One of the more interesting features of Newton’s Laws of Motion lies in the definition of a ‘body’ or ‘object’. Newton’s Law of Gravitation, for example, involves the mutual attraction of two objects separated by a space. But this space is not devoid of matter though in Newton’s time it was believed to be so when dealing with the motion of, say, the Moon with respect to the Earth. Newton’s laws are often described as billiard ball mechanics.
Newtonian objects or bodies are thus autonomous clumps of matter bounded by an enclosing surface. An airplane in the sky is thus a Newtonian object but not the atmosphere in which it is immersed. The Earth’s core and mantle are also not Newtonian objects because both lack autonomous movement; they are parts of the Newtonian object we call the Earth.
Furthermore modern science has extrapolated Newton’s gravitational theory to explain the process of matter accretion to form stars and planets, proposing the phenomenon of self-gravitation to explain the existence of high pressure-temperature mineral phases inside stars and planets. However self-gravitation has a problem – it’s quite fictitious.
Consider an initial two body example where the bodies m1 & m2 are separated by a distance ‘d’. Because of mutual attraction both are attracted to each other and will afterwards become joined together. When d, distance, becomes zero, we have a new body/object comprised of the combination of m1 and m2, m3.
But because d=0 no further attraction occurs between m1 and m2 because we are no longer dealing with two autonomous bodies or objects, but are faced with the presence of m3, a single body but comprised of m1 + m2.
We do not observe any motion between m1 and m2 because they now have joined together to form m3, Newton’s laws of motion therefore no longer apply to m1 and m2 because these two bodies are no longer autonomous objects or bodies.
We do not observe m1 and m2 continue moving towards each other until they coalesce into m3 either, though we seem to think so because how else could high pressure/temperature phases exist inside planets and suns?
Self-gravitation is simply the result of the logical fallacy of arguing the consequent.
The only natural force that can produce high pressure/temperature phases is the plasma Z-Pinch mechanism.
This leads to the speculation that gravity might be a surficial phenomenon of electricity.
But there is no such thing as self gravitation.
Update: Matter or mass accretion – study the three-body problem which shows that the system develops into chaotic motion and then wonder how mass accretion happens to work — it doesn’t.