ction = i / numKeyframes;
        var t = (fraction * 0.6) + 0.1;
        keyframes.push({opacity: t});
      }
      return keyframes;
    }
    function startExperiment()
    {
      var keyframes = makeKeyframes();
      for (var i = 0; i < N; i++) {
        var elem = document.createElement("div");
        elem.style.backgroundColor = randomColorGenerator();
        elem.style.transform = "rotateZ(" + ((i + 1) * 10.1).toString() + "deg)";
        backdrop.appendChild(elem);
        elem.animate(keyframe