Reversibility vs Non-reversibility

Fleissner, Peter
 Incorporated contributions
Fleissner (28/02/09)
 Usage domain
transdisciplinary, System theory
Reversibilité vs Ireversibilité 
 German Reversibilität vs Unreversibilität

Reversibility and Non-reversibility or Irreversibility are properties of systems with respect to inner changes. In a rigid analysis there is never such a thing like complete reversibility, because on the macro-level and for physical systems the stream of time cannot be reverted, i.e. in the space-time continuum only movements toward increasing points in time are possible. If we abstract from time, still pure reversibility is impossible in closed systems – as we know from thermodynamics -because any change which is accompanied by a difference cannot be performed without a loss of energy, and, in general, with an increase of entropy (although according to Ilya Prigogine a decrease of entropy = an increase of order could be possible locally). As far as we know today, irreversibility is a general property of all processes in evolution: on the cosmic, geological, phylo-genetic, onto-genetic, social or economic levels. Reversibility can only happen if we abstract from energy/entropy changes.

For practical purposes it is important to know if qualitative or quantitative changes can be compensated or not. (e.g. pathological changes in tissue or organs, chemical reactions). Jacob Segal (1958) gives the following degrees of reversibility:

  1. spontaneous and directly revertible processes (with losses in time and energy)

  2. spontaneous and indirectly revertible processes (on different pathways than under 1.)

  3. non-spontaneous, but directly revertible processes (additional energy necessary)

  4. non-spontaneous, but indirectly revertible processes (new side-conditions needed)

  5. absolutely irreversibility



  • SEGAL, Jacob (1958). Die dialektische Methode in der Biologie. Berlin: Dietz Verlag.
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Fleissner (28/09/09)
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