The question of how the inverted position of a pendulum can be stabilized is of fun-damental importance for understanding human balancing tasks. Applications rangefrom postural sway during quiet standing to falls in the elderly to how expertisein a variety of balancing tasks is achieved including pole balancing at the fingertiptightrope walking, slack lining, skate boarding and so on. Since the “plant” is knownit is possible to develop mathematical models in concert with careful experimentalobservations in order to identify the nature of the neural control mechanism. Thesurprising mathematical observation is that the time delay plays an essential role inthe stabilization. The reader can test this for themselves by noting that it is easierto balance a longer pole at their fingerti than a shorter one. But then why does thepole always seem to eventually fall?This collaborative effort began from a chance meeting between the two authors ata workshop entitled “Noise, time delay and balance” held at the Banff InternationalResearch Station (BIRS) for Mathematical Innovation and Discovery, November 8-13, 2009. The motivating question has been whether the nervous system faces the same challenges controlling balance that a mechanical engineer faces in stabilizingmechanical structures.  weiterlesen