This is a really interesting point! If the universe is big enough that any concievable computer program exists somewhere, and all conscious experience can be represented as a classical computer program, then yes, under what I’m calling the “Ignore Copies” view, nothing would matter. Nick Bostrom makes this point in the “Quantity of experience” paper I referenced (I think it’s an important reason why he doesn’t like the “Ignore Copies” view).
But I don’t think MWI on its own necessarily predicts that the universe is this big. In fact, I’m fairly sure that it doesn’t (why would it? Edit: Now think Donald is right here and I was wrong) So I think in principle someone could accept both Ignore-Copies and MWI without being committed to the view that nothing matters.
In any case, I think this point is essentially independent of the point I’m trying to make in this post, which is just that there is a tension between the logic underpinning the “Ignore Copies” ethical view, and the supposed origin of probabilities in MWI.
But I don’t think MWI on its own necessarily predicts that the universe is this big.
I think this does, and it’s overdetermined.
Take a decently big computer. Make a program for it by generating a few gigs of random noise, using a quantum randomness source. Run the program. Now all possible computations (that fit on your computer) exist.
Another way of thinking about it.
“There exists a branch of the multiverse where X happens” is equivalent to ” an omniscient superintelligence that wanted to cause X to happen and gets to choose which branch to go down could make X happen”
So, what powers does this hypothetical omniscient superintelligence have. The ability to control all quantum randomness devices. Sure. But not just that. The ability to control every radioactive atom, when it decays and which way the radiation goes. The ability to control how hot objects radiate light, again to subatomic precision. Etc etc.
So, your taking a literally omnicient superintelligence, and giving it a bunch of powers that, while not quite omnipotence, are extremely overpowered. (And applies over the whole universe, since the big bang) And the task, build a reasonably decent computer and run a program on it, is not exactly hard.
(This conclusion might change under some versions of the mangled worlds hypothesis)
That’s a very strong argument, thanks! You’ve changed my mind! I hadn’t appreciated how big the multiverse in MWI could be, but that’s a good way to think about it.
In terms of what impact this has on my arguments here, I still think it doesn’t affect them, except that I now hope that Ignore-Copies and MWI are not both true at the same time. So in that sense I guess it’s a good thing that they seem to be in conflict with one another!
The mangled worlds hypothesis is also extremely interesting! I hadn’t come across it before, but as derivations of the Born rule go, this reads as the closest thing I’ve seen to the possible approach I was trying to describe at the end of my conclusion, where I speculated on what a derivation of the Born rule that did not clash with Ignore-Copies might look like. I’ll have to go and read Hanson’s papers on that. Thanks again! (may update the post to reference this)
(And if the mangled worlds derivation did turn out to be a way to reconcile Ignore-Copies with MWI, it’s also nice you think it might change the conclusion on nothing mattering as well, so that we still wouldn’t be forced to conclude that!)
This is a really interesting point! If the universe is big enough that any concievable computer program exists somewhere, and all conscious experience can be represented as a classical computer program, then yes, under what I’m calling the “Ignore Copies” view, nothing would matter. Nick Bostrom makes this point in the “Quantity of experience” paper I referenced (I think it’s an important reason why he doesn’t like the “Ignore Copies” view).
But I don’t think MWI on its own necessarily predicts that the universe is this big. In fact, I’m fairly sure that it doesn’t (why would it? Edit: Now think Donald is right here and I was wrong) So I think in principle someone could accept both Ignore-Copies and MWI without being committed to the view that nothing matters.
In any case, I think this point is essentially independent of the point I’m trying to make in this post, which is just that there is a tension between the logic underpinning the “Ignore Copies” ethical view, and the supposed origin of probabilities in MWI.
I think this does, and it’s overdetermined.
Take a decently big computer. Make a program for it by generating a few gigs of random noise, using a quantum randomness source. Run the program. Now all possible computations (that fit on your computer) exist.
Another way of thinking about it.
“There exists a branch of the multiverse where X happens” is equivalent to ” an omniscient superintelligence that wanted to cause X to happen and gets to choose which branch to go down could make X happen”
So, what powers does this hypothetical omniscient superintelligence have. The ability to control all quantum randomness devices. Sure. But not just that. The ability to control every radioactive atom, when it decays and which way the radiation goes. The ability to control how hot objects radiate light, again to subatomic precision. Etc etc.
So, your taking a literally omnicient superintelligence, and giving it a bunch of powers that, while not quite omnipotence, are extremely overpowered. (And applies over the whole universe, since the big bang) And the task, build a reasonably decent computer and run a program on it, is not exactly hard.
(This conclusion might change under some versions of the mangled worlds hypothesis)
That’s a very strong argument, thanks! You’ve changed my mind! I hadn’t appreciated how big the multiverse in MWI could be, but that’s a good way to think about it.
In terms of what impact this has on my arguments here, I still think it doesn’t affect them, except that I now hope that Ignore-Copies and MWI are not both true at the same time. So in that sense I guess it’s a good thing that they seem to be in conflict with one another!
The mangled worlds hypothesis is also extremely interesting! I hadn’t come across it before, but as derivations of the Born rule go, this reads as the closest thing I’ve seen to the possible approach I was trying to describe at the end of my conclusion, where I speculated on what a derivation of the Born rule that did not clash with Ignore-Copies might look like. I’ll have to go and read Hanson’s papers on that. Thanks again! (may update the post to reference this)
(And if the mangled worlds derivation did turn out to be a way to reconcile Ignore-Copies with MWI, it’s also nice you think it might change the conclusion on nothing mattering as well, so that we still wouldn’t be forced to conclude that!)