5 ms·

Thought experiment on the nature of reality: - In a much larger universe, write down in a log book every event to every particle at every instant, from the Big

Thought experiment on the nature of reality: - In a much larger universe, write down in a log book every event to every particle at every instant, from the Big Bang to the restaurant. - Put it on the fireplace mantle and leave it there. This is basically a log of a simulation. It exists in much the same way as an ongoing simulation would, except that its time dimension isn't shared with the simulating universe. But every observer within has had the same observations as if it did.

skissane 2y ago
This assumes that a map, if sufficiently detailed, is identical to the territory. Maybe it is, maybe it isn’t - but it is a highly debatable metaphysical assumption. I’m not sure how seriously we should take some people’s claims that they “know” that such an assumption is actually true
- worstspotgain 2y ago
  It's an argument about simulations, not about reality. If reality is a simulation, then arguments about simulations apply to it, but that's the big if.
  - mistermann 2y ago
    The word "simulation" is it self a simulation. So is the word "is". https://en.m.wikipedia.org/wiki/Semiotics https://en.m.wikipedia.org/wiki/Semiotics Reality is a multi-disciplinary domain, but it gives off the appearance of being physics only, because of its metaphysical nature.
  - skissane 2y ago
    Not necessarily. Suppose that consciousness/qualia/etc is “something extra” which has to be added to non-mental reality, as some dualists believe. Then, it would be possible that we live in a simulation which contains consciousness because that “something extra” has somehow been added to it. And yet, maybe the “much larger” universe which contains our simulation also contains such a “log book” of a very similar universe to our own, also containing intelligent life - and yet, if the “something extra” has not been added to that “log book”, it would lack consciousness and qualia, unlike our own universe. I’m not arguing that a dualism (of this sort) is actually true, merely that we don’t (and can’t) know for a fact that it is false. But if we can’t know for a fact that it is false, then even if we (somehow) knew our reality was simulated, that wouldn’t give us grounds to make confident inferences about the nature of other simulations, or the nature of simulations in themselves
    - worstspotgain 2y ago
      I agree with your post. However, I was using the most mechanical meaning of simulation: "the production of a computer model of something, especially for the purpose of study," which implies determinism and excludes the "something extra."
      - skissane 2y ago
        It doesn’t actually exclude the “something extra”, it is neutral as to whether or not there is any “something extra” Panpsychists claim everything is conscious, even rocks, even atoms. Again, I don’t claim this is true (I’d be rather shocked if I somehow found out it was), but we can’t know for a fact that it is false. Yet if panpsychism (or at least certain versions thereof) is true, every simulation (even a simulation of the weather, or of crop growth) is conscious, simply because absolutely everything is. But I don’t think most standard definitions of “simulation” are excluding that possibility - on the contrary, they are agnostic with respect to it, treating its truth or falsehood as outside of their scope It also doesn’t necessarily imply determinism because some computer simulations use RNGs. Most commonly people use pseudorandom RNGs for this, but there is nothing in principle stopping someone from replacing the pseudorandom RNG with a hardware RNG based on some quantum mechanical process, such that it is indeterministic for all practical purposes, and the question of whether it is ultimately deterministic or indeterministic depends on controversial questions about QM to which nobody knows the answers
        worstspotgain 2y ago
        > It doesn’t actually exclude the “something extra”, it is neutral as to whether or not there is any “something extra” Roger, that's even better. I tried to clarify the log book idea in another reply.[1] The question is whether you can have reality (from the observer's perspective) just based on whether coherent information exists in any setting. Basically the question is whether we can go from "I think, therefore I am" to "something is constructing information." The latter is obviously a simpler, lower-level proof than other concepts of existence. That brings us back to the "something extra." Is it required for our observations to be possible, i.e. can we rule out the log book conjecture? I don't think we can, but I might be wrong. [1] https://news.ycombinator.com/item?id=41783599 https://news.ycombinator.com/item?id=41783599
- FrustratedMonky 2y ago
  Except for the randomness introduced in Quantum Mechanics. If they ever solve the randomness, then if the map is down to every particle, then yes, the map and reality could be the same. But think at that point you need a computer the size of reality to keep track of every particle. Or, maybe the entire universe is one giant wave equation. But again, I think you need a computer the size of the universe to solve it.
  - worstspotgain 2y ago
    Are you saying that some things are just not simulable, given a sufficiently large and powerful computer, or that the universe is or might be infinite?
    - FrustratedMonky 2y ago
      If the universe is real, not simulation. If you know the position and speed, everything, about every particle, then you should be able to extrapolate the future by calculating it. The problem is you need a computer the size of the universe to do that calculation. So even thought the map is the territory, equal scale, and you have the map. It is little worthless because the map ends up being reality. Edit: Little different than the idea that if this is simulation, you can do clipping and only render what we see. I'm saying the entire universe is 'real'.
      - tines 2y ago
        > If you know the position and speed, everything, about every particle, then you should be able to extrapolate the future by calculating it. But isn't that the exact thing that quantum mechanics refutes? You cannot know the future just from the past; you can only know the probabilities of different futures.
        FrustratedMonky 2y ago
        Yes. I referred to the randomness that would prevent this, "once that is solved". Guess I'm in the camp that eventually we'll find some model or discover something new, to discover what is behind the randomness, so it is no longer just random. But, yes, that is big IF. Until then, with current theories, we couldn't do these calculations. They'd just be approximations accounting for some randomness.
- partomniscient 2y ago
  I am King Ozymandias look upon my complete data dump/backup*, ye mighty and despair! *May be subject to entropy over time.
amelius 2y ago
If I took the binary representation of that log and XOR'ed it with a random binary string, then would the result also have observers with the same observations?
- worstspotgain 2y ago
  Good question? :) I'd say no. How about an exact copy of the log book, but with one bit flipped. Voila, mostly universal physics.
deleted 2y ago
[deleted]
kouru225 2y ago
Ok but the act of writing it down would always take longer than the actual unfolding of the universe itself. Just like the halting problem, we can’t skip ahead at any point and we have no idea what will come next.
- worstspotgain 2y ago
  Sure, but the timebases are different. Maybe it took the butterflypeople a thousand butterflyweeks to write it out. Let me restate the metaphysics a bit differently. Let's say there's no us, no butterflypeople, nothing at all. Entropy reigns supreme, no information is organized. Now add the butterflypeople. They write the humanpeople's log book. Information exists in organized form. The humanpeople's bits have been divined out of the great entropic nothing. Maybe that's all it takes?
  - garaetjjte 2y ago
    Reminds me of https://xkcd.com/505/ https://xkcd.com/505/
julianeon 2y ago
There's a hidden condition here. How do you know every event to every particle? The answer to that will literally change what gets written in the log book.
- kridsdale3 2y ago
  The point is the log is a graph or a tree, not an array.
throw310822 2y ago
Now shred that log to particles and scatter them everywhere, and you have the "dust theory". Neither the time dimension or the log are shared with the simulating universe, and yet they are still valid for the observers within the universe. If the sequence of the log states is entirely deterministic based on the initial state, then you don't even need to actually write down the entire log for it to "exist". This is Greg Egan's Permutation City.
- worstspotgain 2y ago
  Can we reduce this to an estimate of survivorship bias? If there is only one universe, then our survival is clearly explained: we're in the only reality there is. If all possible universes exist, then we really lucked out in ending up in this one (well, depending on who wins the election I guess.) In the middle are the permutations selected through the filter of other realities, when they chose which universes to simulate. We lucked out but not as much, because uninteresting universes never made it out of the entropic soup. It would have to be a conditional estimate of course, because our sentience biases our contemplation.
oersted 2y ago
Quick appreciation for the Douglas Adams reference :)
buginprod 2y ago
Randall has you covered: https://xkcd.com/505/ https://xkcd.com/505/
nonameiguess 2y ago
This kind of thought experiment seems like it breaks down due to the uncertainty principle. We can't exactly specify the full state of every particle in the universe. The universe might also be infinite and you can't enumerate an infinite set even without uncertainty, though you can write a generating function or recurrence relation for it, which seems to be Wolfram's point. But why bother with this kind of detail? What's the difference between what you're imagining here and a normal reel of film? It can be played back, but even if it isn't, it records the state of events that happened, including observers that once existed and no longer do, experiencing events that once happened but no longer do. It's possible for a record to describe a canonical sequence even if the record itself doesn't change. Somebody outside of the record can view it out of order, speed it up, slow it down, pause it, reverse it. A film reel doesn't share the time dimension of its own universe in that way. I'm struggling to come up with what this implies and why.
- worstspotgain 2y ago
  To your first point, if it's a simulated universe, the simulators can just choose to make it finite, and come up with their preferred particle behavior rules. As observers, we perceive time as passing, but is there anything special in this perception? Looked at another way, everything could be frozen in a 4D log book and we couldn't tell the difference, or could we? In this interpretation, Napoleon is as alive (in 1820) as we are (in 2024.) A film reel is a similar concept, except it's just a 3D projection rather than a complete detailed 4D account.
  - nonameiguess 2y ago
    I get the questions of eternalism, the reality of the past and future, why privilege the present (or at least my present), and all that. I just don't understand why the fact that you can record events in a medium that doesn't experience the time that it records has any implications for how we should think about this. Whether or not you want to say "Napoleon exists" or "Napoleon existed" seems to be a matter of linguistic convention and the more common latter would reflect speakers privileging their own time. If you want to look at it another way, Napoleon exists, but entirely in my past light cone, and I exist entirely in his future light cone. I can't send him any kind of information, but he can send information to me. Is there anything special in this perception? To who? To observers at the absolute end of all time, my future is just as written in stone as Napoleon's. To observers I can receive information from, my future is unknown. To any particular observer, there are regions of spacetime in which you have no past. There are regions in which you have no future. There is a region in which you have both a past and a future. Is there anything "special" in perceiving the sequence of events within the third region as passing rather than existing forever as a log? Not really. You're just describing a different variety of the Copernican principle or relativity as far as I can tell. But so what? None of us are the center of the univers. None of us exist in a special inertial frame describing absolute spacetime. These facts, however, have consequences in terms of how to measure and compute stuff. They change the kind of testable predictions you make given certain conditions. What computational or predictive consequences arise from observing that the entire world curve of the universe exists at once from a perspective outside of the universe? Going back to the I can't send information to Napoleon thing, if observers outside of our universe are keeping a log, none of us nor anything else in our universe can receive information from them, so what difference does it make? It's an interesting shower thought but kind of also a big so what?
jiggawatts 2y ago
A fun variant of this is that the log can be taken at variable intervals and as long as it is sufficiently detailed, it can still capture all salient details. Similarly a simulation run at some "tick rate" can also be run at 2x the rate while taking 1/2 the step per tick. Within the universe nobody would notice, as long as the steps were fine enough to begin with. I think it was in Diaspora (or Permutation City?) that Greg Egan proposed that any tick rate would be unnoticable to that simulated beings, including "none". In other words, the movie Top Gun will continue to exist as-is, no matter how many copies are made of it, including none. Encoded as a digital file it is just a number, a pure timeless concept, it doesn't have to be written down to exist. It always existed on the number line, even before Tom Cruise was born. In fact, every encoding of Top Gun exists on the number line, in every compression format, in every resolution, even a future 16K resolution that was never filmed and has no display devices made for it yet. Its encoding as a 400GB long number is there, already, and will always be there. In other words, and simulation, an log of events, any experience already exists in mathematics, in every encoding... somewhere on the number line. This includes the entire physical universe. This isn't hypothetical, it's necessarily true! Anything that can be represented by a finite amount of information must be on the number line. Even if you assume the Universe lasts forever, you can break its history up into a sequence of states, each of which is finite. Then the series will exists on the number line as a set of points heading off to infinity.

skissane 2y ago

This assumes that a map, if sufficiently detailed, is identical to the territory. Maybe it is, maybe it isn’t - but it is a highly debatable metaphysical assumption. I’m not sure how seriously we should take some people’s claims that they “know” that such an assumption is actually true

worstspotgain 2y ago
It's an argument about simulations, not about reality. If reality is a simulation, then arguments about simulations apply to it, but that's the big if.
- mistermann 2y ago
  The word "simulation" is it self a simulation. So is the word "is". https://en.m.wikipedia.org/wiki/Semiotics https://en.m.wikipedia.org/wiki/Semiotics Reality is a multi-disciplinary domain, but it gives off the appearance of being physics only, because of its metaphysical nature.
- skissane 2y ago
  Not necessarily. Suppose that consciousness/qualia/etc is “something extra” which has to be added to non-mental reality, as some dualists believe. Then, it would be possible that we live in a simulation which contains consciousness because that “something extra” has somehow been added to it. And yet, maybe the “much larger” universe which contains our simulation also contains such a “log book” of a very similar universe to our own, also containing intelligent life - and yet, if the “something extra” has not been added to that “log book”, it would lack consciousness and qualia, unlike our own universe. I’m not arguing that a dualism (of this sort) is actually true, merely that we don’t (and can’t) know for a fact that it is false. But if we can’t know for a fact that it is false, then even if we (somehow) knew our reality was simulated, that wouldn’t give us grounds to make confident inferences about the nature of other simulations, or the nature of simulations in themselves
  - worstspotgain 2y ago
    I agree with your post. However, I was using the most mechanical meaning of simulation: "the production of a computer model of something, especially for the purpose of study," which implies determinism and excludes the "something extra."
    - skissane 2y ago
      It doesn’t actually exclude the “something extra”, it is neutral as to whether or not there is any “something extra” Panpsychists claim everything is conscious, even rocks, even atoms. Again, I don’t claim this is true (I’d be rather shocked if I somehow found out it was), but we can’t know for a fact that it is false. Yet if panpsychism (or at least certain versions thereof) is true, every simulation (even a simulation of the weather, or of crop growth) is conscious, simply because absolutely everything is. But I don’t think most standard definitions of “simulation” are excluding that possibility - on the contrary, they are agnostic with respect to it, treating its truth or falsehood as outside of their scope It also doesn’t necessarily imply determinism because some computer simulations use RNGs. Most commonly people use pseudorandom RNGs for this, but there is nothing in principle stopping someone from replacing the pseudorandom RNG with a hardware RNG based on some quantum mechanical process, such that it is indeterministic for all practical purposes, and the question of whether it is ultimately deterministic or indeterministic depends on controversial questions about QM to which nobody knows the answers
      - worstspotgain 2y ago
        > It doesn’t actually exclude the “something extra”, it is neutral as to whether or not there is any “something extra” Roger, that's even better. I tried to clarify the log book idea in another reply.[1] The question is whether you can have reality (from the observer's perspective) just based on whether coherent information exists in any setting. Basically the question is whether we can go from "I think, therefore I am" to "something is constructing information." The latter is obviously a simpler, lower-level proof than other concepts of existence. That brings us back to the "something extra." Is it required for our observations to be possible, i.e. can we rule out the log book conjecture? I don't think we can, but I might be wrong. [1] https://news.ycombinator.com/item?id=41783599 https://news.ycombinator.com/item?id=41783599
FrustratedMonky 2y ago
Except for the randomness introduced in Quantum Mechanics. If they ever solve the randomness, then if the map is down to every particle, then yes, the map and reality could be the same. But think at that point you need a computer the size of reality to keep track of every particle. Or, maybe the entire universe is one giant wave equation. But again, I think you need a computer the size of the universe to solve it.
- worstspotgain 2y ago
  Are you saying that some things are just not simulable, given a sufficiently large and powerful computer, or that the universe is or might be infinite?
  - FrustratedMonky 2y ago
    If the universe is real, not simulation. If you know the position and speed, everything, about every particle, then you should be able to extrapolate the future by calculating it. The problem is you need a computer the size of the universe to do that calculation. So even thought the map is the territory, equal scale, and you have the map. It is little worthless because the map ends up being reality. Edit: Little different than the idea that if this is simulation, you can do clipping and only render what we see. I'm saying the entire universe is 'real'.
    - tines 2y ago
      > If you know the position and speed, everything, about every particle, then you should be able to extrapolate the future by calculating it. But isn't that the exact thing that quantum mechanics refutes? You cannot know the future just from the past; you can only know the probabilities of different futures.
      - FrustratedMonky 2y ago
        Yes. I referred to the randomness that would prevent this, "once that is solved". Guess I'm in the camp that eventually we'll find some model or discover something new, to discover what is behind the randomness, so it is no longer just random. But, yes, that is big IF. Until then, with current theories, we couldn't do these calculations. They'd just be approximations accounting for some randomness.
partomniscient 2y ago
I am King Ozymandias look upon my complete data dump/backup*, ye mighty and despair! *May be subject to entropy over time.

amelius 2y ago

If I took the binary representation of that log and XOR'ed it with a random binary string, then would the result also have observers with the same observations?

worstspotgain 2y ago
Good question? :) I'd say no. How about an exact copy of the log book, but with one bit flipped. Voila, mostly universal physics.

deleted 2y ago

[deleted]

kouru225 2y ago

Ok but the act of writing it down would always take longer than the actual unfolding of the universe itself. Just like the halting problem, we can’t skip ahead at any point and we have no idea what will come next.

worstspotgain 2y ago
Sure, but the timebases are different. Maybe it took the butterflypeople a thousand butterflyweeks to write it out. Let me restate the metaphysics a bit differently. Let's say there's no us, no butterflypeople, nothing at all. Entropy reigns supreme, no information is organized. Now add the butterflypeople. They write the humanpeople's log book. Information exists in organized form. The humanpeople's bits have been divined out of the great entropic nothing. Maybe that's all it takes?
- garaetjjte 2y ago
  Reminds me of https://xkcd.com/505/ https://xkcd.com/505/

julianeon 2y ago

There's a hidden condition here. How do you know every event to every particle? The answer to that will literally change what gets written in the log book.

kridsdale3 2y ago
The point is the log is a graph or a tree, not an array.

throw310822 2y ago

Now shred that log to particles and scatter them everywhere, and you have the "dust theory". Neither the time dimension or the log are shared with the simulating universe, and yet they are still valid for the observers within the universe. If the sequence of the log states is entirely deterministic based on the initial state, then you don't even need to actually write down the entire log for it to "exist". This is Greg Egan's Permutation City.

worstspotgain 2y ago
Can we reduce this to an estimate of survivorship bias? If there is only one universe, then our survival is clearly explained: we're in the only reality there is. If all possible universes exist, then we really lucked out in ending up in this one (well, depending on who wins the election I guess.) In the middle are the permutations selected through the filter of other realities, when they chose which universes to simulate. We lucked out but not as much, because uninteresting universes never made it out of the entropic soup. It would have to be a conditional estimate of course, because our sentience biases our contemplation.

oersted 2y ago

Quick appreciation for the Douglas Adams reference :)

buginprod 2y ago

Randall has you covered: https://xkcd.com/505/ https://xkcd.com/505/

nonameiguess 2y ago

This kind of thought experiment seems like it breaks down due to the uncertainty principle. We can't exactly specify the full state of every particle in the universe. The universe might also be infinite and you can't enumerate an infinite set even without uncertainty, though you can write a generating function or recurrence relation for it, which seems to be Wolfram's point. But why bother with this kind of detail? What's the difference between what you're imagining here and a normal reel of film? It can be played back, but even if it isn't, it records the state of events that happened, including observers that once existed and no longer do, experiencing events that once happened but no longer do. It's possible for a record to describe a canonical sequence even if the record itself doesn't change. Somebody outside of the record can view it out of order, speed it up, slow it down, pause it, reverse it. A film reel doesn't share the time dimension of its own universe in that way. I'm struggling to come up with what this implies and why.

worstspotgain 2y ago
To your first point, if it's a simulated universe, the simulators can just choose to make it finite, and come up with their preferred particle behavior rules. As observers, we perceive time as passing, but is there anything special in this perception? Looked at another way, everything could be frozen in a 4D log book and we couldn't tell the difference, or could we? In this interpretation, Napoleon is as alive (in 1820) as we are (in 2024.) A film reel is a similar concept, except it's just a 3D projection rather than a complete detailed 4D account.
- nonameiguess 2y ago
  I get the questions of eternalism, the reality of the past and future, why privilege the present (or at least my present), and all that. I just don't understand why the fact that you can record events in a medium that doesn't experience the time that it records has any implications for how we should think about this. Whether or not you want to say "Napoleon exists" or "Napoleon existed" seems to be a matter of linguistic convention and the more common latter would reflect speakers privileging their own time. If you want to look at it another way, Napoleon exists, but entirely in my past light cone, and I exist entirely in his future light cone. I can't send him any kind of information, but he can send information to me. Is there anything special in this perception? To who? To observers at the absolute end of all time, my future is just as written in stone as Napoleon's. To observers I can receive information from, my future is unknown. To any particular observer, there are regions of spacetime in which you have no past. There are regions in which you have no future. There is a region in which you have both a past and a future. Is there anything "special" in perceiving the sequence of events within the third region as passing rather than existing forever as a log? Not really. You're just describing a different variety of the Copernican principle or relativity as far as I can tell. But so what? None of us are the center of the univers. None of us exist in a special inertial frame describing absolute spacetime. These facts, however, have consequences in terms of how to measure and compute stuff. They change the kind of testable predictions you make given certain conditions. What computational or predictive consequences arise from observing that the entire world curve of the universe exists at once from a perspective outside of the universe? Going back to the I can't send information to Napoleon thing, if observers outside of our universe are keeping a log, none of us nor anything else in our universe can receive information from them, so what difference does it make? It's an interesting shower thought but kind of also a big so what?

jiggawatts 2y ago

A fun variant of this is that the log can be taken at variable intervals and as long as it is sufficiently detailed, it can still capture all salient details. Similarly a simulation run at some "tick rate" can also be run at 2x the rate while taking 1/2 the step per tick. Within the universe nobody would notice, as long as the steps were fine enough to begin with. I think it was in Diaspora (or Permutation City?) that Greg Egan proposed that any tick rate would be unnoticable to that simulated beings, including "none". In other words, the movie Top Gun will continue to exist as-is, no matter how many copies are made of it, including none. Encoded as a digital file it is just a number, a pure timeless concept, it doesn't have to be written down to exist. It always existed on the number line, even before Tom Cruise was born. In fact, every encoding of Top Gun exists on the number line, in every compression format, in every resolution, even a future 16K resolution that was never filmed and has no display devices made for it yet. Its encoding as a 400GB long number is there, already, and will always be there. In other words, and simulation, an log of events, any experience already exists in mathematics, in every encoding... somewhere on the number line. This includes the entire physical universe. This isn't hypothetical, it's necessarily true! Anything that can be represented by a finite amount of information must be on the number line. Even if you assume the Universe lasts forever, you can break its history up into a sequence of states, each of which is finite. Then the series will exists on the number line as a set of points heading off to infinity.