Live data from Hacker News

Show HN: Browser-based interactive 3D Three-Body problem simulator

trisolarchaos.com

21–30 of 119 posts

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#21
> Open to suggestions for additional presets or features!

Anaglyphic (red/cyan) 3D rendering would be nice. I've created a lot of anaglyphic 3D apps over the years, but they're no longer very popular -- I suspect it's the goofy glasses one must acquire and wear.

But a true 3D view of an orbital simulator like this greatly increases its impact and tutorial value.

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#22

No physics expert but isn't this unpredictable (based on what I saw in series) ? Amd this does seem predictable, I saw this for almost a minute

> No physics expert but isn't this unpredictable (based on what I saw in series) ?

A three-body orbital problem is an example of a chaotic system, meaning a system extraordinarily sensitive to initial conditions. So no, not unpredictable in the classical sense, because you can always get the same result for the same initial conditions, but it's a system very sensitive to initial settings.

> Amd this does seem predictable, I saw this for almost a minute

The fact that it remains calculable indefinitely isn't evidence that it's predictable in advance -- consider the solar system, which technically is also a chaotic system (as is any orbital system with more than two bodies).

For example, when we spot a new asteroid, we can make calculations about its future path, but those are just estimates of future behavior. Such estimates have a time horizon, after which we can no longer offer reliable assurances about its future path.

You mentioned the TV series. The story is pretty realistic about what a civilization would face if trapped in a three-solar-body system, because the system would have a time horizon past which predictions would become less and less reliable.

I especially like the Three Body Problem series because, unlike most sci-fi, it includes accurate science -- at least in places.

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#23
post #10

Is this with Gemini 3?

> Is this with Gemini 3?

An LLM couldn't provide results for a sim like this, compared to a relatively simple numerical differential equation solver, which is how this sim works. Unless you're asking whether a sim like this could be vibe-coded, if so, the answer is yes, certainly, because the required code is relatively easy to create and test.

Apart from a handful of specific solutions, there are no general closed-form solutions for orbital problem in this class, so an LLM wouldn't be able to provide one.

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#25
post #19
post #16

I spent a long time playing with the sim. Nice work. Most of the random data sets that I ran ended up with a two body system, where the third body was flung far into space never to return. However, some of these were misleading. I had one running for 15 minutes at 5x, and the third body did eventually return.

It might be fun to add some kind of visualization showing when a body has enough energy to potentially escape the system.

Question, can you mathmatically plot a trajectory across time X and energy required to see when it's met and how long it would take given a start position or something? Or is the simulation so complex that you can never project. Oh never mind I see answers to this elsewhere here, cheers.

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#27
post #16

I spent a long time playing with the sim. Nice work. Most of the random data sets that I ran ended up with a two body system, where the third body was flung far into space never to return. However, some of these were misleading. I had one running for 15 minutes at 5x, and the third body did eventually return.

> However, some of these were misleading. I had one running for 15 minutes at 5x, and the third body did eventually return.

That's not misleading. Real three-body orbital systems show this same behavior. Consider that such a system must obey energy conservation, so only a few extreme edge cases lose one of its members permanently (not impossible, just unlikely).

Ironically, because computer simulators are based on numerical DE solvers, they sometimes show outcomes that a real orbital system wouldn't/couldn't.

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#29
post #15

No physics expert but isn't this unpredictable (based on what I saw in series) ? Amd this does seem predictable, I saw this for almost a minute

The link points to one of the stable solutions, and there are actually quite a few of those. The problem is that there’s no general closed form that tells us exactly where the bodies will be in the future, so we rely on numerical methods to approximate the motion. If you hit Reset All a few times or add more bodies, you’ll start to see the chaos

When you say 'stable' here, do you mean 'periodic' or are these solutions actually stable in the face of small perturbations (as opposed to the sensitive dependence on initial conditions that we'd expect from a chaotic system)?

Re: Show HN: Browser-based interactive 3D Three-Body problem simulator

#30
Tried writing an electrostatic particle simulator in Turbo Pascal 7 with BGI as a teen, a handful of particles before it crawled. Then saw a galaxy collision sim on a CD-ROM magazine disc handling thousands of bodies smoothly. Thought it was assembly tricks.. now I'm sure it's algorithmic (avoiding N**2 runtime) but never dug into the specifics. Are charges vs gravity sims essentially the same n-body problem?
Post reply on HN