When to use N-Body Sandbox 3D Explorer
Open the N-Body Sandbox 3D Explorer when you want to place the bodies yourself and watch what gravity does with them - orbits that hold, near-misses that fling a body away, and captures you did not plan. Choose a different page when you need one fixed, repeatable figure or a static diagram of a single well.
Good reasons to open the N-Body Sandbox
The N-Body Sandbox 3D Explorer earns its place when the lesson is the behaviour, not a single tidy answer.
- Classroom demos of emergent orbits, scatters, and captures
- Showing that chaos grows as bodies are added, which is a real property of these systems rather than a defect
- Introducing the real Newtonian constant G alongside a system the reader built
Skip the N-Body Sandbox when the goal is a fixed choreography to point at, or a still picture of one gravity well. The two sibling explorers below do those jobs directly.
Setting up a system in the N-Body Sandbox
The N-Body Sandbox 3D Explorer opens on a starter system of four bodies: one heavy central mass and three lighter ones already in motion. From there the sequence is short.
- Open the N-Body Sandbox 3D Explorer and let the starter four-body system settle into its motion.
- Read the facts panel: the real G value, how many bodies are in the scene out of the 16 the sandbox allows, how many are on bound orbits, and how many are escaping or scattering.
- Pick Light body or Heavy body for whatever you add next. The panel confirms the choice on its next-body row.
- Click the ground to drop that body in. Each new body arrives with a small randomised velocity, so it starts on a trajectory instead of falling straight into the middle.
- Drag to orbit the camera and scroll or pinch to zoom while the fading trails show where each body has been. Pause holds the scene for a screenshot; Reset returns to the original four.
Adding a heavy body next to an existing orbit is the quickest way to break a stable pattern on purpose - the bound count in the facts panel drops as soon as one of the lighter bodies picks up enough energy to leave.
N-Body Sandbox compared with the two sibling explorers
| Option | Strength | Access | Trade-off |
|---|---|---|---|
| N-Body Sandbox 3D (this guide) | Free-form gravity you set up yourself | Free, in browser | Scaled constant on screen, up to 16 bodies |
| Three-Body Problem 3D | The fixed classic figure-8 choreography | Free web | Not a general N-body sandbox |
| Gravity Well 3D | Static potential-well surfaces | Free web | Not a live multi-body simulation |
N-body sandbox key figures
| Quantity | Value |
|---|---|
| Newtonian gravitation | F = G m1 m2 / r^2 |
| Gravitational constant (G) | 6.67430 x 10^-11 m^3 kg^-1 s^-2 (CODATA 2022) |
| Bodies allowed in one scene | 16 |
Limits worth knowing before teaching from it
On-screen motion in the N-Body Sandbox 3D Explorer runs on a scaled gravitational constant so the dynamics stay visible inside one screen; the real CODATA value in the table is shown for literacy, not used to move the spheres. Close-range force is softened, which is standard practice in N-body code and stops the force blowing up when two bodies pass very near each other. The result is an educational sandbox rather than a general-purpose ephemeris, so treat the positions as illustrative.
Open the N-Body Sandbox 3D Explorer to build a system, or step across to Three-Body Problem 3D and Gravity Well 3D for the fixed-figure and static-well views.
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