Peil J
Arch Gerontol Geriatr. 1986 Jul;5(2):97-105. doi: 10.1016/0167-4943(86)90013-0.
The aging process is understood as the temporally changing ability of the organism to maintain the degree of inner order and organisation which is necessary for viability. This inner order and organisation may be represented by a multidimensional state variable 'vitality'. The quantity 'vitality entropy' is defined in a manner similar to information theoretical or thermodynamical entropy. It is an aggregate measure of the age-dependent distribution of vitality in the state space. In these terms a mathematical description of the aging process may be given as temporal changes of the extension of this distribution. In an initial phase of differentiation of an organism the vitality entropy decreases to a minimum as the distribution becomes concentrated at the optimal states. With aging in the narrower sense, the distribution spreads in the state space with the decrease of order and organisation, and the consequent increase of vitality entropy.
衰老过程被理解为生物体维持对生存至关重要的内部秩序和组织程度的随时间变化的能力。这种内部秩序和组织可以由多维状态变量“活力”来表示。“活力熵”的定义方式类似于信息理论熵或热力学熵。它是状态空间中活力随年龄分布的综合度量。从这些方面来看，衰老过程的数学描述可以表示为这种分布范围的时间变化。在生物体分化的初始阶段，随着分布集中在最优状态，活力熵降至最低。在狭义的衰老过程中，随着秩序和组织的减少，分布在状态空间中扩散，活力熵随之增加。
