Epistemic status:
Here is the original post. Due to learning other people have discovered this independently and other encouraging comments below, I actually believe this idea may be very important, and needs to be corrected and expanded in several ways, and so I will likely create a new updated version later.
While I believe this idea’s consequences could be profound if correct, and it should be taken slightly more seriously than April Fool’s post “Ultra-Near-Termism”, I consider it mostly a quirky novelty, I’ve spent relatively little time thinking about it and suspect it may have major flaws. At the very least, I would hate for it to be taken too seriously before more serious investigation, and would really appreciate anyone pointing out flaws in reasoning that would clearly invalidate it!
TL;DR
If we give the prominent “eternal inflation theory” of cosmology and "evidential decision theory" a non-zero credence, then what is morally important may be what we are able to influence in the smallest unit of affectable time in the future. This would have a lot of weird implications, but it seems there are reasonable, if also weird, arguments that may defeat it.
Eternal Inflation and the Youngness Paradox
In this video, between video start and 11:40, Matt O'Dowd explains Alan Guth's "Youngness Paradox," that in each second, due to "Eternal Inflation", a leading cosmological theory, every second another 10^10^34 universes are born MORE than were born in the previous second, etc., eternally, meaning that every second the number of universes increases by a factor of 10^10^34 from how many existed in the previous second.
Based on a comment below, to be clear, this is different from quantum multiverse splitting, as this splitting happens at the moment of the Big Bang itself, causing the Big Bang to occur, essentially causing new, distinct bubble universes to form which are completely physically separate from each other, with it being impossible to causally influence any of the younger universes using any known physics as far as I am aware. Essentially, these are two different levels of the four level multiverse proposed by Max Tegmark.
Evidential Ultimate Neartermism
Anthropically/evidentially, this means that at any point in time, the sum of all younger universes carry exponentially far more weight than older universes, and almost all intelligent life that exists is that which is youngest across all universes; therefore, if we are trying to maximize the amount of good across all universes, what we should evidentially care about is what is happening soonest in time across all universes, including our own, as the weight of what happens across all universes soonest in time is always mind-boggling-ly more weight-y and hence valuable than what happens later in time. This, If correct, swamps longtermist arguments by a very, very large factor, and does so in expectation even if we give this theory and evidential decision theory an absurdly low credence.
If we follow this line of argument, then what we should altruistically hope for is that in every universe, everyone in that universe is trying to do whatever they can to maximize value in the next smallest affectable unit of time, meaning that there is at least some possibility that the morally correct thing to do is to try to maximize value (most likely for yourself, as it seems difficult to affect others as rapidly) in the next ~millisecond, and to be doing this at all times, hence,"Ultimate Neartermism."
Possible escape routes and implications
To be clear, I think that the same arguments that I suggest defeat Pascal’s Mugging and actually support longtermism, may also defeat arguments against blindly accepting this idea. Namely, we should give a non-zero credence that we might eventually figure out how to create a perpetual motion machine, or other ways that we might create infinite value, such as if we accept a cyclic universe or Penrose's Conformal Cyclic Cosmology model, or various infinite multiverses or many other weird anthropic or highly speculative theoretical scenarios (although, I can't say for certain any of these aren't also subject to the same youngness paradoxes due to different sizes of infinity). Another weird possibility, for example, is that even if we give an absurdly low, but nonzero credence that we might be able to influence all of the younger universes being created by eternal inflation, then perhaps that is what we should actually try to pursue, increasing the goodness of the exponentially huge number of future younger universes.
It seems to me that we should give this theory at least some credence, but its consequences are bizarre enough and potentially horrible enough from other perspectives that it seems worth thinking about it carefully rather than blindly accepting it. Doing further research on the value, likelihood, and consequences of this idea would, of course, mean that we may be losing a factor of 10^10^34 orders of magnitude worth of value of the universe every second this research takes (unless this research is moment to moment the most intrinsically valuable thing we could do,) however, because this loss of value always continues, if the theory is correct, doing the research is still worth incalculably more than other courses of action if it leads us to discover the idea is correct and act on it from there on out.
Interestingly, from the viewpoint of ultimate neartermism itself, it is of comparatively infinitesimally little value researching how to maximize value in the next millisecond. You lose so much value by doing so, that even if you have a positive but practically nonexistent credence that you may increase your next millisecond value by a virtually negligible amount, this value exceeds the value of researching how to best increase next millisecond value by a factor many, many, many times the value difference between the value of this research compared to the entire value of the future of our universe.
In fact, according to this theory virtually 100% of the value of the eternal inflation level of the multiverse is determined by how valuable the very first instant of consciousness is on average across all universes. Everything after that initial moment has 10^10^34 less orders of magnitude value every second that passes. Let’s hope that the very first spark of consciousness is a happy one!
That may make you feel like your impact is very small, since we are this late in the universe, and the entire sum of all moments across all older universes in the entire multiverse is always approximately 10^10^34 times less valuable than the first sparks of consciousness appearing in the very youngest universes in which consciousness is appearing in just this moment (of course, in the next moment those sparks of consciousness are old news and become just as approximately irrelevant as the rest of the older multiverse.)
However, you can take some comfort in the fact that the amount of impact you are having must be at least infinite, in expectation, since the “eternal” in “eternal inflation”, if I understand correctly, implies that the eternal inflation level of the multiverse is eternally expanding and never stops. It’s just that there are different sizes of infinity, and the amount of infinite impact you are having is much, much smaller than the total infinite impact occurring; and in a sense what really matters is the ratio of infinite impact between all universes (see: averagism.)
One of the most bizarre consequences of this idea is that it is extremely anti-memetic, i.e., if you accept it and are altruistic, then immediately you should start trying to maximize value in the following millisecond and continue doing so as long as you are able, which means you should put zero effort into spreading this theory, as plans that far in the future have virtually zero value compared to the evidential impact beings like you will have in the proceeding millisecond. Due to this fact, and the unappealing nature of this idea, it seems unlikely it will catch on, unfortunately even if correct.
to paraphrase what i think you mean: "new universes are eternally coming into existence at an exponentially increasing rate, and where no universes can be causally influenced by actions in other ones". in that case:
i don't see where this implies ultimate-neartermism. below i'll write where i think your reasoning went wrong, if i understood it correctly. (edit: i read hans' post, and i now see that you indeed meant something different!. i'll leave the below as an archive.)
i could have misinterpreted this somehow, but it seems like a mistake mainly of this form:
(2) is invalid, because it has not been established that statement A is true of set Z, only that it's true of set Y.
Applying this to the quote:
(my original natural language phrasing: though there are vastly more younger [later] universes, this does not imply younger [later] points in time within a single universe's time are quantitatively more than those at earlier points.)
i think these are both orthogonal to your argument for 'ultimate neartermism'.
for acausal trade considerations, just model the portions of different utility across worlds and make the trade accordingly.
though, new universes coming into existence 'eternally' (and at a non-diminishing rate) implies an infinite amount. possible values respond differently to this.
for some, which care about quantity, they will always be maxxed out along all dimensions due to infinite quantity* - at least, unless something they care about occurs with exactly 0% frequency - which could, i think, be influenced by portional acausal trade in certain logically-possible circumstances. (i.e maybe not possible for 'actual reality', but possible at least in some mathematical universes)
other utility functions might care about portion - that is, portion of / frequency within the infinite amount of worlds - rather than quantity. (e.g., i think my altruism still cares about this, though it's really tragic that there's infinite suffering). these ones acausal trade with each other.
* actually, that's not necessarily true. it can be reasoned that the amount is never actually infinite, only exponentially large, no matter how long it continues (2^x never does reach infinity), in which case at any actual point in time, quantity can still be increased / decreased.
(also, a slightly different statement A is used in (2): about moments rather than universes)
it seems to me that another understandable language mistake was made: a 'younger universe' (i.e a universe which begun to exist after already-existing (older) ones) sounds like it would, when translated to a single universe, mean 'an earlier point in time within that universe'; after all, a universe where less time has passed is younger. but 'younger' actually meant 'occurs later', in that context, plus we're now discussing moments rather than universes.