THE DIRECTION OF TIME THE DIRECTION OF TIME

THE DIRECTION OF TIME

 THE DIRECTION OF TIME 


ABOUT THE DIRECTION OF TIME

The direction of time is directly related to the irreversibility concept and the second law. This seems to be a rather strange statement. The direction of time appears so obvious in our world; shouldn’t that be as fundamental as other basic physics concepts—directions, masses and so on, instead than being based on the elusive second law. The point is that the basic laws of physics, the laws of Newton, the quantum mechanical laws or even the laws of relativity theory all do lack a direction of time. (We will come back to the question of general relativity theory). In the description of, for instance, planetary motion there is nothing that tells about a direction of time; that enters when we consider the energy transformation processes in the Sun and the transfer of heat to the earth and the other planets. The direction of time seems to be a consequence of the second law, and then be a characteristic of the macroscopic world, not the atomic world with general, time-reversible laws. A book dealing with various aspects of these questions is (Halliwell et al., 1994). There are attempts, most notably by Prigogine to get a more fundamental role of the direction of time, but it seems that we rather should cope with it: the direction of time is an expression of the irreversibility postulated in the second law. Prigogine’s view (1980) is that there is a fundamentally broken symmetry with the terminology, we had in Section 16A. We will in this chapter go somewhat deeper in fundamental processes than in most of the book, out from the earth and out from the consideration of life (although we will get back there at the end). And we may start by a still deeper question: What is time? How do we comprehend time? Do you think you understand it? Think a little further. There is a classical quotation by St. Augustine that says something like: “When I don’t bother, I know what time is, but when I think about it, I don’t know.” This simple statement uttered long ago can be repeated at any time. There is something strange with the time concept, different from, for instance, distances. It is not clear how to characterize time. I have a view on that, related to the biological view on certain basic (macroscopic) concepts discussed in chapter 2. We humans have good ideas about distances and structures in the environment. That is needed in order to find our way, to find food (in the woods as well as in a grocery store). But we don’t need to understand time for that purpose
the direction of time is an expression of the irreversibility postulated in the second law. Prigogine’s view (1980) is that there is a fundamentally broken symmetry with the terminology, we had in Section 16A. We will in this chapter go somewhat deeper in fundamental processes than in most of the book, out from the earth and out from the consideration of life (although we will get back there at the end). And we may start by a still deeper question: What is time? How do we comprehend time? Do you think you understand it? Think a little further. There is a classical quotation by St. Augustine that says something like: “When I don’t bother, I know what time is, but when I think about it, I don’t know.” This simple statement, uttered long ago can be repeated at any time. There is something strange with the time concept, different from, for instance, distances. It is not clear how to characterize time. I have a view on that, related to the biological view on certain basic (macroscopic) concepts discussed in chapter 2. We humans have good ideas about distances and structures in the environment. That is needed in order to find our way, to find food (in the woods as well as in a grocery store). But we don’t need to understand time for that purpose

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