Entropy

Entropy is one of my absolute favorite concepts in chemistry. Simply put, entropy is a measure of disorder or randomness. For example, organizing your sock drawer by size and color - low entropy (order). Throwing your socks in a big messy pile - high entropy (disorder). Another way to think about it is that entropy measures the dispersal of energy. Pairing socks and placing them neatly in a drawer requires concentrated energy. However, pairing up socks all around the room disperses that energy expenditure throughout the room.

What's really cool about entropy is the second law of thermodynamics which states, "the entropy of an isolated system never decreases, because isolated systems spontaneously evolve towards thermodynamic equilibrium—the state of maximum entropy." And I'll add that there is no such thing as an "isolated system" within our capability. Let's say we try to create an isolated system by forming a completely sealed, hollow glass ball. Simply holding the ball in your hands changes the system by adding thermal energy (heat) to the gas inside the ball. The only real isolated system is the universe as a whole.

So, another way to state the second law of thermodynamics is this:
The universe is constantly moving toward a state of greater disorder.

Said another way: when order is created, it doesn't happen spontaneously. And when order is created somewhere, following the second law of thermodynamics, it must lead to an increase in disorder somewhere else.

This concept is one of my favorites because I like thinking that everything we do has some sort of effect on the universe. And in the same way, the universe affects us. 

There are other kinds of entropy, too. I was introducing entropy in the way that's most familiar to me - in terms of thermodynamics. However, there are many other studies of entropy, including social, genetic, economic, and informational.

Entropy in terms of information theory is a measure of uncertainty or randomness in a variable. So pretty much, everything I just said was to preface this really great comic/advice from xkcd.com. Enjoy! :)

Link to comic.