I've heard most of the arguments for or against backward time travel, but I was wondering one thing - wouldn't the "butterfly effect" exclude time travel into one's own past? Basically, any effect you have on the past makes a minute effect, but one that becomes large enough, after the passage time, to change the memory, and therefore the mind, of your former self, so that you are not the same exact person by the time you enter the wormhole, so you cannot have the memories you have right now and probably have not even entered the wormhole (or time travel device or flown next to the rotating cylinder, whatever you are using) at the same time and in the same manner, so you can't change the past in the exact same way, and so on. I haven't seen anybody bring this up, and I was wondering if there was an answer to that. I don't really buy the "restricted past" theory. It seems unlikely that everything will go perfectly so that you're unaffected.