N-Body Problem

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  background: #333;
}

</style>
<canvas width="960" height="500"></canvas>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var canvas = document.querySelector("canvas"),
    context = canvas.getContext("2d"),
    width = canvas.width,
    height = canvas.height;

var n = 200,
    tau = 2 * Math.PI,
    nodes = d3.range(n).map(function() { return {radius: Math.random() * 8 + 2}; });

var force = d3.layout.force()
    .charge(0.5)
    .gravity(0)
    .friction(1)
    .nodes(nodes)
    .size([width, height])
    .start();

context.fillStyle = "#fff";

force.on("tick", function(e) {
  context.clearRect(0, 0, width, height);

var q = d3.geom.quadtree(nodes), node, i;
  for (i = 1; i < n; ++i) q.visit(collide(nodes[i]));

for (i = 1; i < n; ++i) {
    node = nodes[i];
    context.beginPath();
    context.arc(node.x, node.y, node.radius, 0, tau);
    context.fill();
  }

force.resume();
});

</script>

https://d3js.org/d3.v3.min.js