Reconstructing the History of Energy Condition Violation from   Observational Data
  We study the likelihood of energy condition violations in the history of the Universe. Our method is based on a set of functions that characterize energy condition violation. FLRW cosmological models are built around these "indication functions". By computing the Fisher matrix of model parameters using type Ia supernova and Hubble parameter data, we extract the principal modes of these functions' redshift evolution. These modes allow us to obtain general reconstructions of energy condition violation history independent of the dark energy model. We find that the data suggest a history of strong energy condition violation, but the null and dominant energy conditions are likely to be fulfilled. Implications for dark energy models are discussed. 
Chao-Jian Wu (BNU/NAOC), Cong Ma (BNU), Tong-Jie Zhang (BNU/PKU)
astro-ph.CO gr-qc