  Peace means order, and war brings disorder and chaos to any society. But
order and disorder are not only observed in wars, in many systems they are the
dominant property. Understanding order and disorder enables us to understand
the structure of systems. Order and disorder are also part of the Lagrange
Principle, and as statistics is valid in all systems, we may regard Lagrange
statistics as a mathematical basis of system science. Two systems out of
natural and social science are compared: materials of trillions of atoms and
politics of millions of people. Lagrange statistics leads to three phases of
homogeneous systems: in materials we have the states: solid, liquid, gas,
depending on two Lagrange parameters, temperature T (the mean energy of atoms)
and pressure p. In politics we have three states: autocratic, democratic,
global, depending on two Lagrange parameters, standard of living T (the mean
capital of people) and political pressure p. The three phases of each system
are compared in the p-T phase diagram: Different phases of one system cannot
coexist as nearest neighbors: Water will dissolve ice by exchange of atoms and
heat. This leads to the present climate crisis. Democracies will dissolve
autocracies by exchange of goods, ideas, and people like guest workers. This is
the peaceful history of the EU and has led to the aggressive reaction of Russia
in the GDR, Hungary, \v{C}SR, and now in the Ukraine. At the end of war
peaceful coexistence will not be possible between Russia and Ukraine. Only
separation by a new Iron Curtain guaranteed by NATO can lead to a long-time
armistice.
