What Does This Mean?
In our previous article, we saw how the fact that entropy is always increasing means that the universe will end in an inglorious heat death, along with everything living in it. How does this inexorable march, like that of lemmings approaching the Norwegian coast and hurling themselves off, indicate this?
When entropy increases, the amount of energy available for work decreases. We say that the quality of the energy involved has been permanently degraded. Orderly mechanical energy transformed to the disorderly form of thermodynamic energy is one form of this degradation.
An example is when a ball, moving forward with all of its particle going basically in the same direction, hits a wall in a collision that is not totally elastic. Kinetic energy is released, and the ball and the wall have a slight increase of thermal activity i.e. temperature change. The ball bounces off with less kinetic energy than it originally had, along with some random motion imparted to it by the temperature increase, and with its capability of doing useful work reduced.
Living things actually cause a decrease in entropy. This is how you can maintain your body heat, grow five fingers and toes, and are able to help create other living beings, for example. But you are not an isolated system. You interact with the universe and in doing so, you increase its entropy.