Changes

==Entropy and disorder ==

==Entropy and disorder ==

In this context "increasing disorder" means "that which happens if you let nature take its course."

In this context "increasing disorder" means the decline in organization that occurs without intelligent intervention. Imagine your old room at your parent's house.  Remember how easy it was to let the room turn into a uniform mess (disorder) and remember how hard it was to clean it up until it fit a specific, non-uniform design (order).  Not cleaning up would always result in an increase of entropy in your room!

Imagine your old room at your parent's house.  Remember how easy it was to let the room turn into a uniform mess (disorder) and remember how hard it was to clean it up until it fit a specific, non-uniform design (order).  Not cleaning up would always result in an increase of entropy in your room!

Now, in nature there is no one to clean up the universe, only chances.  The chance of something becoming orderly is a lot smaller than the chance of something becoming disorderly (since there are far more possible disorderly states to choose from).

Now, in nature there is no one to clean up the universe, only chances.  The chance of something becoming orderly is essentially zero, which it is a certainty that things will become more disorderly.

 

Alternatively one could think of how difficult it is to construct a house of cards, while almost everything that happens in nature will result in its collapse.

On a universal scale a tidy room would be a universe which has pockets of above average concentrations of energy (if you - incorrectly - assume relativity [[E=mc²]] this includes matter as well.)

On a universal scale a tidy room would be a universe which has pockets of above average concentrations of energy (if you - incorrectly - assume relativity [[E=mc²]] this includes matter as well.)

A messy room would be a universe in which all energy is equally spread out.

A messy room would be a universe in which all energy is equally spread out.

The flow of energy (by heat exchange) to places with lower concentrations is called the "heat flow".

The flow of energy (by heat exchange) to places with lower concentrations is called the "heat flow."

The often heard argument that this law disproves an eternal universe is true, since in that case maximum entropy would have been reached already. A counter-argument to this would be to suggest that the universe is still in the process of approaching maximum entropy.

The often heard argument that this law disproves an eternal universe is true, since in that case maximum entropy would have been reached already. A counter-argument to this would be to suggest that the universe is still in the process of approaching maximum entropy.

There are many different ways if stating the second law of thermodynamics. An alternative statement of the law is that heat will tend not to flow from a cold body to a warmer one without work being done, e.g. by a [[refrigerator]]. It can also be losely stated as "[t]he universe is constantly getting more disorderly!"<ref>The quotation is from Isaac Asimov, who continued to say "[v]iewed that way, we can see the second law all about us.  We have to [[work]] hard to straighten a room, but left to itself it becomes a mess again very quickly and very easily.  Even if we never enter it, it becomes dusty and musty.  How difficult to maintain houses, and machinery, and our bodies in perfect working order: how easy to let them deteriorate.  In fact, all we have to do is nothing, and everything deteriorates, collapses, breaks down, wears out, all by itself -- and that is what the second law is all about.” Isaac Asimov, Smithsonian Institute Journal, June 1970, p. 6.  Put in physics terminology, the Second Law states that the [[entropy]] of an [[closed system|isolated system]] never decreases.</ref> Other statements include that it is impossible for an [[engine]] to convert [[heat]] perfectly (I.e. at 100% efficiency) into [[work]]. These statements are qualitative and stating the second law in terms of [[entropy]] makes the law quantitative.

There are many different ways if stating the second law of thermodynamics. An alternative statement of the law is that heat will tend not to flow from a cold body to a warmer one without intelligent invervention, or work, being done, as in the case of a [[refrigerator]]. Other statements include that it is impossible for an [[engine]] to convert [[heat]] perfectly (I.e. at 100% efficiency) into [[work]]. These statements are qualitative and stating the second law in terms of [[entropy]] makes the law quantitative.

This law makes it impossible to build a [[perpetual motion machine]] - the increase in entropy inevitably derails the system even if its [[energy]] remains constant (as described by the [[Conservation of Energy|first law of thermodynamics]]).

This law makes it impossible to build a [[perpetual motion machine]] - the increase in entropy inevitably derails the system even if its [[energy]] remains constant (as described by the [[Conservation of Energy|first law of thermodynamics]]).