Physical mediums are seeing the unresolved physical-emotional energy trapped within Space-Time, which is the energy (dark energy) which blocks our ability to perceive our surroundings correctly. So the physical medium may interpret a past event but not why the past event occurred which might bring a successful resolution and knowledge. They are simply transferring unresolved physical-emotional energy from one area to another.
What needs to be done is to find out when the event occurred and why the event took place in an attempt to some sort of resolution and knowledge.
Spiritual Side Through Judith L. Harper, 08/30/2014
(Comment: This is not easy by any stretch of the imagination. Usually it is a event or situation that no one wanted to deal with when it occurred or deal with it at any later date. Also research has to be done, and then find survivors and/or witnesses of the actually situation, or living relatives, who are then willing to tackle what is usually a difficult situation or event, in hopes of obtaining resolution.
If we don’t start tackling difficult and entrenched human issues we are absolutely going to be stuck with no forward movement in our spiritual journey).
SoulStates - Universal Spiritual Force 