If you've ever watched an ice cube melt or stirred creamer into a pool of black coffee, you've witnessed a fundamental truth about the universe: The "arrow of time" always marches forward.
Time flows from past to future. What we call the present is a never-ending series of inflection points, where the collection of events that have already happened (the past) meets the collection of events that have yet to happen (the future). And while time doesn’t ever stop, it can slow down.
