Probably one can speak about time in any situation where you compare changes relative to some fixed system of reference. Maybe, one-dimensional time seems to us quicker, so usually we think that time is one-dimensional. But I think there could be also a more-dimensional time. Such considerations lead, in my opinion, also to the conclusion that there is not much sense in speaking of the "first two seconds of the universe" and so on. If one should make a very simple definition of time, probably one could say that time is the changement in a standardized domain of changement. In this definition time could also be reversible. Psychologically on the other hand we speak perhaps about time when we feel things are not more reversible. One could say, we have to find for any realm of nature the appropriate concept of time. This means, we have to define for this realm a small set of controllable parameters whose changement allows us to follow the overall evolution of the events we are interested in. I think, you agree that this doesn't mean only a difference in scale, but (in non conventional or extreme situations) also in type. Now thinking about, one could imaging a 2-dimensional time, or a ramifying time, and so on. When however this complex time can be thought of as evolving along a simpler time concept, then we may stick to that one. So it seems, that time has something to do with irreducibility. I think, we are back to Kant. The task is to discuss the relationship between the reality we created inside ourselves and the real reality outside of us. What do you mean, when you say, that some things are timeless? ------------------------------------------------ [Jerry to me] Ah -- what things are timeless? I consider this a very beautiful, profound question, Josef! To say that time is change, we imply that timelessness is changelessness; to view time as change, we attempt to explain our perception of it; to view change as time, we attempt to measure it. So something timeless does not change; it is measureless. The concepts of "zero" and "infinity" are timeless; the concepts of certain principles and ideals (as in absolute geometric figures, good and evil, etc.) are timeless. The absolute concepts exist in our minds as "ideas" which cannot be perceived literally by sight, hearing, taste, touch or smell: the physical senses. For this reason, I would suggest that our understanding of something like "timeless", "zero" or "infinity" is in actuality a "sixth sense": abstract logic (not "E.S.P."). These abstract concepts, I might add, do not depend on a human vehicle to exist. They are simply "there", and humans are merely capable of "discovering" them. Trying to live without this sixth sense would handicap us in the same way as a lack of one of the other physical senses; however, in one respect, it would be more severe, since human happiness is so dependent on abstract perceptions. ------------------------------------------------ In your descriptions time comes out as a psychological concept, involving "humans", "perception", even "ideals". Is this a contradiction to more physically oriented, more "absolute" definitions? I don't know whether your definition could be the basis of a mathematical definition of time, but when we consider that intelligent beings in fact exist and therefore are a part of nature, we should perhaps accept that the mechanisms of mind can be involved in the definition of the other events. Even when one asks, how could be the time for other intelligent beings, probably we could hope that a principle, which one could call a convergence principle, brings the components of truth always near to each other (I think, very primitively, that computers become more similar to each other the better they become, that intelligent people have usually rather similar ideas independently of their experiences, that some kinds of beauty are very similar), so that other intelligent species should have developed logical mechanisms similar to ours. I mean, more concretely, the following: If your definition, based on our psychology, is true for us, it could be true also for a superior species, if only we are careful enough not to violate the fundamental logical rules. In this sense I would agree (I think such ideas were very popular in Europe 100-200 years ago) that triangles, infinity (I have to think about, what this means, however), zero, good, evil are timeless concepts, if (and only if) some intelligent species survives. Otherwise the other, the absolute definition (see Darin's and my contributions) would apply. I think that the fact that certain ideas (as the number two, probably one of the most fundamental concepts) are installed in practically every human being, shows that these ideas derive from laws of nature existing outside man. Philosophers have struggled (until philosophy had some consideration in human society) a long time for understanding what existence means. These are so difficult questions, in which the mechanisms of our mind are so deeply involved, that one can give only crumbs of truth. Perhaps we have to decide that anything was ever perceived, even by one only being, has to be defined as to be existent, and that the essential question is how all these existent things are connected among them. You have very clearly explained the significance of time in our human conscious life. But, possibly, in the evolvement of physical systems, other categories of time are necessary. It seems that in the course of this discussion it came out that time is a very general concept, which appears in many contexts. Similarly, for example, if we were being discussing the question "What is communication?" we had to distinguish communication between persons from communication between molecules, say, or between elementary particles. All these communications have some abstract properties in common, and have to be treated differently in other aspects. ------------------------------------------------ [B.R.] Since time doesn't exist, one must look for ways to describe our existence without the use of terms that assume the concept of time. We look at a rock and say it is very old or we see a person and say he/she has aged. This is an illusion. Something has happened to the rock or person. The only way to understand it without using "time" loaded concepts is to say that it is a different rock or person. It is not the same object before us that we have in our memory. To say an object is different may seem like begging the question or simplistic. I agree it is simplistic and certainly doesn't begin to describe what is going on but at least it is real (whatever that means). ------------------------------------------------ [To B.R.] I don't find it simplicistic, I never heard this idea about time so clearly stated. From the mathematical point of view it is very satisfying thinking of time as of something which holds together the various states of the same system.