It is the sadness of the age-old ‘Oh, what could have been’ that must be distinguished from ‘what can I do now?”
It has been argued as a virtually irrefutable truth that physical interactions at the submicroscopic level of our reality are all reversible. Whereas it is demonstrably irrefutable that at our macroscopic level of existence all physical processes are irreversible. But as with so many difficult questions, the reasoning on this issue is plagued by categorical errors. In this case one categorical error is in confusing what could have been done in reverse with what can subsequently be reversed.
It is true that virtually every molecular interaction could have been reversed. This is certainly true for elastic collisions of any kind as shown below. And despite Boltzmann’s efforts to prove otherwise no number of such interactions can ever result in the irreversibility of entropy.
Unrestricted interactions mediated by inelastic particle exchanges where role reversal still applies, are also inconsequential at producing irreversibility. The interaction can persist even as the impacts of the interactions diminish over time. In the following sequence the mediation is accomplished by throwing and catching a baseball.
A direct reversal of the players’ velocities at any point in the sequence would toss by toss restore their altered status until they were once again in close proximity with zero relative velocity. Thereafter they would proceed to drift apart again. In short, their interactions are reversible. Energy and momentum are conserved whether velocities are reversed or not.
A direct reversal of the players’ velocities at any point in the sequence would toss by toss restore their altered status until they were once again in close proximity with zero relative velocity. Thereafter they would proceed to drift apart again. In short, their interactions are reversible. Energy and momentum are conserved whether velocities are reversed or not.
In subsequent posts I’ll demonstrate how these restrictions apply to photon interactions between molecules leading to the explanation of entropy.
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