The McFly Scheme

[SRP76]

Meh, you and your butterfly effect. Screw that. I'm still in. And even if you did alter history, no big deal. Make your bet, cash in, and then go back a couple more years. Wash, rinse, repeat. You start with a fresh timeline each trip. Then what happens when you want to go home? You're not going to want to stay in 1911. With all those alterations, you could end up materializing in the middle of Mad Max Land or something. Not good.

[JDFP]

I think its doubtful that there would be any major lasting implications of your actions of returning back in time to make a bet on a sporting event. But every thing you do will cause a ripple. It's one thing to go back in time and go see a concert or make a bet on a game and buy a cheeseburger -- it's a completely different thing to go back in time and become a senator or kill someone (or possibly both). The ripples are bigger. There's also the issue of how far back in time you go -- the greater the distance the greater the impact of your actions (like Bradbury pointed out in some of his great work). I always preferred the parallel universe theory myself. If you return back in time then return back to your time you're not really returning back to your time at all but a parallel future created through your excursion in the past. To put it another way, you can't change the past in your universe. You can, potentially, create a new universe through your actions though. Here's a good one for you: Say you return back in time and interact with yourself 20 years younger. You approach yourself and say: "Hey, you're going to meet a girl named Sarah Smith at a party in a few years -- stay the hell away from her." One of two things would take place: 1.) Your past self says: "Your crazy" and think nothing about it and go on like normal. 2.) Your past self believes your future self and decides to follow your advice. If your past self follows your advice and stays away from this girl -- it would dramatically change your life. Thus, if you were in the same universe, then you would simply either 1.) cease to exist as having returned back in time to tell your past self this news in the first place because you've dramatically altered your future and never became the person to travel back in time to warn yourself or 2.) even if you still grow up to be a time traveler and traveled back in time to warn your past self you wouldn't know to warn your past self about this specific girl because you yourself didn't know about her. In essence, you just completely canceled the entire equation out. You can't change the past. The alternate to this is that you just created a parallel universe through your actions. You warn yourself and your past self accepts what you tell your past self. But you then look at your hands -- and hey, you haven't disappeared from existence! You also still have your former memories from your own life not changed by your actions -- in essence, there are now two of you in existence -- the you who returned in time and the new you just created in this parallel existence through your actions. When you return back to your own time -- nothing has changed though because you return back to your own time line (because you can't change your past in returning to your own time) or you return to your future to discover there is another you that you just created because you're now stuck in this alternate time-line you created. Ah, hell... I could really get into this much deeper... Time travel discussions are a fun form of mental masturbation. j.p.

[SRP76]

All I know is that if it weren't for a member of the Q Continuum, Woodstock would never have happened.

[Trin]

We have to consider that we're arguing in the BttF universe. And we know that changes to the past affect the future in the same timeline. As evidenced by Marty starting to fade away when his actions change his parent's future. We also know that Biff did NOT have this problem. Since he traveled back in time within his own lifespan he never compromised his existence, just changed his potential future.

[bassman]

We also know that Biff did NOT have this problem. Since he traveled back in time within his own lifespan he never compromised his existence, just changed his potential future. Funny that you mention that. Biff was originally supposed to be "erased from existence" when he returned the delorean to 2015. The only thing that made it into the final film is him acting like he's in pain when getting out of the car, but originally the scene was to go on and he'd fade away. The idea behind it was that Marty's mom shot and killed the millionaire 80's Biff. Go Loraine!