"The pushing out force was clearly established by Henry Cavendish over 200 years ago."

Cavendish demonstrated a force pulling things together.

He didn't have anything massless to work with (and we still don't).

Hello B c,

I see, you never heard of Cavendish’s most famous torsion-bar experiment. Very surprising with all those posts behind you.

With his torsion-bar, Cavendish in 1798 established that two bodies separated by a distance attract each other due to gravitation, and he also established that when their masses are ignored the force of gravity in-between them becomes negative. That is, two hypothetical mass-less spheres in free space repulse each other at a finite speed of 3.335x10

^{−9} for a total velocity of removal of 6.67x10

^{−9}. We are here talking of the universal gravitational constant (G).

Actually Cavendish performed his experiment in the quest to find the Earth’s density. However, after measuring the force, masses, and distance; the density, the universal gravitational constant (G) as well as the acceleration of gravity at the surface of the Earth could be calculated. Please note, in order to calculate (G), Cavendish took away the weight of the two small lead spheres which weighted 0.73 kg each.

If you google “Cavendish experiment”, you may see that with the torsion-bar Cavendish used two small and two large lead spheres.

To show the negative nature of (G) here is Newton’s formula for the force of gravity:

m

_{1} m

_{2}F = G ————

d

^{2}the equation in question consists of five members: the force of gravity, the constant G, the distance between the Earth and the Sun (d) and two body-masses, one of the Earth (m

_{1}) and the second one of the Sun (m

_{2}). If we care to solve the equation as it stands and then solve it once more without the constant G, we shall find, even if very small, a difference between the latter and the former solution corresponding to the universal gravitational constant which we have purposely excluded the second time around and which, strictly speaking, is the sum total of the effect of the constant G spread all along the distance between the Earth and the Sun. This clearly shows that Cavendish's constant is a repulsive force whose absence would create a much stronger force of gravity between the Earth and the Sun, strong enough, I may add, to force our wonderful planet to fall spiralling towards the Sun in a matter of days.

I doubt he would have been able to observe anything moving at "6.67x10^{−9} metres per second".

If your doubts are based on that year 1798, think again. The torsion-balance is still in vogue and in SI units, for an obtained Earth’s density of 5.448 g cm

^{−3}, Cavendish's value gave 6.75x10

^{−11} N m

^{2}/kg

^{2} which differs by only 1% from today’s currently accepted value of 6.67259x10

^{−11} N m

^{2}/kg

^{2}.