Lau, A. W. C.Hoffman, Brenton DCrocker, John CDavies, A.Lubensky, Thomas C.2023-05-222023-05-222003-11-032005-12-02https://repository.upenn.edu/handle/20.500.14332/5843We report the first measurements of the intrinsic strain fluctuations of living cells using a recently developed tracer correlation technique along with a theoretical framework for interpreting such data in heterogeneous media with nonthermal driving. The fluctuations’ spatial and temporal correlations indicate that the cytoskeleton can be treated as a course-grained continuum with power-law rheology, driven by a spatially random stress tensor field. Combined with recent cell rheology results, our data imply that intracellular stress fluctuations have a nearly 1/ω2 power spectrum, as expected for a continuum with a slowly evolving internal prestress.Article