1. A method of imaging internals of a physical object using acoustic waves, comprising: a) transmitting an acoustic wave field toward the object; b) receiving a resultant acoustic wave field with a receiver, wherein the resultant acoustic wave field is in response to the transmitted acoustic wave field reflected from or transmitted through the object; c) determining a predicted resultant acoustic wave field derived from a model of the object; d) determining a residual between the predicted resultant acoustic wave field and the resultant acoustic wave field; and e) back propagating the residual to determine corrections to the model of the object.