What you are describing is Astral Projection. It is an skill amongst witches, with consentration and meditation you can build up energy within and breach out of your physical body, thus the pyshical plane and passing through the Astral plane. That is the reason some witches can be with their loved ones in spirit or visit their past lives, uncover mysteries.
Research The stages to Alpha state.
I trust you, thats where your answer lies. -BLessed be.