People often ask if it is possible to change the past. A person usually asks this question because they want to erase or alter a negative or traumatic memory of a past event. I feel the past can best be understood and explained though the study of consciousness. I am a certified hypnotherapist. I feel hypnosis and self-hypnosis are incredibly powerful tools for exploring consciousness and the depths of our subconscious minds. I would say the past is a vague and ambiguous memory..