Hubble constant.
16 BLY away stars go away at c.
Thats the edge of the VISIBLE universe.
Outside the visible universe stars go away faster than c with respect
to our center of our universe. But its universe has the same laws w do
and a photon is c .
Dark Energy is spacetime is 0 wavelength at c. The photon will pass
you at 0 wavelenth at c.
The only empty space is where a partical at c in orbit of atoms takes
up space wile at c.
Thats mass and more motion is more empty space more low .
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Gravity is the shape of the atom wile all its parts orbit the center of
G , an eliptical orbit has a center of mass and a center of gravity.
F is the distance from the center of gravity to the center of mass.