Hi Felix; You're right entropy doesn't always increase but it nevers decreases. Here is something you might find of interest from Wikipedia dealing with entropy, life, the arrow of time and gravity. [edit] Entropy and life Main article: Entropy and life
For over a century and a half, beginning with Clausius' 1863 memoir "On the Concentration of Rays of Heat and Light, and on the Limits of its Action", much writing and research has been devoted to the relationship between thermodynamic entropy and the
evolution of
life. The argument that life feeds on negative entropy or
negentropy as put forth in the 1944 book
What is Life? by
physicist Erwin Schrödinger served as a further stimulus to this research. Recent writings[
citation needed] have utilized the concept of
Gibbs free energy to elaborate on this issue. Tangentially, some creationists have argued that entropy rules out
evolution.
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In the popular 1982 textbook
Principles of Biochemistry by noted American biochemist
Albert Lehninger, for example, it is argued that the
order produced within cells as they grow and divide is more than compensated for by the
disorder they create in their surroundings in the course of growth and division. In short, according to Lehninger, "living organisms preserve their internal order by taking from their surroundings
free energy, in the form of nutrients or sunlight, and returning to their surroundings an equal amount of energy as
heat and entropy."
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The arrow of time
Main article: Entropy (arrow of time)
Entropy is the only quantity in the physical sciences that "picks" a particular direction for time, sometimes called an
arrow of time. As we go "forward" in time, the Second Law of Thermodynamics tells us that the entropy of an
isolated system can only increase or remain the same; it cannot decrease. Hence, from one perspective, entropy measurement is thought of as a kind of clock.
[edit] Entropy and cosmology Main article: Black hole thermodynamics
As a finite universe may be considered an isolated system, it may be subject to the Second Law of Thermodynamics, so that its total entropy is constantly increasing. It has been speculated that the universe is fated to a
heat death in which all the
energy ends up as a homogeneous distribution of thermal energy, so that no more work can be extracted from any source.
If the universe can be considered to have generally increasing entropy, then - as
Roger Penrose has pointed out -
gravity plays an important role in the increase because gravity causes dispersed matter to accumulate into stars, which collapse eventually into
black holes.
Jacob Bekenstein and
Stephen Hawking have shown that black holes have the maximum possible entropy of any object of equal size. This makes them likely end points of all entropy-increasing processes, if they are totally effective matter and energy traps. Hawking has, however, recently changed his stance on this aspect.
The role of entropy in cosmology remains a controversial subject. Recent work has cast extensive doubt on the heat death hypothesis and the applicability of any simple thermodynamic model to the universe in general. Although entropy does increase in the model of an expanding universe, the maximum possible entropy rises much more rapidly - thus entropy density is decreasing with time. This results in an "entropy gap" pushing the system further away from equilibrium. Other complicating factors, such as the energy density of the vacuum and macroscopic
quantum effects, are difficult to reconcile with thermodynamical models, making any predictions of large-scale thermodynamics extremely difficult.
. Network Nature. 
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