   # the steps involved in one go of the universe's clock
   go: ->
     @timer ||= new Date()
-    unless @dead
+    unless @dead || !@change
+      @change = false
       @goTime = new Date()
       @tick += 1
       self = @

  moveThing: (thing) ->
    [ vx, vy ] = thing.velocity 
    return unless vx || vy
    thing.x += vx
    thing.y += vy
    if thing.x < 0

    @setAttributes options
    @others = {}
    uni = @universe
    uni.change = true
    [ @x, @y ] = location
    @velocity = [ 0, 0 ]
    @radius ||= 5
