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Time/Newton/mechanics/Genz: in Newtonian mechanics, not only the earlier point of time determines the later point of time, but also vice versa the later determines the earlier one.
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Isaac Newton.
Deterministic/Genz: we must distinguish between forward deterministic laws and forward and backward deterministic laws.
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Laws, >
Natural laws.
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Question: are there also purely backwards deterministic laws?
Definition Time/Genz: as long as we do not know anything else, we can simply define time as the direction in which deterministic laws of nature apply. This is necessarily identical to the direction in which the order cannot increase.
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Time, >
Space, >
Time reversal, >
Time arrow, >
Order, >
Symmetries, cf. >
Chirality.
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Deterministic/time/forward/backwards/quantum mechanics/Genz: the deterministic laws of quantum mechanics are deterministic in both temporal directions.
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N.B.: but it does not say whether they are the same in both time directions!
The fact that they are not the same was first shown directly by an experiment in 1998.
Before: the "CPT theorem" had already made the same prediction:
CPT-Theorem/Genz: the CPT-Theorem says together with the "CP violation" that backwards deterministic laws of quantum mechanics must differ from forward deterministic laws.
Experiment 1998: a K-Meson (neutral) can develop into its anti-particle. This can also be done in the opposite direction, but the process must then proceed more quickly (asymmetry).
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N.B.: then we can decide from the laws of nature alone, whether we have a real process that takes place in time, or whether a backwards running film is shown by a physical process.
Not time-reversal-invariant: for example, the transformation of a K-Meson into its anti-particle is not time-reversal-invariant.
Experiment: has of course not been observed directly, but by observations on numerous particles in the same state.
Asymmetry/Genz: asymmetry only applies to the duration of the process, not to it itself.
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Asymmetry.
