Primordial equation of state transitions

We revisit the physics of transitions from a general equation of state pa- rameter to the nal stage of slow-roll ination. We show that it is unlikely for the modes comprising the cosmic microwave background to contain imprints from a pre- inationary equation of state transition and still be consistent with observations. We accomplish this by considering observational consistency bounds on the amplitude of excitations resulting from such a transition. As a result, the physics which initially led to ination likely cannot be probed with observations of the cosmic microwave back- ground. Furthermore, we show that it is unlikely that equation of state transitions may explain the observed low multipole power suppression anomaly.