|Time: A. Time is a dimension in which events are arranged. At first, no direction (before / after) is defined with this. A time direction can be obtained in the context of the Second Principle of Thermodynamics. However, a global framework must be assumed, within which there is an increase of entropy. The assumption of increasing entropy does not apply to the comparison of local events. B. In the case of the subjective time, the question of direction is less problematic. The perceived time direction is expressed by the learned use of the terms "before" and "after". See also time arrow, time travel, time reversal, symmetry, duration, space time, relativity theory, four-dimensionalism, world lines._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. |
Time/time direction/time reversal/Vollmer: the designation of a time direction is empirical and is made always only secondarily by additional assumptions - e.g. initial conditions in the mechanics and thermodynamics - rediance conditions in electrodynamics.
Time/logical form/Vollmer: temporal relationships can be expressed by real functions t(e1, e2) that are defined on event pairs. - Asymmetry: is then a formal property of this function to change the sign at reversal - this has nothing to do with reversibility of physical processes, also not with designation of one direction. - Time Reversal: only formal operation of changing the sign.
Invariant: is a formula that does not change under time reversal. - Time reversal invariance: So is a property of formulas or functions. - E.g. Newtonian equation of motion. - On the other hand: the question of whether natural processes are reversible, relates to the real world. - Problem. a T-invariant equation can describe both reversible and non-reversible processes. - If, then it does not yet contain complete information.
Definition Time Arrow/time direction/Vollmer: so we will call the fact that there are chains of events, whose part events never happen in reverse order - time direction is not a characteristic of the time, but of processes - that there are different classes of irreversible processes, there are different arrows of time: the expansion of the universe, the electrodynamic of spherical waves - that a process is irreversible, one cannot see that in looking at it. - It can also never be proven. - Causality/cause/effect/VollmerVsReichenbach: cannot define the arrow of time. - Reversed: these are not to defined without time arrow.
Irreversibility/Physics/time reversal/time arrow/Vollmer: We expect that the fundamental equations, equations of motion, laws of force, field equations are T-invariant, that is, that they change with time reversal.
Entropy/universe/Boltzmann/Vollmer: for him, the universe as a whole is in a thermodynamic equilibrium, so in the entropy maximum.
VollmerVsBoltzmann: the observations state the contrary. If we advance into more distant parts of the universe, we can always find low entropy. - If there were a region of space with decreasing entropy (increasing order), there would also be irreversible processes, but some time arrows would be reversed._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
Was können wir wissen? Bd. I Die Natur der Erkenntnis. Beiträge zur Evolutionären Erkenntnistheorie Stuttgart 1988
Was können wir wissen? Bd II Die Erkenntnis der Natur. Beiträge zur modernen Naturphilosophie Stuttgart 1988