sisyphus

I think I basically agree, though I am pretty uncertain. You'd basically have to simulate not just the other being, but also the other being simulating you, with a certain fidelity. In my post I posed the scenario where the other being is watching you through an ASI simulation, and so it is much more computationally easier for them to simulate you in their head, but this means you have to simulate what the other being is thinking as well as what it is seeing. Simply modelling the being as thinking "I will torture him for X years if he doesn't do action Y" is an oversimplification since you also have to expand out the "him" as "a simulation of you" in very high detail.

Therefore, I think it is still extremely computation-intensive for us to simulate the being simulating us.

I get that doing something like this is basically impossible using any practical technology, but I just wanted to know if there was anything about it that was impossible in principle (e.g. not even an ASI could do it).

The main problem that I wanted to ask and get clarification on is whether or not we could know the measure of existence of branches that we cannot observe. The example I like to use is that it is possible to know where an electron "is" once we measure it, and then the wave function of the electron evolves according to the Schrodinger equation. The measure of existence of a future timeline where electron is measured at a coordinate X is equal to the amplitude of the wave function at X after being evolved forward using the Schrodinger equation. But I am guessing that it is impossible to go backwards, in the sense of deducing the state of the wave function before the initial measurement is made using the measurement result (what was the amplitude of the wave function at Y before we measured the electron at Y)? Does that make sense?

I thought David Deutsch had already worked out a proof that the Born rule using decision theory? I guess it does not explain objective probability but as far as I know the question of what probability even means is very vague.

I know that the branching is just a metaphor for the human brain to understand MWI better, but the main question I wanted to ask is whether or not you can know the amplitude of different timelines that have "diverged" a long time ago. E.g. it is possible to know where an electron "is" once we measure it, and then the wave function of the electron evolves according to the Schrodinger equation. The measure of existence of a future timeline where electron is measured at X is equal to the amplitude of the wave function at X after being evolved forward using the Schrodinger equation. But I am guessing that it is impossible to go backwards, in the sense of deducing the state of the wave function before a measurement is made using the measurement result (what was the amplitude of the wave function at X before we measured the electron at X)? Does that make sense?

I disagree with your 300 room argument. My identity is tied to my mind, which is a computation carried out by all 300 copies of my body in these 300 rooms. If all 300 rooms were suddenly filled with sleeping gas and 299 of the copies are quietly killed, only 1 copy will wake up. However, I should expect to experience waking up with probability 1 since that is the only possible next observer moment in this set up. The 299 dead copies of me cannot generate any further observer moments since they are dead.

I'd argue that you cannot experience a coma since you're unconscious, you can't really experience anything when you're in a coma. When you wake up it will feels as if you have just jumped forward in time. Deep sleep is qualitatively different and I was careful to avoid saying it is exactly like sleep, since sleep is simply a state of lowered consciousness instead of complete unconsciousness (e.g. we can still experience things like dreams). It is possible coma is also lowered consciousness like sleep, in which case you can experience comas but this says nothing about experiencing unconsciousness.

I think the main crux here is the philosophy of identity. You do not regard the emulated mind running on a machine on the other side of the room as "you", but if the subjective experiences are identical, you cannot rule out the possibility of being the emulated mind yourself. They are functionally identical and thus should be both considered "you" as they are carrying out the same computation.

"And to be consistent one would be adviced to "expect" at any moment to fluctuate into mars and choke for lack of air."

You're right that this is a probability and in a multiverse this possibility would be realised. But in this case the probability of it occurring is so little we needn't pay attention to it. This is qualitatively different from "low probability of being resurrected", because "teleporting to Mars" has a counterfactual experience of "not teleporting to Mars" which outweighs its probability, whereas "experiencing resurrection" does not have a corresponding counterfactual experience of "experiencing non-experience" since this is a tautologically meaningless statement.

"And it is not like the universe would suddenly abandon its indifference to human desire just for respecting non-destruction."

I am not saying the universe necessarily has to care about human experiences at all, just that death and nonexperience is a tautologically meaningless concept. In fact I'd rather the universe did not make me immortal.

"You seem to be arguing that you will experience "yourself" in many other parts of a multiverse after you die. Why does this not occur before you die?"

Because even though "you" in the sense of a computation have multiple embeddings in the multiverse, the vast vast majority of them share the same subjective experience and are hence functionally the same being, you can't yourself distinguish between them. The difference is that while some of these embeddings end when they die, you will only experience the ones which continue on afterwards (since you can't experience nonexperience).

"Can you clarify what you mean by "feel like falling asleep"? I don't see why there would be even a moment of unconsciousness if your idea is true."

I meant that death just feels like a timeskip subjectively. And you're correct that there wouldn't be any moments of unconsciousness, in fact this is already true in real life. You can't experience unconsciousness, and when you wake up it subjectively feels like a jump-forward from where you left off.

Yea my main question is that can we even in principle estimate the pure measure of existence of branches which diverged from our current branch? We can know the probabilities conditioned on the present but I don't see how we can work backwards to estimate the probabilities of a past event not occurring. Just like how a wavefunction can be evolved forward after a measurement but cannot be evolved backwards from the measurement itself to deduce the probability of obtaining such a measurement. Or can we?

I mainly picked "world where WW2 did not happen" to illustrate what I mean by counterfactual branches, in the sense that it has already diverged from us and is not in our future.

Huh, I thought that many people supported both a Tegmark IV multiverse as well as a Bayesian interpretation of probability theory, yet you list them as opposite approaches?

I suppose my current philosophy is that the Tegmark IV multiverse does exist, and probability refers to the credence I should lend to each possible world that I could be embedded in (this assumes that "I" am localized to only one possible world). This seems to incorporate both of the approaches that you listed as "opposite".