#### Kaiduorkhon

**Registered Senior Member**

I wish to cite at this time what is to say the least, a most interesting alternative concept concerning the identity of (what Newton was always careful to call 'universal') gravity. An otherwise completely ignored statement which might even be correctly categorized as 'obscure', or 'inconsequential'. Were it not for the fact that this statement is made by Sir Isaac Newton. And, were it not for the fact that this statement is included in the very (3 page, non-mathematical) Preface to The PRINCIPIA MATHEMATICA.

From the beginning of the 1st to the end of the 2nd page of Newton's three page Preface to The PRINCIPIA MATHEMATICA, Newton is discussing the motions of falling objects and orbiting planets. By way of his applied mathematical descriptions of the effects of the force of gravity. At this time, Newton offers the following statement about what causes the gravitationally induced motions of planets & apples, quote:

*“For I am induced by many reasons to suspect that they may all depend on certain forces by which the particles of bodies, by some causes hitherto unknown, are either mutually impelled towards each other, and cohere in regular figures, or are repelled and recede from each other; which forces being unknown, philosophers have hitherto attempted the search of Nature in vain."*

That quote and its extraction will henceforth be referred to here, as THE GRAVITATIONAL ALTERNATIVE. Not my gravitational alternative; Newton's Gravitational Alternative to be exact. I repeat the quote (of particles and systems-of-particles: of matter), 'are either mutually impelled towards each other and cohere in regular figures (orbits; juxtapositions), or, are mutually repelled and recede from each other .'

It implies directly and categorically, that gravity may in fact be the opposite of the universally considered impelling or 'pulling force of attraction'; that is to say, Isaac Newton and his formal definitions, directly and resolutely suggest that gravity may in fact be a repelling or pushing force.

It is difficult to over dramatize the very existence of this statement, its author, and especially its contextual implications. It categorically allows that everything Newton mathematically confirms and describes in The PRINCIPIA MATHEMATICA - from orbiting planets, falling apples, aquatic, terrestrial, and atmospheric tides - all the large and small phenomena of gravity - is caused by one of two kinds of forces: the conventionally considered impelling or pulling force of attraction, or, its exact opposite, a repelling/ pushing force. That is fact #1.

Fact #1 evokes at least one question: Allowing possible advantage in Newton's Gravitational Alternative that gravity may in fact be a repelling (pushing) force rather than an impelling (pulling) force, how might any such advantage be experienced and applied?

:bagpuss:

That question and its derivation might still be deemed obscure and inconsequential, if its direct unequivocal answer did not exist, most profoundly, at the heart-foundation of the latest and most advanced generalized theory of gravity in the history of Physical Science. That being Albert Einstein's GENERAL THEORY OF RELATIVITY.

In the first quarter of this century, Albert Einstein, in observing the already well known inversely proportional equivalence of gravitational and inertial mass values (which will be explained, shortly), described this equivalence as: 'an astonishing coincidence', and then applied the cause of his astonishment to the monumental task of formulating an unprecedented theoretical generalization concerning the identity of gravity. That, being none other than the General Principle Of Relativity; which principle is quite literally the foundation upon which rests Einstein's entire General Theory of Relativity. The most advanced statement about gravity, to date.

The General Principle is also misnomered as the 'Equivalence Hypothesis', or, more appropriately, 'The Principle Of Equivalence', which states:

*'There is no way to distinguish the effects produced by the inertial force of acceleration (a pushing/repelling force) from the effects produced by gravitational force (assumed to be a 'pulling/impelling force: identity unknown')'.*

Regards,

Kaiduorkhon

http://forums.delphiforums.com/EinsteinGroupie