  This note summarizes a model-independent analysis of the age of the universe
problem that trades off precision in favour of robustness: The energy
conditions of Einstein gravity are designed to extract as much information as
possible from classical general relativity without specifying a particular
equation of state. This is particularly useful in a cosmological setting, where
the equation of state for the cosmological fluid is extremely uncertain. The
strong energy condition (SEC) provides a simple and robust bound on the
behaviour of the look-back time as a function of red-shift. Observation
suggests that the SEC may be violated sometime between the epoch of galaxy
formation and the present.
