Here's a proposed answer to the question "Why is Earth moving away from the Sun?" It uses a modified idea of gravity where gravitational waves are absorbed by the Sun then re-radiated as a push that moves Earth away at 1.5 cms (or as I've read elsewhere, 15 cms) per year. Currently, solar-system formation can be summarized thus -
“Dust grains assemble by chemical bonding. Once they are sand or gravel sized, how they continue to stick is a mystery. Metre-sized rocks should spiral into the star rapidly due to disk drag. Once rocks somehow get past these barriers, they collide with each other in in a chaotic and random way assembling the planets.” (Australian National University’s online astrophysics course “Greatest Unsolved Mysteries of the Universe” [presented on edX by Prof. Brian Schmidt and Dr. Paul Francis], 2012-2019, ANUx - ANU-ASTRO1x: Lesson 8 [Solar System Formation])
The following method of building planets is preferred to collisions between rocks and dust in the disk because most planetary systems seem to outweigh the protoplanetary disks in which they formed, leaving astronomers to re-evaluate planet-formation theories. (AstroNews: Astronomy, February 2019, p. 17)
Visualize a parallelogram with the bottom left-hand angle denoted by A and angles B, C, D are marked counterclockwise. Two vectors acting on a point may be represented by two adjoining sides of a parallelogram, so that their resultant is represented in magnitude and direction by the diagonal of the parallelogram (AD and CD, for example, can symbolize the electromagnetic and gravitational vectors … while the resultant diagonal of DB substitutes for the interaction of those two forces).
Two sides thus illustrate the graviton's spin 2 and the photon's spin 1. The resultant diagonal represents the interaction of the sides/vectors (1÷2 = the spin ½ of every matter particle). The mass produced during the photon-graviton interaction (the energy and momentum of photons and presently hypothetical gravitons produces a pressure we call mass) could therefore produce any particle you can think of.
When humans really are flying around the universe in Star-Trek-like starships, tractor beams will be handy things. The first step in building one requires us to look about 100 years into the past, when Einstein developed his theory of General Relativity. General Relativity says gravity is a PUSH caused by the curvature of space-time, and has updated the old Newtonian definition of gravity as a PULL.
Since mass (and the nuclear forces associated with matter) are a product of gravitation, the gravitational waves do not simply penetrate matter but - like a biological enzyme - must pause to react with it. The matter absorbs and re-radiates the gravitational waves so rapidly that they appear to merely pass through the matter unimpeded. The GEM wave itself doesn’t attract an object to the starship. The matter formed at the wave-packet front by the GEM (Gravitational-ElectroMagnetic) wave ... or Tractor Beam ... re-emits waves, pushing the object in the tractor beam (between the starship and the wave-packet front) towards the starship. This is similar to a push that moves Earth away from the Sun.
Since mass (and the nuclear forces associated with matter) are a product of gravitation, the gravity-to-mass reaction can then be reversed, eliminating the conspicuous mass and replacing it with an ordinary gravitational wave.