On Aug 30, 2:35*pm, Cecil Moore wrote:
On Aug 30, 12:57*pm, Art Unwin wrote:

Thus the exercise starts with Earth itself and then one determines the
next medium and so on until one reaches the outer Galaxy.

Visible energy/matter can occupy the same space as dark energy/matter,
much like solid salt and water can occupy the same space. Just as the
salt contributes to the mass contained in the water, visible mass
contributes to the mass occupied by dark matter.
--
73, Cecil, w5dxp.com

Since you are so familiar with the concept why not start from Earth
with a progression until you get to Aether. I don't think you will get
to your favorite "dark matter" For that matter explain what a "medium"
is in physics terms.