Would we even know if we traveled back in time?
This is a little sci-fi.
I'm not a physicist or a philosopher, but I'm interested in how the universe works. One thing I'm curious about is time. Believe it or not, nobody really knows how time works, and effects like time dilation show that time does not work the way we intuitively think it does. Personally, I think time is like an undirected graph of cause and effect (or effect and cause), a directionless web of events, even though it feels like it has a forward direction.
When folks start talking about this, they inevitably mention that it's not possible to travel backward in time. There's a problem with that statement, though, and it only occurred to me recently. When people say it's not possible to travel back in time, or that entropy tends to increase, and so we don't generally see wine glasses unshatter and float back to their original resting places, they're really saying that it's not possible for external events to move backward in time while they themselves move forward in time. Why should that be possible? Why should someone be able to retain their memories and continue aging while everything around them reverses? That would be like the food in my oven cooking while the food in my microwave becomes cold again. Maybe it's simply not possible for time to “move in two directions” at once; the events that led me to start the oven also led me to start the microwave. How could one set of events be reversed without the other?
Maybe backward time travel does happen, but we don't notice it. By analogy, if we were living in The Sims and the “player” decided to rewind the game, causing the most recent frames to be played back in reverse order, wouldn't our memories and experiences also be undone frame by frame? Wouldn't it feel exactly like experiencing it “forwards”, one “frame” or one moment at a time? The “me” from a frame one hour ago would have the idea to write this post, and he wouldn't have the memory of having already started it.
I know this is pretty out there, as far as my posts go. Maybe this is easily refuted by people who actually know what they're talking about. But it's interesting to me. And hey, maybe it would make for a fun Star Trek plot point! “We are going back in time, we just don't remember it!“