Definition of life

Definition of life:

All living entities can be defined as follows: the living entity uses energy to obtain energy and materials from the exterior at a first rate, converts the energy and materials into internal organization (“order”) at a second rate, and increases disorganization (“disorder”) external to the living entity.  The living entity converts the internal organization into energy which is used to obtain energy and materials from the exterior at the first rate, convert into internal organization, loop, etc.

This definition includes the following:

  • There is a volume of an entity (per the example of viruses, volume occupied by genetic code included).

  • Relative to the volume, there is an internal volume and an external surface area.

  • There is a rate of internal communication (“converts the energy and materials into internal organization... at a second rate”) and a rate of external communication (“uses energy to obtain energy and materials from the exterior at a first rate”).

  • Communication is defined as conversion between energy and order and visa versa. Nouns, internal communication, are order. Verbs, external communication, are energy.

  • The rate of communication is determined by the number of ordered states and the speed of switching between them.

  • The maximum relative ratio between external and internal communication is defined by the external/internal geometric scaling law of a sphere, which has an external/internal surface area/volume ratio of x2 to x3; add one dimension for time, and the ratio becomes x3 to x4, which is the allometric metabolic rate and body mass scaling law for all organisms (Kleiber's law) from bacteria, to trees, to whales (and corporations, governments, etc. -- see here).

  • The further the organism deviates from this maximum relative ratio, the less stable it is relative to external and internal perturbations.

  • Increases in the rate of internal communication allow the volume and external surface area of the entity to increase.

  • Reproduction over time requires conversion of energy into order; increasing external disorder is a necessary bi-product.

  • Reproductive entities exist on different scales, communication (energy-order conversion) being relative to an individuals as well as being relative to groups of individuals.

The above can be restated as: living entities (spanning from individuals to larger reproductive assemblies) continuously communicate external energy into internal order at a rate limited by the rate of internal communication, with a maximum external/internal communication ratio of x3/x4 . This ratio defines the boundaries of different reproductive assemblies and can be used to measure reproductive entities in computers.

Living entities exist to communicate and communicate to exist. Human communication media comprise genetic media (DNA) and social media (what we more commonly consider to be language: spoken, gesticulated, written, etc.). Social media can be faster than genetic media and can contribute to the reproduction of genetic media. Humans aren't the only creatures with social media. Many creatures exhibit social media, obvious examples include other primates and cetacians (whales, dolphins, etc.). A less well known example can be found in kuttlefish, which rapidly change their skin color, clearly communicating.

Social media has potential to manipulate the environment and to accelerate genetic media communication.  Social media benefits from a physical body with flexible ways to manipulate the environment. Humans, with hands, are able to create and use tools. Living in air (as opposed to water) allows use of fire, though aquatic environments carry the potential for chemically-based environmental manipulation.

How this differs from endothermic crystallization: endothermic crystallization is a reaction in which a crystal grows in a reaction which requires energy. An external energy source converts into order; a portion of the external energy is stored in the order. This differs from the above in that crystallization does not require continuous conversion between energy and order at a rate across a boundary. Endothermic crystallization does involve conversion between energy and order over time, but the conversion takes place on the surface boundary of the growing or contracting crystal. Unlike the crystal, life cannot be interrupted (though certain forms of life can be frozen or suspend activity for long periods).  Living entities have a flow of energy which forms a dynamic internal order. The internal order is converted into work, which obtains more external energy and re-creates internal order. Living entities inherit genetic mutations and are subject to natural selection.  In addition, endothermic crystallization does not involve an increase in external disorder relative to the internal volume?

For contemporary scholarship in this area please see the work of Jeremy England at MIT.