Stranger-Thanks,
I followed some of what you said. I have a question:
what are “chaotic momentum exchange events”?
And assuming that is a method of one body capturing another, why doesn’t it work for systems like Earth/Moon?
It’s not at all rare for stars to form in binaries with comparable masses. Why couldn’t the same dynamic processes occur for a pair of planets?
Chaotic momentum exchange occurs in areas of gravitational equipotential (such as libration points) such that small bodies can transfer momentum to each other and become strongly coupled to each other, especially by transferring mometum to and from other nearby bodies, e.g. the Galilean moons of Jupiter. The Earth and Moon of such different mass, and are not both strongly under the influence of another nearby body that this is not really plausible to explain their tight coupling. As separate bodies on differing trajectories, the Earth and Moon should fly past each other and never transfer enough momentum to couple together. The original Theia hypothesis was a glancing blow that caused the two bodies to become coupled, but even that doesn’t hold water, and the most recent hypothesis was a direct impact which ejected enough material to coalease into two or more bodies which eventually combined to make the Moon.
Because stellar clouds condense in ways formed in part by wavefronts in the stellar medium and eventually come to form out of areas of common rotational momentum, but planets form in a protoplanetary disk that is already defined by the central mass, and either tend to combine with or eject other mass. We don’t see any large masses (of Lunar size or greater) that have formed couplets, and the model simulation that has been done places an upper limit on the mass of bodies that this is likely for that is much smaller than spherical planet-forming bodies.
However, this is all based upon models which rely on assumptions wbich rely heavily on the observations we have the technology to make, e.g. our own system, and a narrow set of exoplanets that can be observed. And observations are finding all sorts of planetary configurations that are not explainable with existing models, albeit more in the gas giant range of planets that we can easily observe. We may find that larger mass couplets are possible or even common and will require radically new models of planetary formation.
Stranger