One of the fascinating aspects of the Second Law of Thermodynamics is its relation to our understanding of time.  Think about almost any video you have ever watched.  Do you think you would be able to determine whether or not the video is running forwards or backwards?  We simply recognize that some processes do not happen spontaneously.  A pendulum that initial hangs straight down doesn’t suddenly begin to swing back and forth, going a little farther each time, without something doing work on the pendulum to get it to begin swinging.  But a pendulum that is swinging will certainly swing less and less as it swings back and forth, until it finally comes to a stop.  The fact that we see only one of those scenarios as a possible future outcome is related to entropy.  Equilibrium states are the highest entropy state for a system.  For thermodynamics systems which often contain more than 10²³ particles, the likelihood of a system being in equilibrium completely dwarfs the odds of it being in any other configuration.