slowly drifting off

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { background-color: #2F243A; margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    // Feel free to change or delete any of the code you see in this editor!
    var tot_points = 3500,
        sub_points = 1420,
        width = 960,
        height = 500,
        svg = d3.select("body").append("svg")
          .attr("width", width)
          .attr("height", height),
        data = [];

var nodes = d3.range(tot_points).map(function(d, i) {
  return {
    r: Math.random() * 5,
    color: i < sub_points ? '#FDECEF' : '#9D6381'
  }
})

var simulation = d3.forceSimulation(nodes)
    .velocityDecay(0.22)
    .force("x", d3.forceX().strength(0.02))
    .force("y", d3.forceY().strength(0.02))
    .force("collide", d3.forceCollide().radius(function(d) { return d.r + 1; }).iterations(2))
		.force('center', d3.forceCenter(width / 2, height / 2))
    .on("tick", ticked);

function ticked() {
  var u = svg
    .selectAll('circle')
    .data(nodes)

u.enter()
    .append('circle')
    .attr('r', function(d) {
      return d.r
    })
    .merge(u)
    .attr('cx', function(d) {return d.x})
    .attr('cy', function(d) {return d.y})
  	.style('fill', function(d) {return d.color})

u.exit().remove()
}

</script>
</body>

https://d3js.org/d3.v4.min.js