Matter

Souls that aren't bound to the material life no longer exist in a material way. Energy is not obstructed by material and therefore it can move freely even through material. Souls travel at the speed of light through the universe (although it is still bound by the borders of time). Because our earth is relatively small a soul can move itself from one place to another on earth in the wink of an eye. A Soul can also travel to other places within our universe and possibly start a new material life over there.

Sometimes a soul wants to transfer a message to the material world. To do so they need a medium. The strength of the soul decides what its possibilities are. The more experienced the soul is the better it can make use of the chosen medium. A highly evolved soul can therefore use a medium much easier than an lower evolved soul.

The medium is most qualified when it's affected by electromagnetic influences. A soul is able to generate electromagnetic radiance. Such are used in tape-recorders (magnetic recording head), televisions (influencing the cathode ray), etc. Even a human medium can receive this radiation.