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In order to appreciate what we mean by 'far from equilibrium' we first need to start by understanding what is meant by 'equilibrium'. We can understand equilibrium using two examples: that of a pendulum, and that of a glass of ice cubes and water.
If we set a pendulum in motion, it will oscillate back and forth, slowing down gradually, and coming 'to rest' in a position where it hangs vertically downwards. We would not expect the pendulum to rest sideways, nor to stand vertically from its fulcrum point.
We understand that the pendulum has expended its energy and now finds itself in the position where there is no energy - or competing forces - left to be expended. The forces exerted upon it are that of gravity, and this causes the weight to hang low. It has arrived at the point where all acting forces have been canceled out : equilibrium.
Similarly, if we place ice cubes in a glass of water, we initially have a system (ice and water) where the water molecules within the system have very different states. Over time, the water will cool slightly, while the ice will warm slightly (beginning to melt), and gradually we will arrive at a point in time where all the differences in the system will have cancelled out. Ignoring the temperature of the external environment, we can consider that all water molecules in the glass will come to be of the same temperature.
Again, we have a system where competing differences in the system are gradually smoothed out, until such time as the system arrives at a state where no change can occur: equilibrium.
In a complex system, we see very different dynamics: part of the strangeness of emergence arises from the idea that we might see ice spontaneously manifesting out of a glass of water! This is what we mean by 'far from equilibrium': systems that are constantly being driven away from the most neutral state (which would follow the second law of thermodynamics), towards states that are more complex or improbable. In order to understand how this can occur, we need to look at the flows that drive the system, and how these offer and ongoing input that pushes the system away from equilibrium.
Lets take a look at one of our favorite examples, and ant colony seeking food. Lets start 100 ants off on a kitchen table (we left them there earlier when we were looking at Driving Flows. The ants begin to wander around the table, moving at random, looking for food. If there are crumbs on the table, then some ants will find them, and direct the colony towards food sources through the intermediary signal of pheromones. As we see trails form (a clear line forming out of randomness like an ice cube fusing itself out of a glass of water!), we observe the system moving far from equilibrium. But imagine instead that there is no food. The ants just keep moving at random. No emergence, nothing of statistical interest happening. When we remove the driving external flow (food) that is outside of the ant system itself then the ants become like our molecules of water in a glass. Moving around in neutral, random configurations. Eventually, without food, the ants will die - arriving at an even more extreme form of equilibrium (and then decay)!
Photo Credit and Caption: Far From Equilibrium
Cite this page:
Wohl, S. (2019, 23 October). Far From Equilibrium. Retrieved from https://kapalicarsi.wittmeyer.io/definition/far-from-equilibrium
Far From Equilibrium was updated October 23rd, 2019.