Thermodynamics

## Energy Generation and Flow This is ultimately limited by some basic physics, some of which we understand (Thermodyanmics) and some of which we don't (Chaos). Even though a system may appear to be very simple, the behavior of that system might be chaotic. There is an important difference between chaos and complexity , although the two are often referred to as the same thing. Java Applet Alert Complexity can have predictability Game of Life Another Example Chaos, on the other hand, is complexity which is undetermined, that is, the behavior of the system can't be predicted, or more to the point, can't be predicted without an infinite amount of information. The elements of chaos theory are hard to describe. Here is an example called the Chaotic Pendulum For us, today some neutrally buoyant helium balloons floating around class today can also serve as an example of a chaotic system. In Class Chaos Demo Helium balloons and a demonstration of the principles of chaos: Unstable equilibrium (a perturbation in either direction causes an irrecoverable situation) No predicative power, our neutrally buoyant helium ballon can go in any direction Random interactions will occur that would not otherwise occur (e.g. whose head is this balloon going to fall on). These random interactions will increase the chaos of the system (student x bats balloon in some direction). An external event which is not in the interactions reduces the chaos (e.g. the helium runs out and the balloon falls on the floor). The nature of the chaotic system is continuously changing i.e. its difficult to maintain the neutral buoyancy of the balloon. When its not neutrally buoyant, its less chaotic and more deterministic. In principle, the motions of the ballon are entirely governed by physics, hence if we knew all the physics we would have predictive power. However, the amount of information which is required to be known is nearly infinite. So even though the helium balloon is a simple system, its motion and its interaction with other elements is chaotic. Chaos seems to exist in a variety of natural systems to some extent or another The Flow of the McKenzie River The Greenhouse effect Hurricane evolution Planetary orbits Evolution of species THERMODYNAMIC LAWS You can not subvert or change these laws: The Zeroth Law (0): Systems are in equilibrium when they are at the same temperature. System is in it lowest energy state No more energy can be extracted from it All systems of different temperature will tend to equilibrium when they are no longer thermally isolated. See the Movie Modelling Thermodynamic Equilibrium: (

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The First Law (1): Energy is Conserved in a closed system:

• The net flow of energy across some system is equal to the change in energy of that system
• We usually consider work and heat flow as the two kinds of energy

The Second Law (2): The Law of Entropy:

• It is not possible to extract heat-energy from a reservoir and perform work without creating waste heat that does no work.
• The amount of disorder increases
• Things tend toward a state of randomness(this is not the same as chaos)
• You can not go from a disordered system to an ordered system without inputting more energy (this is the most important attribute of the second law)

Example:

We can do this

100% of electrical energy converted to heat by pushing a current through a resistive element.

We can not reverse that process to do this:

In the course of doing the original work we have increased the disorder to the system by heating it. In no way can we recover work of that this disordered system without putting energy into the system.

To decrease local entropy requires work (energy).

• Your dorm room - it takes a lot of work to decrease the amount of disorder

• Iron Ore is originally concentrated in mountains - has a low disorder. Eventually it becomes mined and ends up distributed in the nations landfills.

• This combination of letters is readable and hence of low order but