You mean that planet Earth exists in many universes in parallel? (Rather than that there are many different planets, in different universes? but not "copies" of Earth)

Maybe there are also many parallel Earth like planets in this particular universe, with human like creatures. Some of which have, some have not.

To state that as if it were incontrovertible fact, with no evidence given, seems a bit presumptuous.

This is possible, but probably represents a drastic misunderstanding of MWI/QM. I’d you’re thinking I. Terms of branches from quantum superpositions, then it would be a certainty, but a certainty among u counted multitudes. If you’re thinking Quantum Suicide... just no. Nuclear war does not fulfill the requirements of that gedanken.

> If you’re thinking Quantum Suicide... just no. Nuclear war does not fulfill the requirements of that gedanken.

Could you elaborate on why? I'm not seeing why it couldn't be couched in similar terms (replacing the box with Earth, the radiation source with nuclear war, and the cat with people) -- is it because you can't treat the Earth as a closed system in the same way?

In quantum suicide, your means of death must be both the result of a quantum superposition, and 100% lethal... otherwise you might just be in this universe, horribly maimed. Now, a nuke on your lap with the trigger hooked up to sense the decay (or not) of a given radioactive material is probably valid, but global nuclear war? No way. Odds of surviving all out nuclear war Are pretty lousy, but decidedly non-zero.

But the number of people living in a non-nuclear apocalypse world will be much higher than the number of people living in a nuclear apocalypse world (assuming the probability of a nuclear apocalypse is less than like 90% or something). Your death in a nuclear apocalypose doesn't necessarily have to be a 100% probable for you to experience this non-nuclear apocalypse world with some high probability.

That’s not a superposition or probabilities, and not really subject to this thought experiment. What you’re describing sounds more like quantum immortality, not related to suicide. The problem either way is that you only get to make your own observations... maybe that means you die, and in a branch you don’t. You don’t experience that branch though, if it exists. You don’t have any awareness of other branches now, right?

The problem is... why and how does your consciousness “move” to another reality? What is the physical mechanism that has you living and not a twin in another universe who isn’t really you... after all, you died when the bombs fell.

Most Of all though it’s important to remember that like Schrodinger’s cat this is a thought experiment meant To illustrate certain problems or features of quantum mechanics. It is an analogy or metaphor for a system dominated by quantum effects, like a single radioactive atom with a 50-50 chance of decaying in the next second. These thought experiments don’t really suggest alive/dead cats, or immortals, they highlight how quantum systems differ from Classical ones.

These ideas have led to various interpretations of QM, such as The Copenhagen Interpretarion (wavefunction collapse) and MWI (multiple universe). None of those interpretations are very rigorous, and may well be indicative of gaps in understanding as much as anything else.

Which one is Fallout?

This.

Surprisingly enough, a human is much more likely to find oneself alive in a world in which humanity was not nearly made extinct by nuclear war.

Exponentially so, if we assume, reasonably, that even if humans survived (technically) a nuclear war, their descendants would take 100s of thousands of years or longer to recover to pre apocalypse levels, vs. non nuclear war realities where the population simply keeps increasing exponentially, leading exponentially many more humans to find themselves existing in that "timeline."

This also explains why, despite my suicidal driving, I am miraculously alive.