My brain groks this by considering it pass-by-reference vs. pass-by-value. The original you is the first instance. It occupies a particular place in space which

My brain groks this by considering it pass-by-reference vs. pass-by-value. The original you is the first instance. It occupies a particular place in space which you move about, and also experiences a particular path and timeline. As long as I'm considered alive, I'm adding to that path by moving around and interacting with the universe. You can keep finding and adding more details to get a unique picture of the first instance. The challenge here is easy because you only have to find one unique difference between the first instance and your copies to figure out which is which. It gets harder and harder to prove that one is perfectly equal to another. If you're building a copy of someone (regardless if the original is destroyed), that's pass-by-value. It's just making a copy at another memory location in the universe. If you're moving me around in a space ship, that's obviously pass-by-reference. If you're moving my soul (even with some limitations), that's pass-by-reference as well. What's convenient about this is that if you remove enough things from the soul enough that you can't know if it really is your soul, it casts doubt on how this transfer process was found out and proven in the first place, so we could reject the premise. But if you go and make a second copy of yourself (regardless of destroying the first), memories and personality and other things might be equal, but you can't replicate the path you took unless you can go back in time, so that will always be unique to the instance you're making a copy from. Teletransporters and brain implants are far, far more believable technologies compared to time travel. Experienced history is as much apart of you as your body and mind, and it's conveniently observable externally, so people don't have to trust your word that you're really 'you' or the first instance of you.