Inertia and Gravitation: From Aristotle's Natural Motion to Geodesic Worldl

As usual, Petkov's does an excellent, didactic effort to orient -- or reorient -- the reader in the jungle of terms, used and abused by many authors in the multitude of books on relativity... Terms such mass, force, inertia, inertial forces, inertial energy, kinetic energy, geodesic hypothesis, gravitation, origin of inertia, 4-dimensional stress and many more, which have lead astray so many students of relativity.Via the 2 major themes, Inertia and Gravitation, he gives a most complete and clear treatment of the main problems & incomprehensions faced by many students, in the vein of Kevin Brown (1500 pages) , but in less than 140 pages !A word of caution though : the reader may be puzzled by Petkov's constant use of the expression "absolute" acceleration whereas he really means "detectable" acceleration... He should have insisted on that point as he did in his book "Relativity and the nature of spacetime", thereby avoiding the reader's potential identification "absolute = invariant = frame independent"...

The author introduces a complex and potentially confusing subject through the use of an historical perspective. Potential readers should not be intimidated by the title. The author writes clearly and explains the concepts well even for beginners. Those among us who already have a background in physics will not be disappointed as more advanced topics are also covered. The author clearly has a background in both physics and philosophy which helps him in presenting the conceps in a wider context.

The laws of motion and of gravitation are described according to evolving perspectives, from Aristotle, through Galileo and Newton, to Einstein and Minkowski. Written by a devoted Minkowski enthusiast, the survey is always informative, though at times biased and ultimately unorthodox.It is shown how Newton's theories worked superbly in accounting for motion in both inertial and gravitational frames, even though Newton himself was sceptical about the action-at-a-distance implied by forces of gravity. Mach's misconceived attempt to invoke an absolute basis for acceleration is also analysed.Einstein's special relativity theory addressed the inability of Newton's laws to incorporate electromagnetic radiation. Relativity is further analysed in terms of Minkowski's spacetime geometry. The ability of this representation to distinguish definitively between inertial and accelerated motion is explained, as are the phenomena of length contraction and time dilation for observers in relative motion.Einstein's extension of spacetime into curved coordinates to cope with gravitational phenomena is clearly illustrated, but it is concluded that gravitational attraction does not exist, whatever Einstein believed.In an appendix, the author proceeds to use the geodesic hypothesis not only to explain the source of gravitational forces and energy, but also to explain them away. Theories of quantum gravity cannot be devised, he asserts, because there is nothing to be quantised; people working on such theories (I suppose he includes Lee Smolin here) are doomed to failure; gravitational waves do not exist (projects LIGO, LISA and its successors are a waste of effort); the decaying orbit of twin neutron stars PSR 1913+16 is better explained by tidal friction than by the mistaken belief in gravitational energy; and so on.Scarcely mentioned is that although non-Euclidian spacetime can account for inertial motion more precisely than Newtonian theory, that is only half the story of general relativity. The way in which mass tells spacetime how to curve is the other half, but this aspect of gravitational interaction is abruptly dismissed in a couple of lines in the closing pages of the book.A book of two halves, then; one of which is good, the other unconvincing. Special relativity and Minkowski geometry are already covered in other excellent books, including those of David Bohm and N. David Mermin.

A book, by Vesselin Petkov about seemingly complicated physics explained in such a way that a lot of people can read and understand things.

L'auteur, à la fois physicien et philosophe, développe une interprétation de l'inertie et de la gravitation différente de celle habituellement admise, interprétation différente qui s'appuie sur une re-lecture du texte de H. Minkowski << Espace et Temps >>.Ce qui le conduit à considérer que l'interaction gravitationnelle n'existe pas et qu'on ne peut donc la quantifier. Ce qui expliquerait que, malgré bien des efforts, de brillants physiciens n'ont pu parvenir, depuis des dizaines d'années, à quantifier le champ gravitationnel.V Petkov est un des membres fondateurs de l'Institut de Recherches Fondamentales Hermann Minkowski.Ses explications, qui restent accessibles,devraient intéresser, non seulement les chercheurs, mais aussi les enseignants.