Nature is exciting, and the more we learn about nature, the more we see how everything is woven together. Since mankind started using tools and used the tools to create houses and equipment and industrialized the world, focus has been on one issue a time. History shows that such approach can lead to unpleasant results. This approach is, however, understandable. The ability to handle complex issues require means able to describe several processes interacting with each other simultaneously. Up until now, such means has not been available.
Not only is the nature woven together, but it is also dynamic. Nature is not fixed; it is changing all the time. The traditional approach is to assume stationary conditions. Treating a dynamic process as stationary, will lead to wrong results.
An example of a multiphysic and dynamic process, is depressurization of a vessel exposed to fire:
The fire increases the vessel steel temperature. However, the over all rise in temperature depends on the temperature of liquid and gas on the inside, and the heat transfer that depends on the pressure inside which again depends on the rate of evaporation rate of the liquid. The rate of evaporation depends on the pressure and the temperature that depends on the release rate of gas or liquid that again depends on the pressure. We have not mentioned yet the change in composition of the liquid and gas as the pressure and temperature change. The strength of the steel depends on the type of steel and the temperature of the steel. The steel gets weaker the higher the temperature is, and if pressure inside gets higher than the steel can take, the vessel will rupture. In a multiphysic dynamic simulation, such events can be predicted. Welcome to the multiphysic world.