ABSTRACT
The material properties of living things for many physical scientists can be summarized as those of soft condensed matter. This phrase describes a range of physical states that in essence are relatively easily transformed/deformed by thermal energy fluctuations at or around room temperature. This means that the free energy scale of transitions between different physical states of the soft condensed matter is similar to those of the thermal reservoir of the system, namely, that of ~kBT, where kB is the Boltzmann constant of ~1.38 × 10−23 m2 kg s−2 K−1 at absolute temperature T. In the case of this living soft condensed matter, the thermal reservoir can be treated as the surrounding water solvent environment. However, a key feature of living soft matter is that it is not in thermal equilibrium with this water solvent reservoir. Biological matter, rather, is composed of structures that require an external energy input to be sustained. Without knowing anything about the fine details of the structures or the types of energy inputs, this means that the system can be treated as an example of nonequilibrium statistical thermodynamics. The only example of biological soft condensed matter, which is in a state of thermal equilibrium, is something that is dead.
