Epistemic Status: ~70% confidence, hoping to get some feedback.
I'm going to argue that if we accept three controversial (but not outlandish) assumptions to be true, then subjective death (the cessation of conscious experiences identifying themselves as "you") is impossible. I will keep this post as concise as possible.
Here are the three assumptions:
- We live in a multiverse (e.g. the MWI or Tegmark's MUH is true).
- Consciousness can be simulated computationally.
- Identity is "transmitted" through similarity of observer-moments.
Given assumption 1, somewhere "out there" (e.g. in a different Everett branch), there will be worlds that contain "revival simulations" of you (simulations of you being revived and regaining consciousness after your death).
Given assumption 2, these simulations will be conscious and have subjective experience.
Given assumption 3, these revival simulations of you are technically "you" since "you" of this instant is a particular observer-moment that is being computed in a multitude of quantum branches or universes. Your identity is transmitted through the continuity of similar observer-moments since these simulations possess the same memories as you before you died (and hence connect with your last observer moment).
Similar to how the quantum immortality argument says that even though your "reality measure" is reduced after an experiment, you are guaranteed to survive from your perspective because you cannot subjectively experience the branches where you die. Here the argument is that when you die, there will be quantum branches or other universes computing observer-moments of "you" experiencing a revival. Hence you should always expect to be revived after death.
These conclusions sound pretty crazy to me intuitively, but if one accepts the assumptions (whether or not those assumptions are true is outside the scope of this post), these conclusions feel quite straightforward.
You should read Greg Egan's excellent novel Permutation City.
Will do, have heard great things about it!