  In this paper we are going to propose a physical model that can represent a
simple deterrence equilibrium situation, it is on based theory of unitary
rational actors. This theory takes in account that a state is composed of a
large number of people and a detailed study of the dynamics of any individual
it is impossible. This situation, in Physics, is similar for gases, which are
composed by a huge number of molecules and the study dynamics for one is
impossible. Then a common approach, in this case, is the thermodynamics one. We
only look to the macroscopic properties of the gas such as pressure,
temperature and volume. Then in this sense thermodynamics could help to use
theory of unitary rational actors also considering some non-rational factors.
Firstly we are going to see how this model represents the Mutual assured
destruction (MAD) theory if the influence of internal (economical,
political,due to non state actors) instability and o conventional military
forces are not taken in account. Secondly we are going to consider the factors
just mentioned in our model and we are going to study their influence on
deterrence stability: MAD will not be anymore effective. Finally we emphasize
that the proposed model can simulate the reaction to the interest of a
neighbour state or the international community on the deterrence equilibrium
situation. In particular we are going to apply this model to the India-Pakistan
deterrence equilibrium and see how the influence of International soft
diplomacy can change the situation.
