The answer to the basic question "what is aging?" is now here. It follows by several decades the answer to "what is life?" This answer was provided by physicist Erwin Schrödinger in his seminal series of lectures at Trinity College, Dublin in 1944.
In fact these two fundamental questions -- "what is life?" and "what is aging?" -- have an important relationship. They are similar but different.
The question "what is aging?" is even more encompassing than "what is life?" because everything in the universe ages while only living things live. Stars, canyons, and Chevies age. But redwoods and turtles and we age but are also alive.
My personal fixation on exploring answers to these questions goes back 50 years when I pulled off my right Achilles tendon skiing in Vermont. After miserable 8 weeks the cast came off and I beheld my leg which was puckered, wasted, and painful. It was old. Except that it wasn't because the other leg was just as old and it was fine. Nor was it because the tendon was ruptured as the surgeon could've put the cast on my good leg and the same thing would have happened. My leg became precociously old because it was in a cast.
Why? There was nothing in the medical textbooks that provided the answer.
So I had to figure out why. First I listed the essential components of health, three: energy, matter, and time. These three components find a unified expression within the domain known as thermodynamics, that is the essence of health, and much else. Thermodynamics was formulated more than a century ago to explain the workings of the steam engine. The First Law is simple, energy is conserved, neither created nor destroyed. But it is the Second Law where the real fun exists. It is a cosmic Murphy's Law. An imperative. The Second Law says that energy spreads. It has to disperse. It has a distributive property. Ever since the Big Bang of a long time ago the Universe has been expanding. In spreading it becomes less concentrated, hot things cool, mountains crumble, ice becomes vapor, order becomes disorder. The feature of Time is an expression of this mandate. It is uni-directional.
The answers to "what is life?" and "what is aging?" both derive from the dispersion of energy. The word for this change in process is "entropy." Pursuing this survey I wrote an article "Disuse and Aging" in the JAMA in 1982 pointing out that the erosive variety of changes attributed to aging and those due to disuse were virtually identical. The contemporary emergence of Space Medicine provided important references because space travel is accelerated aging.
Why is exercise good for everything? Also, why is lack of exercise bad for everything? Consequently, the central precepts of the Second Law of Thermodynamics are essential to these questions. In 1986 I wrote another article "Aging as entropy," further endorsing this relationship. Aging is the effect of an energy flow on matter over time. This definition explains why energy flow is the central component of the process. Optimum flow corresponds to the Greek observation of the Golden Mean, not too much, not too little. It echoes loudly .
With this background last week I joined Leonard Hayflick to conduct a pre-conference seminar at the annual meeting of the Geronto-logic Society of America in Washington DC. Our workshop was entitled "the Second Law of Thermodynamics and the Etiology of Biologic Aging." We received immense support from the Glenn Foundation for Medical Research and its director Mark Collins. Leonard is the premier gerontologist in the world. His work with cells in tissue culture revealed that living cells had only a limited lifespan putting the notion of immortality in the waste basket. His observation goes by the common term "Hayflick Limit." Leonard has received immense recognition for his work, lacking only the Nobel which was absurdly withheld. But Leonard's singular observation was subsequently inappropriately awarded elsewhere.
Later he wrote an essential article in the New York Academy of Medicine entitled "Aging is no Longer an Unknown" in which he adopted the precepts of the Second Law as his explanatory platform. Hence our meeting last week. A dozen experts from Europe and U.S. discussed our topic. We agreed that the prior terms to provide a causation of aging as a disease or as a genetic defect were impoverished. Seeking the explanation for "what is aging?" commanded a new paradigm, a new conceptual framework beyond disease and beyond the gene. In their place the Second Law appears as the proximate and ultimate cause of aging. Tom Kirkwood gave a highly sculpted paper asking "does the concept of life contain within it the seeds of its own destruction?" Energy spread is creative and destructive. It is both the cause of life (Schrodinger) and the cause of its destruction, due to the aggregate of many entropic processes including DNA damaging, reactive oxygen molecular generation. mishandling of protein molecules, all of which are evidences of entropy. Energy flow is the important lesson. It is the progenitor of order and its eventual decay. Life exists between chaos and order. Let us all seek to make the most of this middle way.