Voltage efficiencies below 100% reflect the thermodynamic irreversibility of every real-world chemical reaction. The idea of "irreversibility" is central to the understanding of entropy. Current research in dynamical systems offers one possible mechanism for obtaining irreversibility from reversible systems. Another major theme is entropy and the irreversibility of time. According to Prigogine, determinism loses its explanatory power in the face of irreversibility and instability. This is an example of hysteresis, switching barriers, and irreversibility. Research on irreversibility in quantum mechanics takes several different directions. Another problem of natural and social capital deterioration lies in their partial irreversibility. Centration, conservation, irreversibility, class inclusion, and transitive inference are all characteristics of preoperative thought. A prime example of irreversibility is in the transfer of heat by conduction or radiation. This carries the connotation of irreversibility. Death penalty opponents regard the death penalty as inhumane and criticize it for its irreversibility. With irreversibility, the arrow of time is reintroduced to physics. Irreversibility of natural processes, he claimed, is a purely relative conception. The following is a list of spontaneous events which contribute to the irreversibility of processes.