So, if time travel is possible, there are some pretty big (near as I can figure) inevitable consequences that will totally change how you think about the world. This is a bit involved, so let’s start with some story time.
That Time the British Burned Down Washington, DC
So, August 25, 1814, President Madison and his staff have fled the capital, and the invading British troops are really getting into the Burning of Washington, after kicking our American asses at Bladensburg. They’re getting busy checking the Presidential Mansion (first White House) and Capitol off their “This is for the Tea” list, when, wham! comes a tornado!
It rolls straight down Constitution Avenue, burying a bunch of British troops under the rubble, and tossing their artillery around like they were Monopoly pieces. Not only does the storm put out all the fires the poor British worked so hard to light, except for the one at the Presidential Mansion, which was set alight by Canadian troops–needless to say, if Canadian fires could be put out by weather, all the Canadians would have died long ago–and the British are forced to retreat to their heavily damaged ships to sail away.
Now, you could, and many people did, see the Hand of God in this. It’s the first recorded tornado in DC history, and only one for an entire century thereafter, had hit at the precise place and moment to prevent the destruction and possible capture of the American capital.
Now, history is replete with such moments, and, in fact, we were rather the bad guys in the good ol’ War of 1812, but, still, I mean, that’s one hell of a coincidence, right?
This gets us to time travel.
Time travel, at least in one direction, is definitely possible. The big question is whether we can reach back in time. If time travel isn’t possible, then none of this matters. If time travel is possible, though, it sort of narrows down the nature of reality a bit. For example:
If time travel is possible, then there is an eternal war, and a God, sort of, must exist, if there’s time travel.
See, if it’s possible to reach back in time, then, in the vastness of infinite possible futures, someone must be doing so. The odds are infinitely close to 100%. Let’s say you invent a time machine, though . . . you’re probably a government or a big company, not one dude. So what’s the first thing you’re going to do?
You’re going to reach back in time to eliminate anything leading up to your competition. It’s entirely possible that time travel is actually really easy to do, and future people are just making tiny, tiny, changes to make sure it never comes together. A power surge here, a misplaced grant application there, and all of a sudden you’ve bought another century of no competition.
Eventually, though, other people will figure it out. Governments will figure it out, or whatever replaces them. Presumably more and more of them, as time goes on. What happens, then, is we’ve got this big tangled tree of possible futures, all of which can reach back down the branch to change things.
It’s not just America, Russia, and Oceania or the Mars Republic, or whoever, fighting over it, though. It’s America 1, America 2, America 761, etc. There’s lots of potential players here.
With me so far?
I hope so, because this is where it gets cool, and kinda plausible as more than a fun little thought experiment.
The big question, then, is: If this is going on, why aren’t we seeing evidence of it all the time, everywhere?!
Easy. If you’re tinkering with time, in the past, and you do anything overt, then anyone who opposes you down after the point of the branch where you make the change can simply go back and make that not happen. So, by necessity, you, and they, have to be really sneaky. You can only change things in small ways that have big consequences.
Plus, if you do anything that makes it obvious to a timeline that time travel is possible, you’re suddenly looking at a lot more competition in the time travel market.
You aren’t going to kill Einstein or Hitler. You’re going to make a banker late so that he bumps into Einstein on the way to the store and interrupts his train of thought just before he figures out how to make the Arrow of Time point backwards. You’re going to shuffle some papers to meddle with the launch date of the Mongol Fleet so that an unseasonable typhoon sinks their invasion fleet on the way to Japan, and the Japanese Empire continues to exist right up until it attacks Pearl Harbor and draws the US into World War II.
If you change the past in a way anyone can detect, then you’ve already failed.
Alright, I hope that makes sense, because things are about to get even crazier.
All Possible Futures
As we move down the timeline, all of the timelines, there are two possible long-term options: Either we go extinct (and cease to meddle with the past) or we reach some crazy endpoint of advancement. Basically, down every branch of that tree is either a pruned twig, or at least one fully flowered god-like-something-or-other.
So, if time travel is possible, we are currently unknowing participants in a battle between all possible futures, and therefor all possible gods, to ensure their eventual existence.