What does the second law of thermodynamics have to do with your relationships? At FamilyLife® we tell people to be intentional about their relationships. Why? Because of entropy. Entropy is the unavailability of a system’s thermal energy for conversion into mechanical work. It’s the gradual decline of a system into disorder. Boy, did that hurt my brain. Okay, it’s why your mobile phone needs to be recharged and why the sun will burn out in 5 billion years. Relationships are like an old grandfather clock; if you don’t wind them up every once in a while, they stop working.