
Periodic Planar Three-Body Orbits - jashkenas
https://observablehq.com/@rreusser/periodic-planar-three-body-orbits
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NotSammyHagar
I searched around for observablehq. I hadn't see it before. Checkout
[https://observablehq.com/@observablehq/five-minute-
introduct...](https://observablehq.com/@observablehq/five-minute-introduction)
and
[https://news.ycombinator.com/item?id=20184181](https://news.ycombinator.com/item?id=20184181).

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raverbashing
I wonder how many of those would be feasible in real life situations

For example, a celestial body coming in proximity to another will impart tidal
forces, might involve some kind of mass exchange or simply find form of
atmospheric drag.

~~~
p1mrx
The three-body problem has very few _stable_ solutions, which include an
equilateral triangle and a figure eight:

[https://sites.math.washington.edu/~morrow/336_12/papers/adri...](https://sites.math.washington.edu/~morrow/336_12/papers/adrian.pdf)

"The actual probability of finding such a [figure eight] star system is
somewhere between one per galaxy and one per universe."

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garmaine
This is an extremely misleading statement. The Earth-Sun-Moon is a 3 body
system and quite stable. Obviously moons and multi-planet systems are quite
common. As are 3-star systems. Our nearest neighbor is one: Proxima/Alpha
Centauri. And Proxima Centauri has a planet too.

What is difficult to find stable solutions for is 3 body movements where the
three objects are of similar mass. But that is an improbable circumstance to
start with.

Also that citation seems to be totally disregarding the fact that multi-body
systems never start in stable systems but instead naturally align into them.

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Myrmornis
If I work on an observable notebook, is it (or can it be) backed by a git
repo? Is it convenient to edit the code in a traditional text editor?

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jashkenas
Not too easily, and no.

With Observable notebooks we're trying to expand the boundaries of how live,
networked and interactive a notebook can be. So, to that end, the notebook
_is_ the editor, visualizations update reactively with your changes to the
code just as they would update to changes in the data, you can inspect and
autocomplete actual values flowing through your program, and you can fork
someone else's notebook or merge their changes with a single click.

There's built-in history too (live, every version reproducible), as seen in 15
seconds with an animated gif here:
[https://observablehq.com/@observablehq/history](https://observablehq.com/@observablehq/history)

In the future, we're thinking about working on APIs for better git and generic
text editor integration; but for the reasons listed above, the primary focus
for now is on making working directly in a notebook on the web the best
experience possible.

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Myrmornis
Thanks! I have another question about observable: are you aware of anyone
using mathbox in conjunction with observable? Do you think that could be a
fruitful direction?

[https://github.com/unconed/mathbox](https://github.com/unconed/mathbox)

~~~
jashkenas
I'm not aware of anyone using Mathbox in Observable, although it certainly
seems promising!

On the other hand, I have seen quite a lot of neat Ganja.js notebooks float
by, for plotting explorations of algebraic spaces in notebooks:
[https://observablehq.com/search?query=ganja](https://observablehq.com/search?query=ganja)

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317070
But do these 'analytically' orbit? I reckon such a proof must be quite
intricate? Are there proofs for each of those families?

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6gvONxR4sf7o
I googled the name of the first set of orbits and found this
[https://arxiv.org/pdf/1303.0181.pdf](https://arxiv.org/pdf/1303.0181.pdf)

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JadeNB
Routine plea: please link to abstracts (Šuvakov and Dmitrašinović - Three
classes of Newtonian three-body planar periodic orbits -
[https://arxiv.org/abs/1303.0181](https://arxiv.org/abs/1303.0181)) rather
than directly to PDFs. (It is an easy click to get from abstract to PDF, but
not _vice versa_.)

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rreusser
That's good advice. Thanks! I've switched a couple of the links to abstracts
instead of PDFs, though what I really need is a proper references section
since direct links are also convenient—if they work.

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baliex
They're interesting, hypnotic, and beautiful!

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j16sdiz
This notebook sharing website look nice. Why we haven't seen this before?

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dang
Previous submissions may be of interest:
[https://news.ycombinator.com/from?site=observablehq.com](https://news.ycombinator.com/from?site=observablehq.com)

