Entropy : or why is my house a mess?

   Physics is basically a bunch of descriptions (called "laws", "theories", "postulates", etc.) that allow us to predict how energy and matter (something that can be touched by other matter -- like a chair or oxygen or water) will be affected by other matter or energy that is applied to the original system. Note that, with special relativity (the old famous Einstein equation of E = mc**2) it is recognized that energy can be converted into matter and matter can release energy if broken into less complex units. (As usual, it is easier to break something down than to put it together.)

   One concept is called entropy. This is a measurement of disorder. It applies to the melting of an ice cube. It applies to the complexity of atoms -- with entropy increasing when fission occurs breaking a uranium atom into smaller atoms. It can also be used for everyday things -- such as a tidy room becoming messy. In each case, the situation of order moving towards disorder is called entropy.

   Local entropy can be reorganized. This often requires putting in energy -- but not always. The free flowing molecules of liquid water are less organized than that of ice which has a static configuration and form. In order to create ice from water, it is necessary to remove heat (energy). Because there are different ways that order is created from disorder (or disorder from order), there are considered to be different types of entropy.

   Notice that I say local entropy. According to the Second Law of Thermodynamics, the overall process of entropy cannot be reversed. If you leave something alone, it will eventually break down. In a house, everything will get covered in dust. A moving part will wear and break. Radioactive particles will continue to convert into non-radioactive masses.

   So, whether one believes in creationism or the big bang theory, everything started in chaos, order was imposed, and everything keeps trying to make its way back to chaos. We can clean the dishes but they'll get dirty again (even if we don't use them, dust will settle).

  Next time you look into your house and say "didn't I just clean this up the other day?" just tell yourself -- "Oh yes, entropy".