_{1}

Recent measurements have shown that gravitational waves and thus the gravitational interaction propagate with the speed of light. The propagation delay of the gravitational interaction in orbiting systems couples the orbital and center of mass motions. This causes the orbits to spiral out and the center of mass to accelerate. It is one of a number of small effects modifying the Kepler orbits. The calculations show that the analytical describable expansion of the semimajor axis started at a time that is less than the age of the systems. This could be caused by a collision of a system component in the past. The effect of this propagation delay on the motion of the Earth Moon and the Brown Dwarf 569Bab binary star system is analyzed. These systems were chosen because a considerable amount of measured astronomical data is available. The calculated results are in excellent agreement with the measured data. In galaxies, too, the energy transfer from the orbit of the star cloud to the center of mass motion causes the galaxies to ac-celerate. If galaxies are considered to be molecules of the universe, then the acceleration of the galaxies will cause the molecular gas to heat and expand. Alternatively, the loss in orbital internal energy of the galaxies should be included in the mass and energy in the calculation of the expanding Universe.

The small effect of the propagation delay of the gravitational interaction on the motion of the Earth Moon and the Brown Dwarf 569Bab binary star system is analyzed. The calculated values are in very good agreement with observed values.

Recent measurements have shown that gravitational waves and thus the gravitational interactions propagate with the speed of light. This is described by B. P. Abbott et al. [

The gravitational propagation delay exists whether the interaction is modeled by the deformation of the four dimensional space due to the mass of the bodies, or it is modeled by a gravitational interaction that is propagating between objects. In each case a change in position of one object takes time to be sensed by the other object.

Neither Newtonian Classical Mechanics nor the General Theory of Relativity considers delayed interactions [

The systems considered here are neither extremely massive, by astronomical standards, nor do they move with velocities that are a substantial portion of the speed of light. For such systems the Kepler-Newtonian Mechanics [

The finite propagation delay of the gravitational interaction couples the orbital and center of mass motions. The main effect of the delay in the gravitational interaction is that the orbits grow very slowly. The loss in orbital energy is transferred to the center of mass motion. This causes the center of mass to accelerate. The acceleration is not linear since part of the orbital angular momentum is transferred to the center of mass motion.

In galaxies, too, the average propagation time of the gravitational interaction between the star cloud and central black hole is much smaller than the orbital period of the star cloud. Thus, the effect of the gravitational propagation delay on galaxies should also exhibit a growth of the distributed star cloud and an acceleration of the center of mass.

One can consider the very large number of star systems, galaxies, and galactic clusters as molecules of the universe. The transfer of internal orbital energy to the molecular motion will cause the universe gas to heat and expand. Alternatively, one should include the loss in orbital internal energy of the galaxies and other orbiting objects in the mass and energy of the universe when considering its accelerating expansion [

After completing its final run, scientists at the extremely sensitive Large Underground Xenon (LUX)?Zeplin [

Perhaps Dark Mass is like the Ether of the end of the 19th century through which electromagnetic waves were supposed to propagate. The Michelson Morley experiment showed in 1887 that the aluminiferous Ether does not exist. These experiments were repeated with greater and greater accuracy until 1920 without detecting an aluminiferous Ether. In 1905 Einstein showed that the aluminiferous Ether was not necessary for electromagnetic wave propagation.

There are a number of small corrections to the Kepler Newton model:

For the Earth Moon system there are interactions with the sun and the other planets. This effect mainly results in a small change of the orbit and in the Apsidal precessions of the orbits [

There is an increase in the orbits explained by tidal effect [

There are small effects due to the curvature of space near masses explained by the General Relativity Theory [

Here the small contribution to the orbital motion due to the finite propagation delay of the gravitational interaction is calculated. The calculated values are in very good agreement with observed values.

Another result is that the analytically describable spiraling out of the semimajor axis starts at a time that is much less than the age of the system. This probably can be caused by a collision of one of the system components that obscured the previous analytical describable motion. The time of the past collisions is calculated. The spiraling out of the Lunar orbit, analyzed here, starts in the Pliocene and Miocene epochs, long after the Dinosaurs have disappeared.

The gravitational interaction is an attractive force. In this case the force points in a direction opposed to the direction it travels. It can be demonstrated that the delayed gravitational interaction is completely causal as shown in

A force FRthat was radiated by the Earth in the past is received currently by the Moon. This is a Retarded force.

The Moon radiates a force FAcurrently that the Earth might or might not receive in the future. This is an advanced force.

By Newton’s law of action and reaction the Moon experiences a recoil force FRecoil_{}equal in magnitude and opposed in direction to the force FAit radiated. The recoil force is independent whether or not the Earth receives the radiated force in the future. The forces are continually radiated and received.

Two forces act on the Moon. The force FRradiated by the Earth in the past and the recoil force FRecoil. These two forces are equal to the mass of the Moon times its acceleration. Thus, the formulation is causal.

S. Carlip [

with Newtonian gravity with a light-speed propagation delay added in. .... it is known that Solar System orbits would shift substantially on a time scale on the order of a hundred years.” The calculations that led to this erroneous conclusion only used the retarded part of the interaction. To correctly calculate the motion of a system where the interaction propagates with a finite velocity between objects both the retarded and re- coil parts of the equation of motion have to be used. The recoil force is equal in magnitude to the advanced force. In the delayed gravitational interaction the recoil terms cancel the first order terms of the retarded terms leaving only small second order terms. Thus, a few percent shifts in the orbits occur in the order of 10^{7} years. As discussed above, the apparent non causal advanced term is actually equal to a causal recoil term by Newton’s principal that states that for every action there is an equal and opposed reaction.

The use of both retarded and advanced terms also preserve the time inversion symmetry of Newtonian mechanics. Indeed, references discussed below [

A delayed interaction central force problem for electrical charges has been discussed by many eminent scientists including Carl Friedrich Gauss (1845), K. Schwarzschild (1903), W. Ritz (1908), H. Tetrode [

Carl Friedrich Gauss in 1845 was the first scientist recorded to discuss interactions at a distance that propagate with a finite velocity.

Electromagnetic Theory texts discuss the force on an accelerating charged particle due to the radiation emitted by it [

Newtonian Mechanics works exceedingly well in providing a mathematical model for a very large number of physical phenomena. However, there are physical phenomena where the Newtonian mathematical model is insufficient [

For the calculations of the motion of the components of our machines made by humans and robots we use the surface of the Earth as an inertial reference. The acceleration of the surface of the Earth is small compared to accelerations of the machine components. The Earth surface moves because the Earth spins about its axis, it orbits about the Sun, the Sun orbits about the galactic center which also is not stationary. There is no absolute stationary reference in the universe.

The center of mass of most systems orbit about some other object such as a star for a moon planet system or the center of a galaxy for star systems. One can approximate this parent system as being an inertial reference frame. The orbital velocity of this parent system is assumed to be constant and uniform for the duration of one cycle of the system whose motion is being analyzed.

For the calculation of the Moon Earth system the center of mass of the Earth Sun system is used as the approximate inertial reference coordinate system. The center of mass velocities of the Earth Sun system are assumed to be approximately constant. It is further assumed that the center of mass of the Earth Sun system moves slowy compared to the orbital motion of the Moon Earth system. This is similar to the Born Oppenheimer approximation [

The motion of the objects with a delayed interaction can be derived from a method similar to the Euler Lagrange model. One can develop a causal Lagrangian L_{k} that contains the effect of the delayed gravitational interaction. Since the propagation time of the gravitational interaction is very short compared to the orbital period one can extend the Lagrangian L of the centrally symmetric Kepler problem [

where summation over repeated Greek indices is implied. The Latin subscripts label discrete times. The single gravitational potential of the Kepler formulation is split into two potentials. The first potential describes a gravitational interaction that was radiated by the Planet in the pastat time t_{k}_{-2} and is sensed currently at time t_{k} by the Moon. The second potential describes a gravitational interaction that was radiated by the Moon in the past at time t_{k}_{-1} and is sensed currently at time t_{k} by the Planet. Thus the Lagrangian L_{k} is causal. As described by Dirac [

The Euler Lagrange [

The Euler Lagrange [_{µk} is a component of the position vector x_{k} of the Moon at time step t_{k} and M is the mass and y_{µk} is a component of the position vector y_{k} of the Planet at time step t_{k}. The time differences such as _{k}_{−2}, t_{k}_{−1}, t_{k}, t_{k}_{+1}, and t_{k}_{+2} are not necessarily consecutive. They are just time step labels. The time steps are not integer related. Bold letters such as u denote

vectors, single superior dots such as

To include the effect of both finite and infinitesimal time increments in the derivation of the equation of motion a sum S of Lagrangians L_{k} is used. The method used here is similar to the discrete Nagumo equation [

The equations of motion are obtained by inserting the sum of Lagrangians into the Euler Lagrange equations of motion for the Moon and the Planet.

By using the Lagrangians L_{k} of Equation (2.1) in the sum of Lagrangians in Equation (2.2) and substituting this sum into Equation (2.3) one obtains the following discrete Nagumo like equation of motion [

In Equation (2.4) the second terms are the Retarded forces and the third terms are the Recoil forces. By Newton’s principle of action and reaction the Recoil forces are equal in magnitude to the Advanced forces. Note that the second and third forceterms of Equation (2.4) have the same sign and are, therefore in the same direction. Observe that the true Advanced force F_{A} shown in pink in _{R}. Thus the third terms of Equation (2.4) are the Recoil force F_{Recoil}. Recall that the Recoil force F_{Recoil} is equal in magnitude to the Advanced force F_{A}. Thus these forces can be mathematically formulated now in terms of future coordinates. Reformulating Equation (2.4) in the more compact vector notation:

where bold font denotes vectors. The equations of motion contain one half of the Retarded and one half of the Recoil terms as described by Dirac [

The conventional transformation of variables used in the Kepler problem is as follows [

where u_{k} is only approximately the orbital coordinate vector and W_{k} is, only approximately, the center of mass coordinate vector. By inverting Equation (2.6) one obtains for the current Lunar and Planetary coordinate vectors:

The propagation time of the gravitational interaction between the objects is very short compared to the orbital period. Since the bodies move only small distances during the propagation time of the gravitational interaction the motion of the objects during this time can be approximated by the product of the current object velocity vectors

By substituting the transformation of variables of Equation (2.7) into Equation (2.8) one obtains the following approximation for the retarded and recoil vector differences:

For example, the difference in position vectors _{k} and t_{k}_{−1}, is approximated by the center of mass velocity vector

Lunar orbital velocity vector _{k}_{-1} that the Planet is sensing now, at the present, at time t_{k}.

Because of the form of the approximation of the delayed position differences of Equation (2.9) the time step describing subscripts became unnecessary. By substituting the transformation of variables of Equations (2.6), (2.8) and (2.9) into Equation (2.5) one obtains:

(2.10)

and

(2.11)

Since the effects of the delayed interactions are assumed to be small, Equations (2.10) and (2.11) can be expanded to second order in small parameters.

and

The first three terms of Equations (2.12) and (2.13) are the conventional terms of the Kepler problem. The justification for the expansion in small parameters is that the remaining terms of Equations (2.12) and (2.13) are multiplied by the ratios of the

Schwarzschild radii [

The radial equation of motion can be calculated by subtracting Equation (2.13) from Equation (2.12) and dot multiplying the resulting expression by

where _{ssR} and r_{ssT} are:

The first two terms of Equation (2.14) are the conventional Kepler terms and the remaining terms multiplied by the Schwarzschild radii are due to the delayed interaction.

The angular equation of motion is obtained by taking the cross product of the orbital radius u with the difference of Equation (2.13) minus Equation (2.12)

The orbital coordinate vector u can be expressed in the form of cylindrical coordinates. It is assumed that the center of mass motion is much slower than the orbital motion. Therefore, for the calculation of the orbital motion the center of mass velocity can be approximated by the almost constant velocity V of the reference frame.

By substituting Equation (2.17) into Equation (2.16) and multiplying by

where V is assumed to be a constant and uniform velocity approximately equal to the average velocity of the Earth in its Solar orbit. The “1” direction is taken to be in the direction of this Earth velocity. The Earth Lunar system center of mass moves with respect to this reference frame.

One can neglect the Schwarzschild radius of the reduced mass r_{ssR} compared to the orbital radius r in the first term and approximate the radius r in the last term of Equation (2.18) by the radial amplitude a_{A}. With these approximations, Equation (2.18) becomes an exact differential. The radial amplitude a_{A} is not the same as the semimajor axis a.

where _{ssR} and r_{ssT} to the orbital radius r is very small the orbital angular momentum density will differ only very little from the Kepler angular momentum density

Equation (2.19b) can be used to express the time derivatives of the orbital radius in terms of derivatives with respect to the angle θ to lowest order in small parameters. This is standard procedure in the solution of the Kepler problem.

In returning to the equation of motion of the orbital radius the first step is to substitute the transformation of variables of Equation (2.17) into Equation (2.14).

In order to calculate the values of the orbital radius as a function of the angle the time derivatives of r were formulated in terms of the derivatives with respect to the angle θ in Equation (2.20). This is common practice at this stage of the calculation. As stated before, since the center of mass motion is much slower than the orbital motion, it is assumed that for the duration of one orbit, the center of mass velocity remains constant. By substituting Equation (2.20) to lowest order into Equation (2.21) and multip-

lying the result by

The first three terms of Equation (2.22) are the familiar Kepler equation of motion. The remaining terms, which are multiplied by various Schwarzschild radii, are due to the delayed interaction. Assuming the following solution of this differential equation:

The first term of Equation (2.23a) is the solution of the Kepler problem. Here q is assumed to be a small dimensionless parameter. a_{A} is the orbital amplitude not the semimajor axis. By substituting Equation (2.23) to lowest order in small parameters into Equation (2.22) multiplying by the orbital amplitude a_{A} and collecting terms of equal orbital frequency one obtains:

where

and where Equations (2.19b) and (2.23b) were used in Equation (2.25b) to obtain Equation (2.25c).

Note that A_{1} in Equation (2.24) is the amplitude of a term oscillating at the resonant frequency of the orbital system. The orbital motion pumps the contribution of the motion due to the delayed gravitational interaction by periodically changing the delay time

amplitude A_{1} is proportional to the eccentricity ε. When the eccentricity is equal to zero there is no increase in the orbit. One can use the Laplace transform method to obtain the following solution of Equation (2.24):

Substituting Equation (2.26) into Equation (2.23a) and multiplying by a_{A} to obtain a solution for the orbital radius as a function of

An important result is that the fourth term on the right side with amplitude

Equation (2.27) continually increases with the angle θ. Since the angle θ increases monotonically with time, this term and the orbital radius r increase with time. This is one of the main results obtained in this article. It is the contribution to the increase of the orbital radius r due to the delayed gravitational interaction. The increase per orbit is small, it is of the order of the ratio of the Schwarzschild radius divided by the semimajor axis. For example, the Lunar orbit increases by 38 mm per Earth year [_{2} and A_{3} are small amplitudes of the second and third harmonic terms. Equation (2.27) can also be written as:

where

The precession angle is the angular change in the position of the major axis of the orbital ellipse. This can be calculated from Equation (2.29)

An important result shown in Equation (2.28) is that the second term in the square root depends on the square of the orbital angle. Since the orbital angle θ increases monotonically with time the effective eccentricity and the semimajor axis also increase with time. This effect is very small since the constants A_{0}, A_{1}, A_{2} and A_{3} are very small.

The constants A_{0}, A_{1}, A_{2} and A_{3} can readily be calculated from the knowledge of the masses of the objects and the average Earth velocity in its solar orbit. However, there are two more constants, the offset angle θ_{offset}, and the constant ε. The offset angle θ_{offset} is the present value of the angle θ. The fact that the angle θ_{offset} has a non zero value implies that the current expansion of the Lunar semimajor axis describable by an analytical model started a fixed time ago. For the Lunar orbit there is sufficient information in the form of the change of the semimajor axis per Earth year and the current values of the eccentricity from which these values can be calculated.

The calculations have to be performed numerically. The results of these calculations are given in the RESULTS section. Defining the current eccentricity

The amplitude A_{2} and A_{3} of the second and third harmonics are very small compared the eccentricity_{C} of the semimajor axis a is:

By expanding the semimajor axis of Equation (2.32b) in a Taylor series in θ_{offset} to lowest order one can calculate the current change

The numerical results of these calculations are given in the RESULTS section.

The energy lost by the orbital motion is transferred to the center of mass motion. This will cause the center of mass to accelerate. The acceleration of the center of mass can be

calculated by multiplying Equation (2.12) by

where Equation (2.15a) was used for the Schwarzschild radius r_{ssR}. The center of mass coordinates can be expressed in cylindrical coordinates.

Equation (2.34) can be expressed in cylindrical coordinates by substituting Equations (2.17a), (2.17b) and (2.35) into Equation (2.34).

The term multiplied by the Schwars child radius r_{ssR} is very small. One can assume that the center of mass velocity changes by a small quantity from its value V which it has in its orbit about the sun. Thus, inside the curly bracket of Equation (2.36) one can approximate the radial component

By substituting Equations (2.37) into the curly bracket of Equation (2.36) one obtains.

Substituting Equation (2.20) for the time derivatives of the orbital radius r in terms of the derivative of the orbital radius with respect to the angle θ to lowest order into Equation (2.38).

Substituting Equation (2.23a) to lowest order for the reciprocal radius

Since the orbital motion is much faster than the center of mass motion the average value over the orbital angle θ is used to calculate the average center of mass acceleration.

where

Another equation for the acceleration of the center of mass can be obtained by multiplying Equation (2.12) by

sulting expressions and cross multiplying the result by the center of mass coordinate vector W.

Reformulating Equation (2.42) in cylindrical coordinates by substituting Equations (2.17a), (2.17b) and (2.35) into Equation (2.42).

where Equation (2.15a) was used for the Schwarzschild radius r_{ssR}. By using the approximations of Equations (2.37) in the curly bracket of Equation (2.43) one obtains:

Substituting Equations (2.20) for the time derivative of the orbital radius r in terms of its derivative with respect to the angle θ to lowest order into Equation (2.44).

Substituting Equation (2.23) to lowest order for the reciprocal radius

Similar to Equation (2.40), since the orbital motion is much faster than the center of mass motion the average value over the orbital angle θ is taken.

Multiplying Equation (2.47) by

First using the approximations of Equations (2.37) in Equation (2.48). Then the resulting equation can be reformulated in the form of an exact differential.

where L is a constant of integration. Solving Equation (2.49b) for

By substituting Equation (2.50) for

where

tion (2.51) for the acceleration of the center of mass

There is sufficient data available to calculate the offset angle and the time period corresponding to the offset angle. The annual increase in the orbital radius of the Moon has been measured by NASA [_{0}, A_{1}, A_{2}, and A_{3}, etc. are listed in

Mass of Earth = 5.9736 × 1024 kg |
---|

Mass of Moon = 7.349 × 1022 kg |

Reduced mass = 7.25968795 × 1022 |

Current semimajor axis of Lunar orbit = 384,399,000 m |

Current eccentricity = 0.0549 |

Current change in semimajor axis per Earth year [ |

Current change in semimajor axis per Lunar orbit = 3.08260508 × 10^{−3} m |

Number of Lunar orbits per Earth year = 12.3272359096 |

The average orbital velocity of the Moon Earth center of mass used here as the center of mass velocity = 29,780 m per second |

Axis amplitude = 383,240,417.57 m |

Offset angle = 15,465,077.8171 rad. |

Offset time = 2,926,237.0636 years. |

Reduced mass Schwarzschild radius rssR = 8.08467935 × 10^{−5} m |
---|

Mass sum Schwarzschild radius rssT = 6.7342817 × 10^{−3} m |

A = 2.10955812 × 10^{−13} |

B = 1.48012788 × 10^{−8} |

A0 = 7.40085005 × 10^{−9} |

A1 = −4.06271941 × 10^{−10} |

A2 = −2.96025567 × 10^{−8} |

A3 = 4.06295104 × 10^{−10} |

Offset angle = 15,465,077.8171 rad. |

Offset time = 2,926,237.0636 years. |

vious analytical motion. The contribution of the delayed gravitational interaction to the Apsidal precession of the Lunar orbit is 83.83185072 µarc seconds.

A plot of the predicted contribution of the delayed gravitational interaction to the length of the semimajor axis of the Lunar orbit is shown in

The contribution of the delayed gravitational interaction to the eccentricity of the Lunar orbit is shown in

The loss of the orbital energy is transferred to the center of mass motion. This will cause the center of mass to accelerate. A plot of the center of mass acceleration is shown in ^{−16} m per second squared.

Another interesting system that can readily be analyzed is the Brown Dwarf Binary system 569Bab. Lane [^{17} m. from us. The radius of the orbit of the Brown Dwarf pair 569B about the star 569A as seen from Earth is about 5” or 49 AU or 7.330295635 × 10^{12} m. The pair 569B orbits about the star 569A in 15 years. The Brown Dwarf system 569Ba and 569Bb has a combined mass of 0.123 solar masses and a mass ratio of 0.89. The Brown Dwarfs orbit about each other in ^{8} years. The data from the literature for the calculation of the motion of the Brown Dwarf star pair 569Bab is listed in _{0}, A_{1}, A_{2}, and A_{3}, etc. are listed in

There is not sufficient data to accurately calculate the analytically calculable start of the expansion of the semimajor axis. The earliest time of the analytically calculable start of the expansion of the semimajor axis is 8.9271548613 Million years ago. This is a maximum value. It could have started at a later time. Perhaps one of the brown dwarf stars collided with a large enough object 8.9271548613 Million years ago or later to alter its orbit and obscure its previous analytical motion.

A plot of the predicted contribution of the delayed gravitational interaction to the length of the semimajor axis of the orbit of the 569Bab system is shown in

Mass of 569Ba = 1.296197162 × 1029 kg |
---|

Mass 569Bb = 1.153615474 × 1029 kg |

Reduced mass = 6.10378558 × 1028 kg |

Semimajor axis = 1.34638083 × 1011 ± 2.9919574 × 109 m. |

Axis amplitude = 1.20851143 × 1011 m |

Eccentricity = 0.32 ± 0.02 |

Orbital period = 892 ± 25 days |

Estimated age of system = 3 × 108 years. |

The average orbital velocity of the center of mass of the 569Bab pair about the central star 569A is 97,290.506 m per second. |

Reduced mass Schwarzschild radius rssR = 67.974201624 m |
---|

Mass sum Schwarzschild radius rssT = 272.82095014 m |

A = 5.62462214 × 10^{−10} |

B = 1.57974235 × 10^{−7} |

A0 = 7.95207815 × 10^{−8} |

A1 = −2.49159017 × 10^{−8} |

A2 = −3.15862075 × 10^{−7} |

A3 = 2.52758775 × 10^{−8} |

Offset angle = 25,686,407.307 rad. |

Offset time = 8,927,154.8613 years. |

started as early as 8.927154154 Million years ago or at a shorter time. Perhaps at that time an object collided with one of the two Brown Dwarf stars that effect the orbit enough to obscure its previous analytical describable motion.

The contribution of the delayed gravitational interaction to the eccentricity of the orbit of the 569Bab Brown Dwarf stars is shown in

The loss of the orbital energy is transferred to the center of mass motion. This will cause the center of mass to accelerate. A plot of the center of mass acceleration is shown in ^{−14} m per second squared.

Again, it is assumed that the radius of the orbit of the pair about the star 569A is large compared to the orbit of the Brown Dwarfs about each other. Thus, this orbital velocity is assumed to be the approximate constant center of mass velocity of the Brown Dwarfs.

The small effect of the propagation delay of the gravitational interaction on the motion of the Earth Moon and the Brown Dwarf 569Bab binary star systems were calculated. The calculated values are in very good agreement with observed values.

Recent measurements have shown that gravitational waves and thus the gravitational interactions propagate with the speed of light. The gravitational propagation delay exists whether the interaction is modeled by the deformation of the four dimensional space due to the mass of the bodies, or it is modeled by a gravitational interaction that is propagating between objects. In each case a change in position of one object takes time to be sensed by the other object.

The delayed interactions between two objects are causal. The single interaction force of the model that considers interactions to be instantaneous is split into two forces in a model that takes the propagation delay of the interaction in consideration. Object ONE senses currently a force radiated by object TWO in the past, see

The propagation delay of the gravitational interaction couples the orbital and center of mass coordinates of orbiting systems. The propagation delay between objects varies periodically for systems with eccentric orbits. The periodically changing propagation delay pumps the motion of the objects. This causes both the eccentricity and orbits to grow and loose energy. The loss in orbital energy is transferred to the center of mass motions. Thus, the center of mass accelerates. These effects are very small. The semimajor axis of the Lunar orbit grows by 38 mm per Sidereal year and the center of mass acceleration is a fraction of a pico meter per second squared.

By using the present astronomical data one obtains that the growth of the orbital axis and eccentricity started at a time shorter than the age of the systems. This can, perhaps, be explained by one of the system components having had a collision that erased the previous analytically describable motion.

All orbiting systems in the universe convert some of their orbital energy to its center of mass motion. The center of mass acceleration of the various orbiting systems is in random directions. One can consider the very large number of star systems, galaxies, and galactic clusters as molecules in the universe. The transfer of internal orbital energy to the molecular motion will increase the entropy, temperature and pressure of the gas. The gas will expand. Alternatively, one should include the change in orbital energy with the energy and mass of the Universe in the calculation of the accelerating expansion of the Universe.

It is not known if this contribution is enough to explain the present accelerating expansion of the Universe [

I thank my wife Marlene Danzig Kornreich for her suggestions to the text and making the text more understandable to a reader.

Kornreich, P. (2016) The Contribution of the Gravitational Propagation Delay to Orbital and Center of Mass Motions. Journal of Modern Physics, 7, 1909-1932. http://dx.doi.org/10.4236/jmp.2016.714169