  Experimental evidence is presented connecting small fluctuations in the
posture of a quiet standing subject and the probability that the subject will
have an accidental fall within a time period of one year. The data can be
understood on the basis of random velocity fluctuations providing kinetic
energy in dynamical posture modes. The kinetic energy can activate a transition
over the a potential energy barrier which keeps subjects in a metastable
standing mode. The probability for a fall then follows an Arrhenius activation
law.
