Ectropy
Encyclopedia
In thermodynamics
, ectropy is a measure of the tendency of a dynamical system to do useful work and grow more organized. Ectropy, in a loose sense, can be thought of as the opposite of entropy
. Ectropy is minus entropy
. That is, instead of saying "lose entropy
" you can say "gain ectropy", instead of saying "gain entropy
" you can say "lose ectropy".
The term was introduced in the late 20th century by mathematician and philosopher Willard Van Orman Quine
and is often more intuitive than its counterpart. The term's merit is that in order to understand a concept, it can be useful to look at it from the other side. Sloppily speaking, ectropy signifies order; slightly more exactly, usable energy. Actually, what we call energy is often ectropy.
The Earth
, for example, gets electromagnetic waves from the sun
and sends electromagnetic waves back into space, but the incoming waves have shorter wavelengths (higher frequencies) and therefore more ectropy. So the Earth's ectropy is increased by the sun. When we eat
, we take in ectropy from the food.
The Second Law of Thermodynamics
says that in a closed system, ectropy will decrease. An organism
which is isolated from the outside world will die and deteriorate because its ectropy decreases. It needs ectropy coming from the environment to keep living.
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, ectropy is a measure of the tendency of a dynamical system to do useful work and grow more organized. Ectropy, in a loose sense, can be thought of as the opposite of entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
. Ectropy is minus entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
. That is, instead of saying "lose entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
" you can say "gain ectropy", instead of saying "gain entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
" you can say "lose ectropy".
The term was introduced in the late 20th century by mathematician and philosopher Willard Van Orman Quine
Willard Van Orman Quine
Willard Van Orman Quine was an American philosopher and logician in the analytic tradition...
and is often more intuitive than its counterpart. The term's merit is that in order to understand a concept, it can be useful to look at it from the other side. Sloppily speaking, ectropy signifies order; slightly more exactly, usable energy. Actually, what we call energy is often ectropy.
The Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, for example, gets electromagnetic waves from the sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and sends electromagnetic waves back into space, but the incoming waves have shorter wavelengths (higher frequencies) and therefore more ectropy. So the Earth's ectropy is increased by the sun. When we eat
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
, we take in ectropy from the food.
The Second Law of Thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
says that in a closed system, ectropy will decrease. An organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
which is isolated from the outside world will die and deteriorate because its ectropy decreases. It needs ectropy coming from the environment to keep living.
See also
- NegentropyNegentropyThe negentropy, also negative entropy or syntropy, of a living system is the entropy that it exports to keep its own entropy low; it lies at the intersection of entropy and life...
- ExergyExergyIn thermodynamics, the exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir. When the surroundings are the reservoir, exergy is the potential of a system to cause a change as it achieves equilibrium with its...
- Extropy
- Free entropyFree entropyA thermodynamic free entropy is an entropic thermodynamic potential analogous to the free energy. Also known as a Massieu, Planck, or Massieu-Planck potentials , or free information. In statistical mechanics, free entropies frequently appear as the logarithm of a partition function...
- Entropy in thermodynamics and information theoryEntropy in thermodynamics and information theoryThere are close parallels between the mathematical expressions for the thermodynamic entropy, usually denoted by S, of a physical system in the statistical thermodynamics established by Ludwig Boltzmann and J. Willard Gibbs in the 1870s; and the information-theoretic entropy, usually expressed as...