This post was completely rewritten on July 17th, 2015, 6:10 AM. Comments before that are not necessarily relevant.
Assume that our minds really do work the way Unification tells us: what we are experiencing is actually the sum total of every possible universe which produces them. Some universes have more 'measure' than others, and that is typically the stable ones; we do not experience chaos. I think this makes a great deal of sense- if our minds really are patterns of information I do not see why a physical world should have a monopoly on it.
Now to prove that we live in a Big World. The logic is simple- why would something finite exist? If we're going to reason that some fundamental law causes everything to exist, I don't see why that law restricts itself to this universe and nothing else. Why would it stop? It is, arguably, simply the nature of things for an infinite multiverse to exist.
I'm pretty terrible at math, so please try to forgive me if this sounds wrong. Take the 'density' of physical universes where you exist- the measure, if you will- and call it j. Then take the measure of universes where you are simulated and call it p. So, the question become is j greater than p? You might be thinking yes, but remember that it doesn't only have to be one simulation per universe. According to our Big World model there is a universe out there in which all processing power (or a significant portion) as been turned into simulations of you.
So we take the amount of minds being simulated per universe and call that x. Then the real question becomes if j > px. What sort of universe is common enough and contains enough minds to overcome j? If you say that approximately 10^60 simulated human minds could fit in it (a reasonable guess for this universe) but that such universes are five trillion times rarer than the universe we live in, than it's clear that our own 'physical' measure is hopelessly lower than our simulated measure.
Should we worry about this? It would seem highly probable that in most universes where I am being simulated I once existed in, or humans did, since the odds of randomly stumbling upon me in Mind Space seem unlikely enough to ignore. Presumably they are either AIs gone wrong or someone trying to grab some of my measure, for whatever reason.
As way of protecting measure, pretty much all of our postsingularity universes would divide up the matter of the universe for each person living, create as many simulations as possible of them from birth, and allow them to go through the Singularity. I expect that my ultimate form is a single me, not knowing if he is simulated or not, with billions of perfect simulations of himself across our universe, all reasoning the same way (he would be told this by the AI, since there isn't any more reason for secrecy). This, I think, would be able to guard my measure against nefarious or bizarre universes in which I am simulated. It cannot just simulate the last few moments of my life because those other universes might try to grab younger versions of me. So if we take j to be safe measure rather than physical measure, and p to be unsafe or alien, it becomes jx > px, which I think is quite reasonable.
I do not think of this as some kind of solipsist nightmare; the whole point of this is to simulate the 'real' you, the one that really existed, and part of your measure is, after all, always interacting in a real universe. I would suggest that by any philosophical standard the simulations could be ignored, with the value of your life being the same as ever.
Oh god I still can't get this thought out of my head. Can someone please tell me what they think of my solution to the problem?
I just read 'The Finale of the Ultimate Meta Mega Crossover' again. Is there a motivation for entities with unlimited computing power to simulate all possible programs in order? Or to take an interest in beings like me? Would that be enough to remove most of my measure from 'real' universes? I think probably not, but I need to be sure. I'm not thinking too clearly now.
EDIT: Wait a minute, this becomes more plausible after realizing someone out there in some universe has unlimited computing power. If so, could it affect measure? Or does only the density of the 'unlimited' universe itself affect measure? Please answer.
EDIT2: Max Tegmark argues that actual infinite quantities are not possible, because otherwise this causes trouble in the 'mathematical universe' model (only Gödel-complete mathematical structures can exist). If true, does this solve the problem? There may be universes with arbitrary amounts of computing power, but they still need to be optimized. Would the occasional intelligences that want to simulate humanlike beings overcome the measure of actually-existing universes like this one? Most such intelligences would want to simulate only the last few instants of life, but some (however rare) are certain to simulate the whole. And if they created billions of identical copies of me, would that increase measure as well?
The question is basically now: does the measure of my actual existence overcome the measure of worlds where I am simulated, even taking into account potentially limitless resources available to simulate?
I'm less panicked by this thought now, since if they are after my measure they must, in effect, simulate me exactly as I would really exist (taking into account the vertiginous question). So that part of my measure does not matter and I can value the part that really does correspond to an external reality.
Either way, if any of this is true (even with those that just simulate the last few instants of life) than an afterlife really does exist for everyone, regardless of quantum immortality.
EDIT3: OK, I think I've hit on a solution, but it'll take a while to type up.
By the gods, this is getting serious. Ladies and gentlemen, I give you Eitan's Basilisk.
You need a reality check:
You're building a theory of reality from fictional evidence. Even if the underlying theory exists in real life, the author's narrative choices introduce a tremendous bias. Browsing through LW's earlier material will show you why that doesn't work.
Apparently, you believe your mind creates reality. That's simply not true, as I was very much alive before I knew you existed. Of course, I have no way of definitely proving my previous subjective e