Section 10.5
Section 10.5 Information and the Second Law
10.5Information and the Second Law
We have stressed earlier that work must be done to create and maintain the highly ordered local state of life. We now turn to the question, what else is needed for such local ordering to occur? Perhaps we can get an insight into this issue from a simple everyday experience. In the course of time, our apartment becomes disordered. Books, which had been placed neatly, in alphabetical order, on a shelf in the living room, are now strewn on the table and some are even under the bed. Dishes that were clean and neatly stacked in the cupboard, are now dirty with half-eaten food and are on the living room table. We decide to clean up, and in 15 minutes or so the apartment is back in order. The books are neatly shelved, and the dishes are clean and stacked in the kitchen.
The apartment is clean.
Two factors were necessary for this process to occur. First, as was already stated, energy was required to do the work of gathering and stacking the books and cleaning and ordering the dishes. Second, and just as important, information was required to direct the work in the appropriate direction. We had to know where to place the books and how to clean the dishes and stack them just so. The concept of information is of central importance here.
In the 1940s, Claude Shannon developed a quantitative formulation for the amount of information available in a given system. Shannon’s formula for information content is shown to be equivalent to the formula for entropy—the measure of disorder—except, with a negative sign. This mathematical insight formally shows that if energy and information are available, the entropy in a given locality can be decreased by the amount of information available to engage in the process of ordering. In other words, as in our example of the messy living room, order can be created in a disordered system by work that is directed by appropriate information. The second law, of course, remains valid: the overall entropy of the universe increases. The work required to perform the ordering, one way or another, causes a greater disorder in the surroundings than the order that was created in the system itself. It is the availability of information and energy that allows living systems to replicate, grow, and maintain their structures.
The chain of life begins with plants that possess information in their genetic material on how to utilize the energy from the sun to make highly ordered complex structures from the simple molecules available to them: principally water, carbon dioxide, and an assortment of minerals. The process is, in essence, similar in human beings and other animals. All the information required for the function of the organism is contained in the intricate structure of DNA. The human DNA consists of about a billion molecular units in a well-determined sequence. Utilizing the energy obtained from the food that is consumed by
10.5Information and the Second Law
We have stressed earlier that work must be done to create and maintain the highly ordered local state of life. We now turn to the question, what else is needed for such local ordering to occur? Perhaps we can get an insight into this issue from a simple everyday experience. In the course of time, our apartment becomes disordered. Books, which had been placed neatly, in alphabetical order, on a shelf in the living room, are now strewn on the table and some are even under the bed. Dishes that were clean and neatly stacked in the cupboard, are now dirty with half-eaten food and are on the living room table. We decide to clean up, and in 15 minutes or so the apartment is back in order. The books are neatly shelved, and the dishes are clean and stacked in the kitchen.
The apartment is clean.
Two factors were necessary for this process to occur. First, as was already stated, energy was required to do the work of gathering and stacking the books and cleaning and ordering the dishes. Second, and just as important, information was required to direct the work in the appropriate direction. We had to know where to place the books and how to clean the dishes and stack them just so. The concept of information is of central importance here.
In the 1940s, Claude Shannon developed a quantitative formulation for the amount of information available in a given system. Shannon’s formula for information content is shown to be equivalent to the formula for entropy—the measure of disorder—except, with a negative sign. This mathematical insight formally shows that if energy and information are available, the entropy in a given locality can be decreased by the amount of information available to engage in the process of ordering. In other words, as in our example of the messy living room, order can be created in a disordered system by work that is directed by appropriate information. The second law, of course, remains valid: the overall entropy of the universe increases. The work required to perform the ordering, one way or another, causes a greater disorder in the surroundings than the order that was created in the system itself. It is the availability of information and energy that allows living systems to replicate, grow, and maintain their structures.
The chain of life begins with plants that possess information in their genetic material on how to utilize the energy from the sun to make highly ordered complex structures from the simple molecules available to them: principally water, carbon dioxide, and an assortment of minerals. The process is, in essence, similar in human beings and other animals. All the information required for the function of the organism is contained in the intricate structure of DNA. The human DNA consists of about a billion molecular units in a well-determined sequence. Utilizing the energy obtained from the food that is consumed by