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I recently heard from a couple astronomy graduate students that Sundman solved the entire three-body problem of Newtonian gravity over a century ago, for generic initial conditions with non-vanishing angular momentum. This sounds almost too good to be true!

They said the general solution was either a series in powers of $t^{1/3}$ or powers of $\frac{e^{\alpha t^{1/3}} - 1}{e^{\alpha t^{1/3}} + 1}$ for some appropriate $\alpha$, the former related to binary collisions and the latter related to a conformal mapping.

I have briefly searched for discussions of these results of Sundman, but I haven't seen explicit forms for the series and I'm left unsure whether his proof of a series was constructive. My sense is perhaps that the transformations above can be used to argue that such an analytic solution exists but does not give the solution explicitly or a way to find the solution explicitly. However, on e.g. Wikipedia, it's stated that one would need to include truly massive numbers of terms for the series to be of practical value, which makes it sound that the series is explicitly known or can be constructed.


My question is: is Sundman's solution to the three-body problem constructive? If so, what is the series solution in terms of the nine initial positions and nine initial velocities of the bodies? For example, an explicit, iterative way of computing the coefficients in the series would suffice.

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    $\begingroup$ @FlatterMann I'm happy even if it converges too slowly to be practical, but I'm hoping to see the explicit form of the series. $\endgroup$
    – user196574
    Commented Sep 29, 2022 at 22:05
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    $\begingroup$ Ask this also on math sites, I think there is a higher chance of good answers there. $\endgroup$ Commented Sep 29, 2022 at 22:27
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    $\begingroup$ See here for an analysis by Belorizky, who seems to be interested in computing the first terms in the series (manuscript also in French), to be found in the last few pages of Sundman, chapter XI, p. 174-179. $\endgroup$ Commented Sep 29, 2022 at 22:54
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    $\begingroup$ The original treatise on the 3-body problem here. It is in French so it may not be accessible to everyone. I'm not a french speaker myself, so I don't really understand what the series in the last few pages represents. $\endgroup$ Commented Sep 29, 2022 at 22:55
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    $\begingroup$ Go to page 140 of the original paper linked by @DinosaurEgg. This is the "written-out" version of the series solution you (I) seek (sought). $\endgroup$ Commented Dec 5, 2022 at 0:03

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Try this: "Exposition of SUNDMAN'S regularization of the three-body problem" Donald K. Yeomans link https://ntrs.nasa.gov/citations/19670005590

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  • $\begingroup$ Sadly the link doesn't work for me. Perhaps you could give a little summary of the paper, or point out important points made in it. $\endgroup$ Commented Dec 29, 2023 at 6:31

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