ELI5: Explain Like I'm 5

Conservation law (physics)

Conservation laws are rules in physics that describe how energy, momentum, and other physical properties are kept the same over time. They sort of act like rules in a game that make the game work. So it's like a game of catch: you throw the ball to someone, they throw it back to you, and the number of balls stays the same. In physics, these laws help make sure things keep working the same way all the time.