If you could go back in time to fix something in your past, would you do it?
Did I ruin time travel?
Is time travel possible?
There is a consensus among theoretical physicists that time travel to both the future and the past is possible. They don't even disagree anymore about how it would work. They don't know if someone could survive the trip in some cases. There has been a lot of math poured into these questions. I won't try to say I understand any of the math. Still, I can briefly explain a couple of theories that will at least get us to the place where we can speculate about traveling through time as a possibility instead of just fantasy.
Time Travel to the Future
This one is "easy." In his theory of relativity, Einstein stated that the closer you get to the speed of light, the more time slows down relative to people who are going slower. There is a whole light clock thing that illustrates how this will happen. I won't try to explain it. It's been done so many times. Watch this video if you want more info on this:
Anyway, people ARE currently traveling through time. Astronauts in the space station are presently suffering from time dilation. This means their clocks are going slower than ours (people on Earth), and they are traveling faster in time compared to us. Yes, I might not use all the correct terms, so go easy. Those astronauts are traveling milliseconds into the future.
Traveling into the future is pretty straightforward. You get a spaceship and go as close to the speed of light as possible. Maintain that speed for a year; when you return, over 2000 years will have passed on Earth. In a year, you could go 2000 years into the future. So going into the future is entirely doable. People are doing it right now. Time travel is easy; getting close to the speed of light is hard.
Time travel into the past
Wormholes or traveling faster than light are the 2 things that can get you back in time. If you go through a wormhole, you have the possibility of coming out of the wormhole at a different place and a different time. Let's go on faith. They got the math right here. There needs to be a thought experiment to make this simple. You can learn more about both here:
Grandfather paradox
We know it is theoretically possible to travel to the past and back to the future. It can work, so we are halfway there but wait. We also know that if we go back in time and accidentally kill our Grandfather, then we won't be born, and then we can't go back in time to kill our Grandfather, but if we don't kill our Grandfather, then we will be born and go back in time and accidentally kill our Grandfather. Yes, this is the grandfather paradox. Because of this paradox, some scientists like Stephen Hawking thought traveling back in time might be impossible. This is something scientists are still arguing about. So like all good theoretical thinkers, let's find a way around this paradox, shall we?
Multiverse
Some people have proposed that there are many universes out there; there are infinite universes where anything that can happen does happen. Most superhero films are using this approach right now. If you go back in time and tell yourself the winning lottery numbers, you'll be a rich man when you return to your future. You're not time-traveling; you're jumping from one alternate reality to another. Either way, this negates the grandfather paradox.
The paradox-free theory
Recently, researchers did the math, and they basically say that even if you go back in time to change something, the events will change to correct themselves. They say that the math checks out on this.
I'm not going down this rabbit hole. This is the version where you return to save your dog from getting by car on April 27, 2014. You save your dog, put him down, and bang, he's hit by another car. You go back again and book he's hit by a falling tree, then a lawn mower, then a bolt of lightning; no matter what you do, you cannot save your dog. This is unofficially known as the "this sucks for trying version of the universe." It seems to track, honestly, but let's say these researchers are wrong.
Quick recap so we are all on the same page
So now we all agree on these things
Traveling to the future is possible
traveling to the past is possible
only one of 3 theories, the multiverse theory, lets us make meaningful complete changes
So this means we are going back in time to recreate the future and play roulette with everyone's lives! Let's do it.
Multiverse or bust!
So we are going to go with the multiverse explanation. This gets us around the paradoxes and the annoyingly corrective, overly demanding universe and to a place we can speculate comfortably. Yes, I said all that to have a solid foundation of entirely theoretical mambo jumbo to ask this question If you could travel back in time to fix something in your past, would you do it?
Wait, let's think this out.
So if you go back in time to change the direction of your life, let's say a divorce, the death of a close person, or some terrible mistake you made in the past, then when you travel back to your future, things could be completely different. You go back to save Sally, your cat, from falling that well when you were 5, and when you return home, you find out the Nazis won the war and took over the world. Dammit, it's always the dang Nazi storyline. So you go back again, save Sally, change something, and then come back again, and this time, its donuts no longer exist, and everything is a wasteland. I hate the wasteland one, so you try again and again. Nazis, aliens, donuts, you're not doing well for a while until finally, you jump back, and you're rich! Your cat never died. Everything seems fine. People even seem happier and better off! Yay, you did it.
How would you ever know? There was no significant change in the timeline, but instead of your cat dying, the guy 3 doors from you has a car accident because the cat wasn't dead, and his whole family dies, and he's in a wheelchair. Are you willing to trade that? You would never know it. It's the push this button get a million dollars, but someone somewhere dies questions. So when considering time travel, we are considering taking responsibility for everyone on the planet. Would you do it? Are you ok with countless people dying to get what you want if you weren't aware of them dying? Did I ruin time travel for you?
When would anyone ever possibly go back?
Ok, so forgoing the idea that you're THAT GUY and you'd go back anyway just like you'd push the button, because who cares? Assuming you're not THAT GUY, when would it be a responsible thing to do to travel back in time?
Only if almost everybody is already dead, right? The only way we would ever try to return is if we didn't think we could make it any worse. Famous last words, but for the most part, if humanity was dying, Zombies took over, or there was some terrible virus or something, we might go back. Either way, time travel is a big responsibility, much bigger than fixing things in our own lives.
What about the other theories
The multiverse is only one of 3 theories here. In the other 2, you can observe all you want. You can't change anything. Go back in time and have a party! Live it up. When you return here, life will be just as crappy as before you left.
I might have ruined time travel for some people. I took the fun right out of it. If you think I did or didn't ruin it, leave me a comment. Leave a comment to tell me how wrong I am; that's fine, but please comment!