J-M Souriau: On the dynamics of the solar system (p3)
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The surface of the sun is lifted: there are therefore tidal effects, therefore dissipative processes, whose result is the wearing down of orbits, the fact that planetary trajectories, even perfectly circularized (by tidal effects), could be spirals, which would tend to make them converge toward the sun and merge with it, even though the characteristic time of this phenomenon is considerable (not quantified so far).
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On the other hand, I believe there are sets that obey the golden rule and no longer exchange energy with the celestial body around which they orbit. These are the asteroid belt and the rings of the large planets (Saturn, Uranus, essentially). These rings do not create tidal effects in the central body (however, Saturn's rings are indirectly influenced by the planet through the action exerted on them by certain satellites). The elements of Saturn's rings are ice blocks, with "own movements" relative to each other, almost zero. If these own movements were significant, they could not occur only in two dimensions. Therefore, Saturn's ring would be thick. Moreover, collisions between blocks would shower us with comets, making Earth uninhabitable.
Catastrophic parenthesis.
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We do not exactly know the size of the ice blocks composing the rings, but some could be twenty kilometers. A block of this size, equivalent to a mountain, crashing into the Earth's atmosphere at dozens of kilometers per second would create a shock wave that would go around the Earth, long before the block had begun to melt.
Fig.11: Penetration of a comet into the Earth's atmosphere.
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Upon hitting the Earth's surface, it explodes into fragments. Millions of tons of earth or rock are also turned into fine dust. The incident shock wave reflects. It leaves behind a bubble of hot, high-temperature air. The incident shock wave propagates laterally, centrifugally, destroying everything in its path. But the important thing is the "delay effect." This hot air, lighter, will rise, carrying millions of tons of dust particles, as small as a micro, which can then remain one or two years in the stratosphere (simply because their falling speed is very low). This dusty cover will block solar radiation.
Fig.12: Cometary night.
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First dispersed in longitude, then in latitude, due to the drop in temperature and the stop of photosynthesis, this shield will cause the death of a large proportion of living beings, whether animals or plants.
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Our planet and the comet impact object, of varying importance. At the beginning of the century, it was indeed a comet that fell in Siberia, in Tunguska. Testimonies: light, thunder-like noise. On site: no exotic debris. But the trees had been knocked down, like this:
Fig.13 (p019): The trees, at the Tunguska site.
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The fact that the trees remained upright in the center is typical of the impact, not of an object, but of the action on the ground of a shock wave preceding an object already broken into thousands of fragments.
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A similar phenomenon occurred in Hiroshima, where what caused damage on the ground were not fragments, but a shock wave. Thus, a building located exactly at the impact point, which received the wave vertically, remained upright, while the buildings immediately adjacent were knocked down.
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At the Tunguska site, the larch trees located exactly at the impact point, if they had remained upright, would have been completely "stripped" as they passed.
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When talking about comets, the word "dirty snow" is sometimes evoked. Indeed, there is no reason to think that this frozen, crystallized water could have formed hard ice, as would be the case if it were subjected to pressure forces. In a small comet, cohesive and gravitational forces are very weak. Thus, what would arrive on Earth could be... a snowball, the size of a mountain, moving at a speed of several tens of kilometers per second. This would not prevent a very intense shock wave from forming, synonymous with strong heating of the air, in the incident phase and especially after reflection, when all the kinetic energy is transformed into heat. The object itself has no consistency, but what is harmful is its energy, synonymous with overpressure and thermal shock. When attacking the dense atmosphere, it creates its shock wave. If the impact with the air is violent enough, the contact of the comet with the atmosphere is equivalent to an explosion. After the damage caused by this shock wave at Tunguska, what followed could perhaps be compared to a hailstorm.
End of this catastrophic parenthesis
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The rings of Saturn seem to be an example of "completely relaxed" subsystems.
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On the other hand, the Neptune-Pluto subsystem, very resonant (period ratio very close to 3/2), is a dissipative structure.
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The solar system is therefore a composite system, with "relaxed" subsets and others, not. The resonant subsystems then have their own stability, comparable to that of Bénard vortices or Von Karmann vortex streets.
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Personally, I think the solar system would tend toward a state of maximum relaxation, where all elements would obey golden laws, global (planets) or local (Saturn's and Jupiter's satellites). And Souriau adds that this conjecture would need to be confirmed by numerical simulations, which we are going to undertake.
Here comes an idea from my wife Claire, who has long been fascinated by the solar system problem, and who says:
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If we find in the solar system relaxed subsets, obeying a golden law, and others resonant, comparable to dissipative subsystems, it is because an unknown perturbation has occurred, otherwise the solar system would be in a quasi-relaxed state with not so many anomalies, such as:
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The presence of Earth on a "less resonant" orbit
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The existence of an asteroid belt between Mars and Jupiter
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The relatively high eccentricity of Mercury's orbit
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The almost complete absence of rings around Jupiter, while Saturn and Uranus have them
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The existence of a metallic core in the Earth and of strong tectonic activity
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The inclinations of Pluto's orbit (18°) and of Uranus' rotation axis (close to 90°)
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The large deviations of some of Saturn's and Jupiter's satellites from a golden law
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The solar system could therefore have previously experienced a more "calm" situation, which was disturbed by an important event. More precisely, Claire thinks that the perturbation occurred in the young solar system, during its formation, when the stars were "in the process of calming down" (tendency towards circularization of their orbits, creation of the plane of the ecliptic) and that some elements have retained the scars...