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8th International Congress of Serbian Society of Mechanics Kragujevac, Serbia, June 28-30, 2021 PROBLEMATIZING THE ORBITAL MECHANICS’ TWO FIRST INTEGRALS Slobodan Nedić University of Novi Sad, Faculty of Technical Sciences (retired from, in 2017) Dr. Zorana Đinđića 1, 21102 Novi Sad e-mail: nedics@uns.ac.rs, nedic.slbdn@gmail.com Key words: Kepler’s Laws, Kepler’s Equation (KE), Orbital Mechanics, Non-Conservativeness Extended Abstract: After Kepler’s formulation of the Three Laws/Rules with the Equation determining the timedependency of the Eccentric and intermediately the True anomalies, and Newton used them – along his first Two Laws and Huygens’ circular motion related centrifugal acceleration – to arrive at the with squared distance inversely proportional attracting central force as solely ‘governing’ the planetary elliptic trajectory orbital motion, the Orbital Mechanics has ever since been modeled by essentially non-oscillatory Non-Linear Differential Equations of the second order. In such situation, in order to solve for the orbital trajectories using initial position and the pertaining velocity, it was indispensable to resort to formulation of two independent 1st order NL-DEs – one per the degree of freedom: constancy of the sum of kinetic and potential energies – on one side, and the constancy of the angular momentum taken as by the radius swept area velocity, the latter thus implying zero-valued transverse acceleration, both as intrinsically central force features. Subsequently, through developments of Analytic and Rational Mechanics, the general principle of conservativeness was established, characterized by the zero-work done over a closed loop in a potential field – somewhat as the Perpetuity of the 3rd kind. While for the non-potential forces and situations with presence of dissipative forces the ensuing, notably Hamiltonian formalism has been duly modified, for the natural processes in chemistry and biology in particular, as well in cosmology, the presence of structuring and ‘negentropyc’ (“negative friction” and/or ‘precipitative’, the energy in-flow) phenomena largely have remained intractable. On the other hand, in the course of his four-years of tedious work on determining the Mars’ trajectory [1], guided by his own principle that every motion has its geometrical representation while the latter has to be ‘supported’ by the truly physical processes, Kepler has very early – at the very stage of the eccentric trajectory hypothesis – realized the necessity of presence of the mechanisms of both the attraction and repulsion, through his “Physical Astronomy”, rooted on Gilbert’s book De Magnete, assigning to the Sun’s virtus-motrics causation of purely circular motion and to a Planet – vis-insitia, the intrinsic ability to modify the very circular motion, [2]. Although this has been largely unaccounted for in the subsequent development of mechanics and dynamics, it had been followed by Leibniz with his by distance’s inverse cube explicit centrifugal force, Boscovich’s intermittent attraction-repulsion Curve, (Kepler-)Ermakov’s Equation, and by this author’s extension of the Thermo-Dynamical Oscillator concept of professor Vujo Gordić. These were the reasons for revisiting and scrutinizing the two foundational pillars of the Orbital Mechanics, in particular that it has strongly influenced all the branches of science: physics and cosmology, thermodynamics, non-linear complex systems dynamics, including mathematics. 1 S. Nedić, Problematizing the Orbital Mechanics’ Two First Integral It has been found that the Kepler’s (un)fortunate and essentially unallowable, but literally “life-rescuing” systematic modification of the Mars’ trajectory measured positions [1], despite his subsequent explanation that the Area law – valid for the angle(s) time-dependencies determined by his Equation – pertains to the solely Sun-governed circular motion, has led to the combining of circular (through the angular momentum, L = r 2 ϕ& , constancy and the resulting annulling of the && + 2r&ϕ& = L& / r ≡ 0 ) and rectilinear motions (through the constancy of transverse acceleration, rϕ total energy, which is nothing else than the definitional relation of the potential energy as the acquired and/or lost kinetic energy in the potential field) as orbital motion’s two Prime integrals. However, since the very presence of non-zero tangential acceleration in the observed trajectories of orbital bodies as well as in the produced solutions, the validity of the related First integral ‘status’ of both of these (otherwise, interdependent) quantities should have long been questioned. The above expression for transverse acceleration and the corresponding one for the total energy, Ξ = 0.5 ⋅ [ r& 2 + ( r ⋅ ϕ& )2 ] − µ / r , are given in the so-called “non-inertial coordinate system”, which has turned out to be rotationally-invariant to the rectangular one, so that the numerical integration in both, as well as the analytic-numerical evaluations, produce the same results corroborating the outgoing integrals1. However, when evaluating in the tangential-normal generalized coordinates (numerical integration will be pursued, too) the following is realized: 1. One gets the non-zero tangential acceleration, the projection of which on the transverse direction produces non-zero transverse acceleration, as shown in Fig. 1a for one period; 2. Integrating the gravitational force projection on tangential direction for the vertically scaled nominal ellipse with the pertinent KE, one gets the positive energy-well – Fig.1b. Fig. 1. Transverse acceleration and the work-done on the vertically scaled elliptic trajectory, all for e=0.75. Based on this, as well as the fact that there are numerous situations where the (closed) elliptic trajectories with two central or non-central forces do not obey the area-law and Kepler’s equation, the principle of conservativeness should be reconsidered and possibly be altogether abandoned. References [1] Lancaster P., E.J. Aiton, The elliptical orbit and the area law, Section 10.5 in Vistas in Astronomy, Vol. 18, 1975 – Proceedings of the Quartercenteniary of Kepler’s birth. https://www.dropbox.com/sh/p0yav5jfmdpfv1x/AADBVkKMQiFU4dtNyeyFIjuka?dl=0 [2] Nedić S., Kepler's Equation and Angular Momentum – Historical Perspective, Critical Analysis and Implications for Developments in Mechanics, Mathematics and Physics, arXiv 2020. && , the later In [2] an error had been made resulting in ‘+’ instead of ‘-‘signs in the expressions for &r& and ϕ having resulted in non-zero valued transverse acceleration; also, used a=1+e produced the varying energy. 1 2