It would be nice if this was a problem with decidablity, but often it is a problem with indeterminacy that is way stronger than classic chaos.

The speed of causality or I information is the limit that is the speed of light.

Even in the case of entanglement, useful information is not ftl, If I write true on one piece of paper and false on another and randomly seed them to Sue and Bob, Sue instantly knows what Bob has as soon as she opens hers. While we teach QM similar to how it was discovered, there are less mystical interpretations that are still valid. Viewing wave function collapse as updating priors vs observer effects works but is pretty boring.

While wormholes are a prediction of the theory, we don't know if the map matches the territory yet. But it is a reason to look for them. But if we do find them it is likely that no useful information will survive the transit through them.

Kerr's rebuke of Hawkings assumption that black hole singularities are anything more than a guess from a very narrow interpretation of probably unrealistic, non rotating, non charged black holes is probably a useful read.

The map simply isn't the territory, but that doesn't mean we shouldn't see how good that map is or look for a better one.

You can’t really prove things in physics, but to my knowledge we don’t have observations that contradict locality.

I've been thinking about this comment a bit. What do you mean that it's far from being proven? Wouldn't this mean there is some evidence for something faster than c?

They will never reach us because the rate of expansion is accelerating.

Well, it doesn’t evolve. You just render it as evolving to perceive yourself / itself. The only way to have the state of being of observation and perception is to not be everything which gives rise to directionality.

One of my toy theories-of-everything is that we live in a branch of something akin to a Mandelbrot set. A trivial rule is all that is needed to produce infinite complexity. Sure, zoomed out a fractal can look simple, and even zoomed in (a lot!) it still looks trivially repeating, but if you zoom in enough eventually the complexity becomes high enough to represent something like the universe and the life within it. You can even squint at it and just like how the Mandelbrot set appears to fork repeatedly, parallel universes (like in MWI) could be forking off by the dint of following one path or another through this fractal space.

This makes a good argument that the block universe can't exist: https://aeon.co/essays/who-really-won-when-bergson-and-einst...

(search "block")

But wouldn’t each brain still be frozen in a moment of time? Don’t you still need something that moves the “play head of the universe” from one moment to the next?

Boltzmann brains are extremely ephemeral.

An analogy is that of stirring a vat of alphabet soup and noticing that there is a fair number of single-letter words popping into view ("A", "I"), a smaller number of two-letter words, an even smaller number of three-letter words ... a very very small chance of a twenty-letter word ... and a vanishingly small chance of the 189819-letter monster <https://en.wiktionary.org/wiki/Appendix:Protologisms/Long_wo...> popping into view. The stirring doesn't stop just because a multiletter word appears, so multiletter words are quickly broken up and even valid single-letter words get hidden behind the "B"s and "Q"s and other letters in the soup.

Boltzmann brains will fluctuate out of existence on the order of a small multiple of the light-crossing time of the brain-matter that fluctuated into existence. As the brains are human, they won't even have a chance to react. Although their false memories are encoded however true memories exist in our own brains, they'll have no time to have a reminiscence or notice their lack of sensory organs. (Which is probably good, since they would quickly suffer and die from lack of pressure and oxygen).

A Boltzmann-brain with a full encoding of a life worth of false memories (from never-existing sensory input) is a much larger number of letters. Also, in a cold universe, the stirring is slower, and the letters sparser. Boltzmann brains are tremendously unlikely except in a verrrrrrrrry big volume of spacetime. But with a sufficiently big volume of spacetime, or one with an energetic false vacuum, one should expect a lot of Boltzmann brains. This view puts some limits on our own cosmos's vacuum, since we don't see lots of Boltzmann brains (or even much less complicated but RADAR-detectable and/or eclipsing strucures) fluctuating into brief existence in our solar system.

Boltzmann brains are low-entropy. A persisting Boltzmann brain (fluctuating into existence and staying in existence for a long time) is much lower entropy still. This poses problems for hypotheses that the entire early universe fluctuated into existence and then evolved into the structures we see now. Here there are human brains attached to sensory apparatus, whose memories correlate fairly well with their history of input (and recordings by ancestors, and fossil records, and so on): a system with much much lower entropy than Boltzmann brains, so what suppresses relatively high-entropy structures (including Boltzmann brains) from dominating (by count) our neighbourhood?

Also, if the universe supports large low-entropy fluctuations, galaxies that briefly (~ hundred thousand years) fluctuated in and out of existence should be much more common than galaxies with a history consistent with billions of years of galactic evolution, and you'd expect random variations in morphology, chemistry, and so forth; that's not what we see.

This is a bit annoying, as it would be handy to point to Boltzmannian fluctuation theory as the source of the tremendously low entropy in the very early universe, i.e., it could have arisen spontaneously in a less precisely ordered space. Oh well.

> why would ... a universe appear to evolve from a low entropy past following a small set of laws

Thermodynamics.

The issue is: where did the low entropy past come from? Once you have that, evolving into a higher entropy structure-filled present is not too hard -- that's essentially what we have with the standard cosmology from about the electroweak epoch onwards.

So in summary:

> sequences of Boltzman brains who all subjectively experience time as sequential

whatever these might be, they aren't Boltzmann brains, since the latter don't subjectively experience anything as objectively they fluctuate out of existence in something like a nanosecond.

Very briefly, the short existence is driven by interacting fields and the need to keep entropy (relatively) high: if your starting point just before the appearance of the brain is a region that is high quality vacuum, you have to come up with protons, calcium nuclei, ... and all that requires very careful aim to have one split-second "movie frame" of brain. You need much better "aim" which really drives down the entropy (which corresponds a much larger fluctuation) to go from vacuum to a Boltzmann brain that doesn't disintegrate starting in the very next frame thanks to overshoots of momentum.

The higher the entropy of the Boltzmann brain, the clearer the stat mech argument. (If one gets stuck thinking about human brains, C. elegans apparently develop memories and store them in their nerve ring. Why isn't the outer space of our solar system full of those Boltzmann-C.-elegans brains fluctuating in and out of existence with each possessing false memories of sensory stimuli? Smaller fluctuations, so there should be many more of those than human Boltzmann brains).

> a block universe

I first encountered this theory and the related "eternalism" philosophy via Alan Moore [1] (Watchmen, V for Vendetta, The Ballad of Halo Jones, Swamp Thing, Batman: The Killing Joke, From Hell, etc.). Watchmen and its non-Moore-affiliated sequel have a lot of riffs on time and determinism.

Q: Jerusalem deals with the idea of eternalism: everything that has happened is happening right now and forever. Could you explain your views on this?

A: My conception of an eternity that was immediate and present in every instant – a view which I have since learned is known as ‘Eternalism’ – was once more derived from many sources, but a working definition of the idea should most probably begin with Albert Einstein. Einstein stated that we exist in a universe that has at least four spatial dimensions, three of which are the height, depth and breadth of things as we ordinarily perceive them, and the fourth of which, while also a spatial dimension, is perceived by a human observer as the passage of time. The fact that this fourth dimension cannot be meaningfully disentangled from the other three is what leads Einstein to refer to our continuum as ‘spacetime’.

This leads logically to the notion of what is called a ‘block universe’, an immense hyper-dimensional solid in which every moment that has ever existed or will ever exist, from the beginning to the end of our universe, is coterminous; a vast snow-globe of being in which nothing moves and nothing changes, forever. Sentient life such as ourselves, embedded in the amber of spacetime, would have to be construed by such a worldview as massively convoluted filaments of perhaps seventy or eighty years in length, winding through this glassy and motionless enormity with a few molecules of slippery and wet genetic material at one end and a handful or so of cremated ashes at the other. It is only the bright bead of our consciousness moving inexorably along the thread of our existence, helplessly from past to future, that provides the mirage of movement and change and transience.

A good analogy would be the strip of film comprising an old fashioned movie-reel: the strip of film itself is an unchanging and motionless medium, with its opening scenes and its finale present in the same physical object. Only when the beam of a projector – or in this analogy the light of human consciousness – is passed across the strip of film do we see Charlie Chaplin do his funny walk, and save the girl, and foil the villain. Only then do we perceive events, and continuity, and narrative, and character, and meaning, and morality. And when the film is concluded, of course, it can be watched again.

Similarly, I suspect that when our individual four-dimensional threads of existence eventually reach their far end with our physical demise, there is nowhere for our travelling bead of consciousness to go save back to the beginning, with the same thoughts, words and deeds recurring and reiterated endlessly, always seeming like the first time this has happened except, possibly, for those brief, haunting spells of déjà vu.

Of course, another good analogy, perhaps more pertinent to Jerusalem itself, would be that of a novel. While it’s being read there is the sense of passing time and characters at many stages of their lives, yet when the book is closed it is a solid block in which events that may be centuries apart in terms of narrative are pressed together with just millimetres separating them, distances no greater than the thickness of a page. As to why I decided to unpack this scientific vision of eternity in a deprived slum neighbourhood, it occurred to me that through this reading of human existence, every place, no matter how mean, is transformed to the eternal, heavenly city. Hence the title.

1: https://alanmooreworld.blogspot.com/2019/11/moore-on-jerusal...

How can you imagine any world without experience (observation?) thus any observer is dependent on position thus time simply because it is the partial history that allows the state itself to exist.

And your second point is essentially the metaphysical argument for god and early spirituality. Hebrew mystiscm for example describes god pouring itself into lower forms of being to experience itself

Said a human.

If it’s not time-like, then it’s everything, thus it can’t have experiences thus god. God splits (monad becomes many) to experience being (shards in multiplicity of the one through division: oooh spooky golden mystery).

Yeah, god is everything, which can’t have experience, as it’s experiencing everything at once - thus the monad splits itself, allowing perception as a fraction of the whole which is experienced as time and direction.

Science is philosophy, albeit just a branch of it- specifically the part concerned with learning how the universe works physically.

Other branches of philosophy study other things, and are good at understanding those things they are about. Moreover, philosophy has progressed and branched out quite a bit since those philosophers you mentioned. I spend a lot of time reading philosophy for fun, and have found many of the ideas practically useful in regular life- but am not a fan of any of the philosophers you mentioned, and find their work mostly useless or outdated.

Funnily enough, the scholastics thought of philosophy as the handmaid of theology. Ultimately, it's in the name (love-of-wisdom). You can learn wisdom from science, but that body of wisdom eventually becomes a philosophy. And the older philosophers definitely saw something, even if they are not completely correct.

Why are you so confident that Philosophy isn't the superclass to "science"? How could you hope to start on any science without philosophy, much less arrive at a definition for the term? I could maybe see mathematics without philosophy, as I mentioned above, but physical science/physics/"science" is inherently subjective. That doesn't mean truth doesn't exist, of course -- but I'd have to get into philosophy to explain why I think all of that ;). The best defense for philosophy by far is that you can't criticize it without engaging in it, and "it all seems obvious to me, just use common sense"-style citations are much less convincing than ones to long famous books.

More provacatively: have you engaged with it? I know that's a big ask, but it's also a bit unfair IMO to write off a field without taking the time to understand it. For example, Aristotle founded multiple scientific fields, including the big two -- Physics and Biology -- and established a theory of mind that still has immense sway in the west to this day. Kant was a reknowned scientist before he started into philosophy (even having a good claim to "first to show the existence of galaxies"), and the quote above is from A Critique of Pure Reason (https://www.gutenberg.org/files/4280/4280-h/4280-h.htm#chap1...) where he establishes cognitive science:

  From all that has been said, there results the idea of a particular science, which may be called the Critique of Pure Reason.... Such a science must not be called a doctrine, but only a critique of pure reason; and its use, in regard to speculation, would be only negative, not to enlarge the bounds of, but to purify, our reason, and to shield it against error—which alone is no little gain.

Without the academy, we'd have no Francis Bacon, no Newton or Liebniz, no Einstein or Bohr, and definitely no Popper, Kuhn, Carnap, Wittgenstein, Chomsky, or any of the other amazing modern thinkers on how to improve our scientific endeavors. This one's less verifiable but I imagine it hits home the most: I don't even think we'd have Turing without Boole, Russell, and Whitehead to draw from.

...sorry, clearly I'm a bit sensitive ;) It's frustrating being valued for your puzzle solving abilities (aka SWE) much more highly than your engagement with science, as I'm sure you can relate to or imagine!

The mother of someone who was a friend in the 90s used to always pepper her speech with attributions for almost everything she was saying (in any "serious" conversation). "I think it was Popper who said ..." "Schenk developed this idea that ...")

It was * so * annoying to listen to.

Real scientists tend to try to be careful about attribution and especially don't just blatantly regurgitate the last thing they read and pass it off as their own. That is highly frowned upon in polite academic society.

My body disagrees.

Great way to let someone down who asks you out.

There are no branches in the Ruliad in which you and I end up together. I have foreseen it.

You vastly misunderestimate infinity if you don’t recognize that anything feasible will happen.

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

The word "simulation" is it self a simulation. So is the word "is".

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.

We don’t know for a fact that QM contains irreducible indeterminism. If many worlds is true, then QM is ultimately deterministic. Same if hidden variables is true. A large class of local hidden variable theories have been ruled out by Bell’s theorem, but non-local hidden variable theories survive it (such as the Bohm interpretation and the transactional interpretation), as do local hidden variable theories which deny the Bell theorem’s assumptions about the nature of measurement, such as superdeterminist local hidden variable theories.

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?

Reminds me of https://xkcd.com/505/

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?

The gatekeeping and manipulation going on in formal scientific publishing is notorious, but that is not the issue here.

The fundamental algorithm of advancing physical science has always been: a set of "principles" or proto-concepts, a set of matching mathematical tools (that dont even need to be very rigorous), using these tools to explain a slice of reality (experimental outcomes) and, finally, predicting unknown behaviors that can be sought, can be confirmed (and celebrated).

Sometimes even just a purely equivalent mathematical representation is fine, as it may give handles for calculations and thinking.

But whatever the program with digi-physics is, it doesnt follow these age-old patterns that establish validity and usefulness intrinsically and not because some gatekeepers say so.

The primary utility seems to be to enhance the prestige and toolkit of computational physics, which is fine, but totally not justifying the universality claims.

Surely that's logic/maths where accepting the axioms means that the conclusion has to be accepted? Philosophy tends to be far less rigorous and can have very dubious steps so that there's often arguments where you don't accept the conclusion despite accepting the axioms.

e.g. https://en.wikipedia.org/wiki/G%C3%B6del%27s_ontological_pro...

It’s part of their life cycle https://www.smbc-comics.com/comic/2012-03-21

What is specifically crank about his theory? From outsiders perspective having theories that require a bunch of extra dimensions just to make the math work sound no less cranky.

Is it a question about nature of time or about our perception of time though?

Because the universe is evolving from a low entropy state to a high one.

You can't exactly predict the future unless you have all the information, even theoretically.

> I think that's partly because the simple experiments, like cellular automata, he used to come up with this principle actually explore the 'space of simple rules', not the 'space of ordered sets of states of systems'.

I think it’s the opposite actually. He chose to study these recursive systems because they seem to describe reality, and then when he found more evidence that they do a good job describing reality, he kept studying… so on and so forth. Basically a sort of hermeneutic circle type deal.

You do a much more thorough job of describing it. I should’ve mentioned the recursive part earlier. I just kinda assume we all already know we’re talking about recursion and time steps and that’s not a useful assumption

Your comment makes me think about statistical mechanics and microstates. That is to say ... in a complex system with properties that are a function of microstates, whether the internal structure of the microstates that correspond to a given property matter can depend on your point of view or interest in the system.

Heat, for example, is a statistical property of a system, and a given temperature can correspond to a vast number of possible microstates of the system. For some purposes, you care precisely which microstate the system is in; for others, you do not, and the temperature property is entirely adequate to describe the system.

Rules may describe the microstate, but may be (depending on your POV) be irrelevant to the property.

Using Wolfram's model of the world, there may indeed be a cellular automata following rules that underlies the property, but there may be no reason to care about it in a given instance; instead you're interested in the "evolution of states" (i.e. values of the property).

Some complexity scientists are quite taken with this idea of not needing to care about the lower levels of a system when consider higher level behavior. In their view (and rightly so, IMO [0]) you don't always need to consider the rules that drive (say) physics when considering (say) psychology.

[0] except that I think that Hofstadter's "heterarchy" idea is likely to be even more accurate - interesting systems are the ones in which there are complex feedback systems between different levels of the system.

So apparently the inside of the Black Hole event horizon is just "Forty Two".

Yes that's pretty much it

But is the theory that such work can continue forever?