ENTROPY.         
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Thanks to: " HFAL", " Bored chemist", Bill Skocpol and
 Jim Whitescarver I corrected and wrote this article.

 Entropy. / My opinion /.
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1.   
Henry Poincare  named the conception of "entropy "
as a " surprising abstract ".
2.
 Lev  Landau (Dau) wrote:
" A question about the physical basis of the
entropy monotonous  increasing law remains open ". 
3.
The famous mathematician  John von Neumann said to
"the father of information theory" Claude Shannon:
 " Name it "entropy"  then in discussions
 you will receive solid advantage, because
nobody knows, what "entropy"  basically is ".
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1.
Between 1850 - 1865 Rudolf Clausius published a paper
 in which  he called " The energy conservation law" as
 " The first law  of  thermodynamics". But in our nature the
 heat always flows  from the higher temperature to the
 lower one and never back.  In our everyday life we don't see
 the heat itself rises from cold to hot. So, it seemed  that
 in thermodynamics " The energy  conservation law"
wasn’t  kept, this law was broken. But Clausius had another
opinion. He thought: I know people believe  that this process is
irreversible, but I am sure that " The energy conservation  law"
 is universal law and it must be correct also for thermodynamic
process. So, how can I save this law ?
Probably, in the thermodynamic process  there is something
 that we don't  know. Maybe, there is some degradation
 of the total energy in the system which never disappears .
Perhaps, there is some non-useful heat, some unseen process ,
some unknown  dark energy , some  another form of potential
 energy/heat itself which can  transform  heat  from the cold
 body to the warm one. I will call  this conception as " entropy"
and it will mean that changes of entropy (dS) can be calculated
for reversible process and may be defined as the ratio of the
 quantity of energy taken up (dQ) to the thermodynamic
 temperature (T), i.e. dS= dQ /T.
And because I don't know how this process goes I won't call
it as a law but as " The second principle of thermodynamics "
which says that " the entropy of an isolated system always
  increases ". Another version: " No process is possible
 in which the  only result is the transfer of heat from a hotter
 to a colder body.  It is possible some reversible process which
 is unknown now ."
2.
Between 1870 - 1880  Ludwig  Boltzmann said:
" Clausius is right. But I can add more to his entropy conception.
First.
According to Classic physics when an isolated thermodynamic
 system comes to a thermal equilibrium all particles stop their
 moving. From one hand it is correct. But the system cannot be
 at thermal equilibrium (in the state of thermo death) all the time.
 The situation in the system must change.
Therefore I say  that at the thermal equilibrium  the entropy
(some unknown dark/potential energy ) of the system will
reach maximum and as a result , the thermal  equilibrium
 of the system will change.
Second.
I don't know how exactly  the  thermal  equilibrium of the system
 changes. But I can give  probabilistic / statistical interpretation
of this changing process.  I can write " The second principle of
 thermodynamics" by a formula: S= k log W and this formula
says:" the entropy ( heat) of the system is the collective result of
mechanical motion and  friction of all the particles (k)."
I will call it as " The second law of Thermodynamics."
3
In 1900 Max Planck said:
Clausius and Boltzmann are both right.
But all my life I worked almost exclusively on problems
 related to thermodynamics. And I am sure that the " The second
 law of Thermodynamics" , concerning entropy, is deeper and it
 says more than is generally accepted. I am sure the Boltzmann's
probabilistic /statistical version of "The second law of
Thermodynamics "  is not  completed, is not final.
Please, look at the graph of the radiation curves of the " black body".
They are very similar to those curves which are calculated
by Maxwell for the velocity (i.e. energy)  distribution of gas
molecules in a closed container. Could this black body radiation
problem be studied in the same way as Maxwell's ideal gas....
...electromagnetic waves ? This problem of connection  between
radiation of black body and Maxwell's Electrodynamics theory
doesn't give me peace. Maxwell's theory can tell everything
about the emission, absorption and propagation of the radiation,
 but nothing about the energy distribution at thermal
equilibrium. What to do? How to be ?
After trying every possible approach using traditional
classical applications of the laws of thermodynamics
I was desperated. And I was forced to consider that the
relation between entropy, Boltzmann's  probability version
and Maxwell's theory  is possible to solve by suggestion ,
 that  energy is radiated and absorbed with discrete
  individual  quanta particle (E= hv). So, now I must write
 " The second law of Thermodynamics " by formula:
                          hv = k log W.
But if I look to the Clausius inequality I see that entropy
 is energy divided per temperature.
 So the formula hv = klogW is  hv = kT logW  I think.

 I was so surprised and sceptical of such interpretation  the
 entropy  that  I spent years trying to explain this result
in another , less revolutionary way. It was difficult for me
 to accept this formula and to understand it essence .
It was hard for me to believe in my own discovery.
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My conclusion.
How to understand this formula?
Which process does formula (hv = kT logW ) describe ?
1.
In 1877  Boltzmann suggested that the energy/mass state
of a physical system (of ideal gas ) could be discreted.
 This idea was written with formula: R/N=k. It means:
 there are particles with energy/mass state (k) in physical
system of ideal gas  . They dont move, they are in the
 state of rest.
2.
 In 1900 Planck followed Boltzmann's  method of dividing.
Planck suggested that energy was radiated and absorbed
with  discrete "energy elements" - " quantum of energy"-
- " Planck's action constant"- (h) . This fact means:
electron produces heat, setting in mechanical motion and
 friction  all particles. This fact is described with Planck's
 formula:   hv = kTlogW.
3.
In which reference frame does this process take place?
In thermodynamical reference frame of ideal gas and
black body (M. Laue called this model as Kirchhoff,s vacuum).
Now it is considered that these models  are abstract ones which
do not exist in nature. On my opinion  these models explain
  the situation in the real Vacuum (T=0K) very well.
4.
 For my opinion the formula (hv = kT logW ) says:
a)
The reason of " entropy" , the source of thermal equilibrium's
fluctuation , the source of Vacuum fluctuation is an action of
the particle /electron, which  has energy: E = hv  (hf).
b)
The process of Vacuum fluctuation depends on collective
motions of all particles (k) and will be successful if enough
 statistical  quantity of Boltzmann's  particles ( kT logW)
 surround the electron.
c)
Which process does the formula (hv = kT logW ) say about ?
This formula describes the possibility of realization of
macro state from micro state. This formula explains
the beginning conditions of gravitation,
the beginning conditions of star formation.
1.
 hv = kT logW.
    hv > kT logW.
    hv < kT.
2.
 hv --> He II --> He I -->
( P. Kapitza , L. Landau , E.L. Andronikashvili theories).
(Superconductivity,  superfluidity.)
 3.
Plasma reaction... -->
4.
Thermonuclear  reactions ...-->......etc.

d)
Thanks to Entropy the homogeneous Vacuum is broken.
Thanks to Entropy the micro process changes into
macro process.
Thanks to Entropy the stars formation takes place.
Thanks to Entropy " the ultraviolet catastrophe" is absent.
Thanks to Entropy our Milky Way doesn't change into radiation. 
Thanks to Entropy the process of creating elements takes place.
Thanks to Entropy the process of evolution is going.
e)
One physicist  said :" The entropy is only a shadow of energy“.
Maybe now somebody can understand  why  entropy is a shadow.
And maybe now somebody will understand why
" The  Law of conservation  and transformation of energy"
 is also correct for thermodynamic system.
fg)
Why is " The second law of Thermodynamics"
so universal?  Because it is based on
 " The  Law of conservation  and transformation of energy"
And this law is not the simple accounting solution of debit and credit.
 The sense of this law is dipper and it says more than is usually accepted.
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P.S.
 It took me about three months to write this brief article.
Plus about three years searching for the key of entropy problem.
Plus about twenty-three years trying to understand the essence
of physical laws and formulas.
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 #
 [A law] is more impressive the greater the simplicity of its
premises, the more different are the kinds of things it relates, and
the more extended its range of applicability. Therefore, the deep
impression which classical thermodynamics made on me. It is the only
physical theory of universal content, which I am convinced, that
within the framework of applicability of its basic concepts will never
be overthrown.
/ Albert Einstein/
#
The law that entropy always increases -- the second law of
thermodynamics -- holds I think, the supreme position among the laws
of Nature. If someone points out to you that your pet theory of the
universe is in disagreement with Maxwell's equations - then so much
worse for Maxwell equations. If it is found to be contradicted by
observation - well these experimentalists do bungle things sometimes.
But if your theory is found to be against the second law of
Thermodynamics, I can give you no hope; there is nothing for it but to
collapse in deepest humiliation.
/ Sir Arthur Stanley Eddington /
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Best wishes.