/s00222-010-0262-y %X In this paper we consider flat metrics (semi-translation structures) on surfaces of finite type. There are two main results. The first is a complete description of when a set of simple closed curves is spectrally rigid, that is, when the length vector determines a metric among the class of flat metrics. Secondly, we give an embedding into the space of geodesic currents and use this to get a boundary for the space of flat metrics. The geometric interpretation is that flat metrics degenerate to "mixed structures" on the surface: part flat metric and part measured foliation. %U http://arxiv.org/abs/0907.2082v1