You can't go home again, right? That's a different time in a different place. In fact, everything and everyone is different, and they will remain so for all time. Or maybe not.Past, present, and future—every present-day step leads from a singular past to a limitless number of futures. Step this way, you're in one future. Step the other, you're in a different future. Step through a portal and there's no telling where you might end up.