Cessation of Existence is incompatible with the leading models of "standard physics" as presented at the level of core grad school physics classes. Now, I don't entirely subscribe to those models but I do understand them well enough to have aced all my core theory classes (lab was a shameful B...) so I actually have 'more weight' to my claim here than it might appear. "Conservation of information" is absolutely a thing in "the Standard Model", it is just that the information becomes non-localized and (in the Everett interpretation) spread across timelines. But the information that was "you" (using the model that seems standard on LW that 'you' are a collection of organized data) should, in theory, persist indefinitely into the future. Many authors subscribe to the idea that information conservation is /more/ fundamental than 'the laws of physics as we know them' and said information should then even survive transitions like symmetry breaking events, aka 'changes in the laws of physics' that might happen.

Now, whether that distributed information is 'experiencing' anything is arguable, but I can tell you that it is a theorem in quantum mechanics that physical information channels are in some sense symmetrical (again, there are variations which I think might be true that espouse breaks in this symmetry - but not in standard QM). This means you can't say (in quantum information theory) "Collection of information A learns about collection of information B, but not vice versa", only "Collections of information A and B become more entangled, in a quantifiable way". So if you lean calculus or classical physics or alchemy or biblical chronology from readings derived from the collection of information called "Sir Isaac Newton", then, if standard QM is valid, the collection of information called "Sir Isaac Newton" learns just as much about you, in real time!

Maybe Isaac Newton doesn't /need/ a meat body any more; he's uploaded as a continuous process into what David Bohm calls "the holomovement" and he influences the world every day, ask any freshman physics student about their homework problems and you'll see his influence in action.

Note this is not mysticism or nonsense, this is Vanilla Quantum Mechanics. I'm not claiming that the current collection of information we call "Sir Isaac Newton" is experiencing a mode of consciousness like that of a meat human right now, but rather that the collection still exists and is interacting with the world at large, becoming more entangled with some collections and less entangled (by some measure) with others, even as the Newtonsphere, current around 371 light years in radius, continues to expand.

Note that the Gentle Reader of this piece might be a human, or an AI, or a Searles Chinese Room type entity, or something else. If you are a living meat human reading this (or a sim that thinks it's a living meat human) you likely have some 'memories' pertaining to 'coming into existence' that date back less than two centuries. Unless you are like the author of this comment, you might not identify very hard with your 350-year-ago 'self', a collapsing 'incoming' wave of information that will eventually converge on your meat body and in some sense, supervise its construction and operation. There is no obligation to do so, and I predict with a moderate degree of confidence that people will consider you rather odd if you say things like "I am an immortal pattern of information in configuration space" but, to physicists of the 'timeless physics' school, that is pretty much what you appear to be. (I myself am happy to accept whatever self-definition you care to advertise to the world, so if you say "I am a human who did not exist before Month Day, Birthyear (or if RC, ConceptionYear)" I'm happy to accept that and say "This person is from a universe where the timeless formulation of quantum mechanics does not apply. How interesting." rather than "This entity's self-narrative is at variance with my very limited understanding of actual physics, so therefore THEY MUST BE CONFUSED, DELUDED, OR LYING and MY LIMITED KNOWLEDGE OF PHYSICS proves them to be so".

So.. as a Standard Physical Human Body Expressed As A Process In Time. cessation of existence not only doesn't scare me, it intrigues me, what would it be like to have that option? I have no idea how I would halt my evolution in the Schrodinger picture, or change my state vector in the Heisenberg (i.e. more or less timeless) picture.

I don't really believe that standard QM is 100 percent correct, it seems unlikely that what I was taught in grad school is the Correct Final Theory (I think 'nothing' is the most likely CFT actually, like asking "What is the last integer?" (spoiler: it's -1) because "there isn't one". However the usual thing to do on LW is to accept the current 'best known model of the laws of physics" as "tentatively true unless you're explicitly speculating about fringe theories or future developments" and so I post this offering as "my understanding of what the best current consensus among physicists tells us about Cessation of Existence".

Another time, if there is interest, I will discuss where new information seems to come from in a (multi? uni?)-verse where information is conserved, but that would be rambling.

That all being said, Cessation of Existence still does scare me and I want to avoid it, even if the best current physics indicates that it is actually impossible :) I'm also afraid of dragons materializing and challenging me to the Duel Draconic, which is almost equally improbable, but not quite impossible. (A quantum fluctuation of very low but distinctly non-zero probability could manifest as a draconic duelist gunning for me in my sensorium, according to standard QM, while the event described by "The Universe loses the collection of information that constitutes a given individual" has exactly zero probability, as it violates the premises of the system by which we calculate probabilities.