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tl;dr: Consider the birthday paradox. In astronomy we call these resonances. Sometimes, two seemingly unrelated periodic events will occur together, synchroniz
by t8sr 3y ago
tl;dr: Consider the birthday paradox.
In astronomy we call these resonances. Sometimes, two seemingly unrelated periodic events will occur together, synchronized by a ratio between some small integers.
I think the most typical example is the one they teach you in the first Solar System 101 class to wow you (it works): the 3:2 resonance between the orbits of Pluto and Neptune.
Sometimes it might turn out to be a coincidence with more accurate measurements, or when you find evidence that this moment in time might be somehow unusual.
For example, Earth and Venus also seem to be in 8:13 orbital resonance, but, in fact probably aren't. On closer inspection, it turns out that there is error of about 0.4% after 8 years and it compounds. It takes a while to compound, but effectively you can't use this "near resonance" to predict where the two will be in their orbits in a few thousand years.
In fact, with enough bodies in the solar system and the birthday paradox, there are many compelling candidate resonances with small integer ratios, but the majority of them are probably just random coincidences.
- t8sr 3y agoJust to clarify the difference between "true" resonance and a coincidence: True resonance reinforces itself. For example, Pluto speeds up and slows down in its orbit as it passes Neptune and the exchange of energy between the two works out such that the lowest energy state is a 2:3 resonance, so that's where they would end up even if you "poked" the system a little. A coincidence is not self-reinforcing. If you "poked" the system, it would disrupt the ratio and it'd stay disrupted. Sometimes, the preconditions for resonance might disappear, and then you end up with a coincidence at a nearly perfect ratio that slowly drifts afterwards. The opposite also happens.
- jgalt212 3y ago> A coincidence is not self-reinforcing. If you "poked" the system, it would disrupt the ratio and it'd stay disrupted. What would happen if you poked at object at one of the Lagrange points? e.g. the James Webb Space Telescope.
- fhdkweig 3y agoOf the 5 Lagrange points, 2 are stable. If you poke an object at one of the 2 stable points, the object begins to orbit in a circle around that invisible point.
- sp332 3y agoMost Lagrange points are unstable. Only L4 and L5 are stable. https://en.m.wikipedia.org/wiki/Lagrange_point#/media/File%3ALagrange_points2.svg https://en.m.wikipedia.org/wiki/Lagrange_point#/media/File%3...
- sandworm101 3y agoBut it is also possible, perhaps likely, that some coincidences are in fact higher-level resonances between groups of planets. These would be multi-body problems that may take thousand or millions of years to react to perturbations. The calculations for these may well be beyond our current capabilities to detect (3+ body problems).
- deleted 3y ago[deleted]
- dr_dshiv 3y agoHypothesis: near orbital resonances are more stable than perfect resonances.
- t8sr 3y agoI mean… no? That makes no sense. You can’t just say “hypothesis: something random”, that’s not how anything works. :)
- dr_dshiv 3y agoFirst of all— says who? Second of all, it’s not random. In music, near resonances are more consonant than perfect resonances. And, orbital resonances tend to disrupt stability (eg, if earth and Venus were in an orbital resonance, then they would often pull at mercury really hard, potentially pulling it out of orbit). Previously, I opted not to give my rationale for the hypothesis in case someone had any reason to refute it.
- t8sr 3y agoHow would anyone even refute a vague statement like that? Secondly, the word "consonant" has many different definitions, so again, your statement could mean almost anything. The concept of consonance has no obvious connection to whether or not a system is stable. "Orbital resonances tend to disrupt stability" - that's not true, especially not the thing about Mercury. The influence of the pair on each other would be great, and either cause the resonance to fall apart or, more rarely, to lock in. But mercury's orbital period is not in a simple ratio with the resonant pair, so nothing would be meaningfully different. Look, I can tell from your profile that you're a professor in some kind of social science. Is it possible that you're, like many people in academia, under the influence of a cognitive bias that makes you think your expertise in one field should somehow transfer into insights in a completely different field? And, again, showing up and just saying "hypothesis: whatever" is something people can either ignore or engage with, but if you really wanted to engage, you would try to say something concrete instead of just making yourself look clever.
- dabluecaboose 3y agoAnother good example is when you're listening to music in the car and think your turn signal is perfectly in time with the song, only to have it slowly drift off once you notice.
- derefr 3y agoI can see how orbital mechanics would lead to these sorts of small-integer ratios being true for arbitrary periods and then disappearing, yet this fact still seems unintuitive/unsatisfying somehow. I think it's because we're so all familiar with quantum electrodynamics now, that it actually seems somewhat counterintuitive that the (stable) orbits of planets aren't quantized valence shells!
- deleted 3y ago[deleted]