Epiphenominal theories of consciousness are kind of silly, but here’s another situation I can wonder about… some cellular automata rules, including the Turing-complete Conway’s Game of Life, can have different “pasts” that can lead to the same present. From the point of view of a being living in such a universe (one in which information can be destroyed), is there a fact of the matter as to which “past” actually happened?
I had always thought that our physical universe had this property as well, i.e. the Everett multiverse branches into the past as well as into the future.
If you take a single branch and run it backward, you’ll find that it diverges into a multiverse of its own. If you take all the branches and run them backward, their branches will cohere instead of decohering, cancel out in most places, and miraculously produce only the larger, more coherent blobs of amplitude they started from. Sort of like watching an egg unscramble itself.
If you take all the branches and run them backward, their branches will cohere instead of decohering, cancel out in most places, and miraculously produce only the larger, more coherent blobs of amplitude they started from.
And the beings in them will only have memories of further-cohered (further “pastward”) events, just as if you didn’t run anything backwards.
And at the beginning of the universe we have a set of states which just point time-backwards at each other, which is why we cannot go meaningfully more backwards in time.
Something like: A1 goes with probability 1% to B1, 1% to C1, and 98% to A2. B1 goes with probability 1% to A1, 1% to C1, and 98% to B2. C1 goes with probability 1% to A1, 1% to B1, and 98% to C2.
So if you ask about the past of A2, you get A1, which is the part that makes intuitive sense for us. But trying to go deeper in the past just gives us that the past of A1 is B1 or C1, and the past of B1 is A1 or C1, etc. Except that the change does not clearly happen in one moment (A2 has a rather well-defined past, A1 does not), but more gradually.
I don’t think anyone takes seriously the way standard physics models the beginning of time (temperature and density of the universe approaching infinity as its age approaches zero), anyway, as it’s most likely incorrect due to quantum gravity effects.
I don’t think anyone takes seriously the way standard physics models the beginning of time (temperature and density of the universe approaching infinity
This is a correct usage of terminology but the irony still made me smile.
Oh. I tried to find something, but the only thing that partially pattern-matches it was the Hartle–Hawking state. If we mix it with the “universe as a Markov chain over particle configurations” model, it could lead to something like this. Or could not.
Interesting question! I’d say that you could refer to the possibilities as possibilities, e.g. in a debate over whether a particular past would in fact have led to the present, but to speak of the ‘actual past’ might make no sense because you couldn’t get there from there… no, actually, I take that back, you might be able to get there via simplicity. I.e. if there’s only one past that would have evolved from a simply-tiled start state for the automaton.
But does it really matter? If both states are possible, why not just say “my past contains ambiguity?”
With quantum mechanics, even though the “future” itself (as a unified wavefunction) evolves forward as a whole, the bit-that-makes-up-this-pseudofactor-of-me has multiple possible outcomes. We live with future ambiguity just fine, and quantum mechanics forces us to say “both experienced futures must be dealt with probabilistically”. Even though the mechanism is different, what’s wrong with treating the “past” as containing the same level of branching as the future?
EDIT: From a purely global, causal perspective, I understand the desire to be able to say, “both X and Y can directly cause Z, but in point of fact, this time it was Y.” But you’re inside, so you don’t get to operate as a thing that can distinguish between X and Y, and this isn’t necessarily an “orbital teapot” level of implausibility. If configuration Y is 10^4 more likely as a ‘starting’ configuration than configuration X according to your understanding of how starting configurations are chosen, then sure—go ahead and assert that it was (or may-as-well-have-been) configuration Y that was your “actual” past—but if the configuration probabilities are more like 70%/30%, or if your confidence that you understand how starting configurations are chosen is low enough, then it may be better to just swallow the ambiguity.
EDIT2: Coming from a completely different angle, why assert that one or the other “happened”, rather than looking at it as a kind of path-integral? It’s a celular automaton, instead of a quantum wave-function, which means that you’re summing discrete paths instead of integrating infinitesimals, but it seems (at first glance) that the reasoning is equally applicable.
If both states are possible, why not just say “my past contains ambiguity?”
Ambiguity it is, but we usually want to know the probabilities. If I tell you that whether you win or not win a lottery tomorrow is “ambiguous”, you would not be satisfied with such answer, and you would ask how much likely it is to win. And this question somehow makes sense even if the lottery is decided by a quantum event, so you know that each future happens in some Everett branch.
Similarly, in addition to knowing that the past is ambiguous, we should ask how likely are the individual pasts. In our universe you would want to know how the pasts P1 and P2 are likely to become NOW. The Conway’s Game of Life does not branch time-forward, so if you have two valid pasts, their probabilities of becoming NOW are 100% each.
But that is only a part of the equation. The other part are the prior probabilities of P1 and P2. Even if both P1 and P2 deterministically evolve to NOW, their prior probabilities influence how likely did NOW really evolve from each of them.
I am not sure what would be the equivalent of Solomonoff induction for the Conway’s Game of Life. Starting with a finite number of “on” cells, where each additional “on” cell decreases the prior probability of the configuration? Starting with an infinite plane where each cell has a 50% probability to be “on”? Or an infinite plane with each cell having a p probability of being “on”, where p has the property that after one step in such plane, the average ratio of “on” cells remain the same (the p being kind-of-eigenvalue of the rules)?
But the general idea is that if P1 is somehow “generally more likely to happen” than P2, we should consider P1 to be more likely the past of NOW than P2, even if both P1 and P2 deterministically evolve to NOW.
In the Game of Life, a single live cell with no neighbours will become a dead cell in the next step. Therefore, any possible present state that has at least one past state has an infinite number of one-step-back states (which differ from the one state merely in having one or more neighbourless cells at random locations, far enough from anything else to have no effect).
Some of these one-step-back states may end up having evolved from simpler starting tilesets than the one with no vanishing cells.
no, actually, I take that back, you might be able to get there via simplicity. I.e. if there’s only one past that would have evolved from a simply-tiled start state for the automaton.
The simplest start state might actually be a program that simulates the evolution of every possible starting state in parallel. If time and space are unbounded and an entity is more complex than the shortest such program then it is more likely that the entity is the result of the program and not the result of evolving from another random state.
I am unable to see the appeal of a view in which there is no fact of the matter. It seems to me that there is a fact of the matter concerning the past, even if it is impossible for us to know. This is not similar to the case where sneezing alters two shadow variables, and it is impossible for us to meaningfully refer to variable 1 as opposed to variable 2; the past has a structure, so assertions will typically have definite referents.
The Standard Model of particle physics with MWI is time-symmetric (to be precise: CPT symmetric) and conserves information. If you define the precise state at one point in time, you can calculate the unique past which lead to that state and the unique future which will evolve from that state. Note that for general states, “past” and “future” are arbitrary definitions.
This is actually one of the reasons I have to doubt Cryonics. You can talk about nano-tech being able to “reverse” the damage, but it’s possible (and I think likely), that it’s very hard to go from damaged states to the specific non-damaged state that actually constitutes your consciousness/memory.
Assuming that “you” are a point in consciousness phase-space, and not a “smear”. If “you-ness” is a locus of similar-but-slightly-different potential states, then “mostly right” is going to be good enough.
And, given that every morning when you wake up, you’re different-but-still-you, I’d say that there’s strong evidence that “you-ness” is a locus of similar-but-slightly-different potential states, rather than a singular point.
This means, incidentally, that it may be possible to resurrect people without a physical copy of their brains at all, if enough people who remember them well enough when the technology becomes available.
Of course, since it’s a smear, the question becomes “where do you want to draw the line between Bob and not-Bob?”—since whatever you create will believe it’s Bob, and will act the way everyone alive remembers that Bob acted, and the “original” isn’t around to argue (assuming you believe in concepts like “original” to begin with, but if you do, you have some weirder paradoxes to deal with).
Which is why it’s better for there to be more people signed up, but not actually being frozen yet. The more money they get while the later you get frozen, the better the odds. If immortality is something you want, this still seems like the best gamble.
In that particular case, “never happened” has some weird ontological baggage. If a simulated consciousness is still conscious, then isn’t its simulated past still a past?
Perhaps “didn’t happen” in the sense that its future reality will not conform to its memory-informed expectations, but it seems like, if those memories form a coherent ‘past’, then in a simulationist sense that past did happen, even if it wasn’t simulated with perfect fidelity.
Epiphenominal theories of consciousness are kind of silly, but here’s another situation I can wonder about… some cellular automata rules, including the Turing-complete Conway’s Game of Life, can have different “pasts” that can lead to the same present. From the point of view of a being living in such a universe (one in which information can be destroyed), is there a fact of the matter as to which “past” actually happened?
I had always thought that our physical universe had this property as well, i.e. the Everett multiverse branches into the past as well as into the future.
If you take a single branch and run it backward, you’ll find that it diverges into a multiverse of its own. If you take all the branches and run them backward, their branches will cohere instead of decohering, cancel out in most places, and miraculously produce only the larger, more coherent blobs of amplitude they started from. Sort of like watching an egg unscramble itself.
And the beings in them will only have memories of further-cohered (further “pastward”) events, just as if you didn’t run anything backwards.
And at the beginning of the universe we have a set of states which just point time-backwards at each other, which is why we cannot go meaningfully more backwards in time.
Something like:
A1 goes with probability 1% to B1, 1% to C1, and 98% to A2.
B1 goes with probability 1% to A1, 1% to C1, and 98% to B2.
C1 goes with probability 1% to A1, 1% to B1, and 98% to C2.
So if you ask about the past of A2, you get A1, which is the part that makes intuitive sense for us. But trying to go deeper in the past just gives us that the past of A1 is B1 or C1, and the past of B1 is A1 or C1, etc. Except that the change does not clearly happen in one moment (A2 has a rather well-defined past, A1 does not), but more gradually.
As I understand it, this is not how standard physics models the beginning of time.
I don’t think anyone takes seriously the way standard physics models the beginning of time (temperature and density of the universe approaching infinity as its age approaches zero), anyway, as it’s most likely incorrect due to quantum gravity effects.
This is a correct usage of terminology but the irony still made me smile.
What?
I think wedrifid is pointing to the irony in saying that the ‘standard’ model is (on some issue) standardly rejected.
Oh. I tried to find something, but the only thing that partially pattern-matches it was the Hartle–Hawking state. If we mix it with the “universe as a Markov chain over particle configurations” model, it could lead to something like this. Or could not.
Interesting question! I’d say that you could refer to the possibilities as possibilities, e.g. in a debate over whether a particular past would in fact have led to the present, but to speak of the ‘actual past’ might make no sense because you couldn’t get there from there… no, actually, I take that back, you might be able to get there via simplicity. I.e. if there’s only one past that would have evolved from a simply-tiled start state for the automaton.
But does it really matter? If both states are possible, why not just say “my past contains ambiguity?”
With quantum mechanics, even though the “future” itself (as a unified wavefunction) evolves forward as a whole, the bit-that-makes-up-this-pseudofactor-of-me has multiple possible outcomes. We live with future ambiguity just fine, and quantum mechanics forces us to say “both experienced futures must be dealt with probabilistically”. Even though the mechanism is different, what’s wrong with treating the “past” as containing the same level of branching as the future?
EDIT: From a purely global, causal perspective, I understand the desire to be able to say, “both X and Y can directly cause Z, but in point of fact, this time it was Y.” But you’re inside, so you don’t get to operate as a thing that can distinguish between X and Y, and this isn’t necessarily an “orbital teapot” level of implausibility. If configuration Y is 10^4 more likely as a ‘starting’ configuration than configuration X according to your understanding of how starting configurations are chosen, then sure—go ahead and assert that it was (or may-as-well-have-been) configuration Y that was your “actual” past—but if the configuration probabilities are more like 70%/30%, or if your confidence that you understand how starting configurations are chosen is low enough, then it may be better to just swallow the ambiguity.
EDIT2: Coming from a completely different angle, why assert that one or the other “happened”, rather than looking at it as a kind of path-integral? It’s a celular automaton, instead of a quantum wave-function, which means that you’re summing discrete paths instead of integrating infinitesimals, but it seems (at first glance) that the reasoning is equally applicable.
Ambiguity it is, but we usually want to know the probabilities. If I tell you that whether you win or not win a lottery tomorrow is “ambiguous”, you would not be satisfied with such answer, and you would ask how much likely it is to win. And this question somehow makes sense even if the lottery is decided by a quantum event, so you know that each future happens in some Everett branch.
Similarly, in addition to knowing that the past is ambiguous, we should ask how likely are the individual pasts. In our universe you would want to know how the pasts P1 and P2 are likely to become NOW. The Conway’s Game of Life does not branch time-forward, so if you have two valid pasts, their probabilities of becoming NOW are 100% each.
But that is only a part of the equation. The other part are the prior probabilities of P1 and P2. Even if both P1 and P2 deterministically evolve to NOW, their prior probabilities influence how likely did NOW really evolve from each of them.
I am not sure what would be the equivalent of Solomonoff induction for the Conway’s Game of Life. Starting with a finite number of “on” cells, where each additional “on” cell decreases the prior probability of the configuration? Starting with an infinite plane where each cell has a 50% probability to be “on”? Or an infinite plane with each cell having a p probability of being “on”, where p has the property that after one step in such plane, the average ratio of “on” cells remain the same (the p being kind-of-eigenvalue of the rules)?
But the general idea is that if P1 is somehow “generally more likely to happen” than P2, we should consider P1 to be more likely the past of NOW than P2, even if both P1 and P2 deterministically evolve to NOW.
In the Game of Life, a single live cell with no neighbours will become a dead cell in the next step. Therefore, any possible present state that has at least one past state has an infinite number of one-step-back states (which differ from the one state merely in having one or more neighbourless cells at random locations, far enough from anything else to have no effect).
Some of these one-step-back states may end up having evolved from simpler starting tilesets than the one with no vanishing cells.
The simplest start state might actually be a program that simulates the evolution of every possible starting state in parallel. If time and space are unbounded and an entity is more complex than the shortest such program then it is more likely that the entity is the result of the program and not the result of evolving from another random state.
I am unable to see the appeal of a view in which there is no fact of the matter. It seems to me that there is a fact of the matter concerning the past, even if it is impossible for us to know. This is not similar to the case where sneezing alters two shadow variables, and it is impossible for us to meaningfully refer to variable 1 as opposed to variable 2; the past has a structure, so assertions will typically have definite referents.
The Standard Model of particle physics with MWI is time-symmetric (to be precise: CPT symmetric) and conserves information. If you define the precise state at one point in time, you can calculate the unique past which lead to that state and the unique future which will evolve from that state. Note that for general states, “past” and “future” are arbitrary definitions.
(Which is why I specified a different set of laws of physics.)
This is actually one of the reasons I have to doubt Cryonics. You can talk about nano-tech being able to “reverse” the damage, but it’s possible (and I think likely), that it’s very hard to go from damaged states to the specific non-damaged state that actually constitutes your consciousness/memory.
Assuming that “you” are a point in consciousness phase-space, and not a “smear”. If “you-ness” is a locus of similar-but-slightly-different potential states, then “mostly right” is going to be good enough.
And, given that every morning when you wake up, you’re different-but-still-you, I’d say that there’s strong evidence that “you-ness” is a locus of similar-but-slightly-different potential states, rather than a singular point.
This means, incidentally, that it may be possible to resurrect people without a physical copy of their brains at all, if enough people who remember them well enough when the technology becomes available.
Of course, since it’s a smear, the question becomes “where do you want to draw the line between Bob and not-Bob?”—since whatever you create will believe it’s Bob, and will act the way everyone alive remembers that Bob acted, and the “original” isn’t around to argue (assuming you believe in concepts like “original” to begin with, but if you do, you have some weirder paradoxes to deal with).
Which is why it’s better for there to be more people signed up, but not actually being frozen yet. The more money they get while the later you get frozen, the better the odds. If immortality is something you want, this still seems like the best gamble.
Or, a Boltzmann brain that flickered into existence with memories of a past that never happened.
In that particular case, “never happened” has some weird ontological baggage. If a simulated consciousness is still conscious, then isn’t its simulated past still a past?
Perhaps “didn’t happen” in the sense that its future reality will not conform to its memory-informed expectations, but it seems like, if those memories form a coherent ‘past’, then in a simulationist sense that past did happen, even if it wasn’t simulated with perfect fidelity.