The Force of Gravitation

Introduction - Modern Science

"A theory of gravitation - the universal attraction that massive bodies exert on each other, the prime mover of the planets about the sun and of the moons about the planets - created by Newton, stands at the cradle of modern exact science. Another theory of gravitation, the work of Einstein, represents one of the proudest achievements of twentieth-century theorizing. Through hundreds, even thousands of years of history, men have observed and measured the effects of gravitation, have endeavored to turn it to their own use, to overcome the limitations imposed by it, and more recently, to control it with extreme precision in the course of their first steps into the depths of space."

Peter G. Bergmann, The Riddle of Gravitation - Dover Edition, 1992

Mainstream Science Hypotheses

  • Standard modern scientific Gravitation theories are based on the existence of a gravitational field permeating the whole universe, and which interaction is carried by a specific particle, the graviton.
  • General relativity model predict the existence of gravitational waves induced by gigantic space events like stars collapsing and generating black holes, or stars/galaxies collisions.
  • Albert Einstein Theory of Gravitation has transformed the inertia as a fictitious force, removing it from the mathematical model description of the behavior of matter.

Current problems

  • The graviton has never been experimentally observed
  • Kepler/Newton models do not account for galaxies peripheral stars which should have been ejected from their orbits, based on their observed orbital speeds. Orbital motion is well understood. Orbital movement is the result of the balance between the gravity force and the inertia force. Orbital velocity is a direct function of the distance between the two bodies, and it decreases when the distance (r) increases above a threshold (v = square root(GM/r)). It is confirmed at the scale of our planetary system. The orbital velocity of the earth is around 30 km/s where Jupiter's orbital velocity is around 13.3 km/s. But, at the scale of a galaxy, this rule breaks down : at an orbital speed of 2 x 10-10 m/s2, it does not decrease as expected (see diagram). Dark Matter concept was invented to keep the model consistent, but it cannot account for others movements like globular clusters.
    Other models have also been proposed to accommodate this observed behavior - see the MOND theory. But MOND has also problems with globular clusters behaviors and it remains an empirical model, not a theory. However, it may contain some clues : the value of the threshold where orbital speed (a0) diverge from the theorical newtonian model is close to the product of the speed of light (c) by the Hubble constant (H0).
    Recently (M.E. McCulloch - 2014), a new theory was announced, the MiHsC (Modified Inertia by a Hubble-Scale Casimir Effect), which postulate (and demonstrate) that the inertia mass may be different from the gravitational mass, due to the assymetric Casimir effect. This phenomenon would , above the a0 threshold, decrease the inertia mass as a function of the acceleration of the orbiting body.
  • General Relativity Model do not account for the acceleration of the expansion of the visible universe. Dark Energy was invented to keep the model consistent. The MiHsC theory explains also this accelerated expansion without any Dark Energy.
  • Gravitation Theories cannot be reconciled with Quantum Physics
  • Inertia is still alive

Some thoughts

Sir Isaac Newton - PRINCIPIA - Rules of Reasoning in Philosophy

  • RULE I - We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.
  • RULE II - Therefore to the same natural effects we must, as far as possible, assign the same causes.
  • RULE IV - In experimental philosophy we are to look upon inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.

Sir Isaac Newton - PRINCIPIA - General Scholium

This Being governs all things, not as the soul of the world, but as Lord over all; and on all account of his dominion he is wont to be called Lord God, or Universal Ruler; for God is a relative word, and has a respect to servants; and Deity is the dominion of God not over his own body, as those imagine who fancy God to be the soul of the world, but over servants. The Supreme God is a Being eternal, infinite, absolutely perfect; but a being, however perfect, without dominion, cannot be said to be Lord God; for we say, my God, your God, the God of Israel, the God of Gods, and Lord of Lords; but we do not say, my Eternal, the Eternal of Israel, the Eternal of Gods; we do not say, my Infinite, or my Perfect; these are titles which have no respect to servants. The word God usually signifies Lord; but every lord is not a God. It is the dominion of a spiritual being which constitutes a God: a true, supreme, or imaginary dominion makes a true, supreme, or imaginary God. And from his true dominion it follows that the true God is a living, intelligent, and powerful Being; and, from his other perfections, that he is supreme, or most perfect. He is eternal and infinite, omnipotent and omniscient; that is, his duration reaches from eternity to eternity; his presence from infinity to infinity; he governs all things, and knows all things that are or can be done.
... Hitherto we have explained the phenomena of the heavens and of our sea by the power of gravity, but have not yet assigned the cause of this power. This is certain, that it must proceed from a cause that penetrates to the very centers of the sun and planets, without suffering the least diminution of its force; that operates not according to the quantity of the surfaces of the particles upon which it acts (as mechanical causes used to do), but according to the quantity of the solid matter which they contain, and propagates its virtue on all sides to immense distance, decreasing always as the inverse square of the distances... But hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses; for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy."