[HN Gopher] Communication costs are 35-fold computational costs ...
___________________________________________________________________
Communication costs are 35-fold computational costs in the human
brain (2021)
Author : ofou
Score : 139 points
Date : 2022-05-15 08:14 UTC (14 hours ago)
(HTM) web link (www.pnas.org)
(TXT) w3m dump (www.pnas.org)
| apienx wrote:
| The PNAS editors involved in this clickbait-y title need some
| introspection. You can be rigorous and generalist.
| [deleted]
| SemanticStrengh wrote:
| Also cognition only consume 0.2 watts
| mjburgess wrote:
| I have friends who are non-science PhDs and absolutely believe
| anything published in a science journal must be absolutely sound.
|
| Before I started reading I thought, "alas, its going to be
| pseudo-science again right?".... and as far as I can see, yes,
| basically it is.
|
| 1. Logical bits are not thermodynamic bits, so a thermodynamic
| analysis of the brain can only be compared to a thermodynamic
| analysis of CPUs (if one wishes to compare at all)
|
| 2. Every phrase which begins "suppose, assume, conjecture"
| introduces fatal assuptions into the whole project, extremely few
| are defensible. The idea that a single neurone is "computing"
| whilst its "communication" with others is non-computational in a
| _logical_ sense is clearly false. One can make a thermodynmic
| distinction between energy "of the neurone" and "of thier
| 'communication'" this distinction has no relevance to a
| computational-logical model of the brain as a computational
| system.
|
| 3. The frequent reference to thermodynamic limits of
| "computation" (in a logical sense) as a baseline for comparison
| with (abitary) parts of the brain, is meaningless. The
| thermodynamic efficiency of the brain is _interesting_ only
| insofar as any possible logical model of the brain seems to imply
| vastly more "computational resources". And vastly more
| thermodynamic resources than CPUs have. Physical limits on
| theoretical computation pertain, if they are even themsevles
| coherent (which is disputed), to the absolute minimal possible
| "piece" of reality, not even, i'd say, to any _measurable_
| phenomenon. As soon as a system has to engage in measurement, i
| 'd say it would be millions+ times less "efficient" than
| 'physical limit's would suggest.
|
| One "trick" to see through the pseudoscience of computational
| neurobiology is simply to apply its methods to actual CPUs and
| computers. With the above assumptions, this paper would conclude
| that only one operation in a transistor is "computing" anything,
| the energy required to do that is "the energy of computation"...
| and the rest of the energy used across CPU(-RAM-etc.) was "merely
| communication".
|
| As-if all algorithms were _logically_ specified as a purely
| parallel series of switch-flips. No, algorithms (in a
| computation-logic) sense have nothing to do with switch flips.
| And their implementation on digital computers requires _many_ ,
| serial and parallel and "thermodynamic communication" between
| them _to perform the computation in question_.
| kingkawn wrote:
| Well said.
|
| I'd only add that neurons are part of an exponentially higher
| dimensional calculation process than binary, taking input from
| a huge number of chemicals, proteins, electrical signals,
| insulation variability, and who knows what other undiscovered
| dynamics that are at play. There is no 1:1 comparison between
| computers and the brain anymore than there was between
| aqueducts and the brain.
| gnramires wrote:
| I think you're missing reading non-hard sciences. In science
| every analysis that clear states its assumptions and models is
| valid. You don't have to derive everything from axioms and
| physical laws. You can make assumptions and simplifying models
| and operate within that, as long as you clearly state your
| assumptions that may or may not hold -- that's fine. This is
| common in engineering papers.
|
| > Logical bits are not thermodynamic bits
|
| They are lower bounded by thermodynamic bits? (in the sense of
| energy for instance) The thermodynamic bits are exactly that:
| information (although it seems information in thermodynamic
| theory is still not perfectly well understood).
| mjburgess wrote:
| They arent lower-bounded by thermo bits --- because one can
| specify algorithms which require no thermodynamic work to
| implement. Logical bits and thermo bits are related by
| contingent facts of _implementation_. One has first to
| specify an algorithm (defined in terms of a computational
| model), _then_ it 's an open question as to what-and-how
| it'll be implemented.
|
| It's also not at all clear that the physics terms "entropy,
| information, bits, etc." have anything to do with their
| computational "equivalents". Only by fairly strained thought
| experiments do we get _alleged_ connections. Even these
| thought experiments only provide _extremely limited_
| translation of these terms between domains.
|
| "Information" in a "logical" sense is a radically different
| think than in a "thermodynamic sense"... for example, the
| former has an obvious observer-independent definition, the
| latter does not.
|
| The whole game of trying to bridge these notions _without_
| specifying implementation relations (etc.) is largely the new
| form of that transhumanism-craze: the respectable ideological
| space of delusional techno-utopian hopes.
| mordechai9000 wrote:
| > one can specify algorithms which require no thermodynamic
| work to implement
|
| Can you give an example? To my limited understanding,
| performing work without expending energy sounds like
| perpetual motion.
| mjburgess wrote:
| Sure, this is the trap of thinking of computer science as
| either being about computers (machines) or about science.
| As _mostly_ a kind of pure discrete mathematics, we need
| to be careful.
|
| Consider an algorithm which says:
| while(true) state *= +1, state *= -1, state *= +1, ...
|
| Now, identify the +1 state as _the earth when in one-half
| of an orbit_ , and the -1 as _the earth in the other
| half_. And therefore the position of the earth as _the
| logical bit_ ( "the state") and its movement as _the
| change to the logical bit_.
|
| This is "perpetual motion", but the technical name in
| physics for this is _inertial motion_ , and its common.
| Motion itself doesn't require work, _using_ that motion
| for work, requires work.
|
| See also
| https://en.wikipedia.org/wiki/Reversible_computing
| svnt wrote:
| Can you provide a non-theoretical example where an extant
| inertial body actually does no work? I believe this is
| impossible. You've just moved the assumptions to where
| they frame your perspective better than that other thing
| which competes with your perspective.
| mjburgess wrote:
| Energy is always conserved. Just define the computer to
| be the system in which energy is conserved, and there you
| go.
|
| A "computer" is a formal pure-mathematics notion, it is
| just a certain sort of "discrete mathematical model". One
| can define a computational model of any physical system,
| and hence, find computers in which energy is conserved.
| hnaccount_rng wrote:
| I was on a workshop once where the topic was entropy and
| somehow we got into a discussion regarding Maxwell's
| Damon... This strongly reminds me of that discussion.
|
| The problem for the Damon is, that it needs to change the
| state of the trap according to the state of the incoming
| particle. And if you just hand wave "such a decision
| making thing exists", then you have your contradiction.
| But we tried, for several days, to come up with _any_
| implementation (including fantasy materials) that could
| conceivably exist _and_ produce that effect. And for each
| and every attempt to build one, we came up _immediately_
| with diffusive parts, where energy _must_ be lost. We
| concluded, that while non of us would feel confident to
| _rule out_ a possible existence of Maxwell's Damon, we
| wouldn't _at all_ be surprised if it could be ruled out.
|
| So while you are entirely correct, with enough hand-
| waviness, you can build reversible computations. But I
| have yet to see an argument, where a _potential_
| implementation of one is argued to the end.
| mjburgess wrote:
| It's sufficient for my purposes just to show that "bit"
| in a logical model and "bit" under some idealised
| thermodynamic thought experiment are _radically different
| notions_.
|
| Reality, i am sure, has many systems which are _settable_
| and _measurable_ and _changeable_ at some minimum
| energy... and which can interface with _devices of
| interest_. For any given problem, the limit case energy
| requirement is _defined by the needs of the algorithm_.
| If we require setting a highly complex input state, and
| if we require interactions with certain devices, then we
| 've immediately ruled out a great deal.
|
| These systems would provide you with a certain kind of
| "limit-case correspondence" between "logical bits" and
| "ideal physical bits" --- but we dont know what this
| system is. You dont get it from just playing around with
| units, nor these kinds of thought experiments. You need
| to know what algorithm you're talking about, and what
| it's requirements are.
|
| If the algorithm is understood just to be "the whole of
| reality" and if we suppose that it is fundamentally just
| aggregates of discrete states being flipped (to me,
| highly unlikely).... then the energy requirements are
| Everything... which sum, i imagine (via energy
| conservation), to zero.
| User23 wrote:
| An enjoyable and approachable text with more detail on
| reversible computing and energy expenditure from the
| perspective of physics is the Feynman Lectures on
| Computation[1].
|
| [1] https://www.goodreads.com/book/show/17274.Feynman_Lec
| tures_O...
| sudosysgen wrote:
| If you really want to be pedantic, even infinite inertial
| motion isn't possible, because a true vacuum is
| impossible, and there is thus necessarily drag somewhere.
|
| Also, I've said that before, but we already know that
| brains operate under an irreversible computation model.
| User23 wrote:
| > Also, I've said that before, but we already know that
| brains operate under an irreversible computation model.
|
| We don't know that brains operate under any kind of
| computational model at all. It's often postulated, but
| it's not proved. Every attempt I've seen at a proof
| reduces to begging the question.
|
| Edit: To be clear I'm not saying a computational model of
| the brain can't be a useful tool. Newtonian physics works
| quite well quite often even though reality isn't
| Newtonian.
| sudosysgen wrote:
| To be clear, I'm not saying that everything the brain
| does can be modelled by a known computation model. All
| I'm saying is that the interesting part of what the brain
| does is computation, in that it takes in data, operates
| on it, and returns data. It does this in an irreversible
| manner because you cannot determine the input from the
| output (nor a significant part of it).
|
| If there is any model of how the brain works it will be a
| computational model. Perhaps a new one, and perhaps a
| radically different one, but it's still going to find the
| definition of a computational model.
| User23 wrote:
| Ultimately, the open question here is this: are
| uncomputable functions just a mathematical fancy, or do
| there really exist processes that can only be fully
| correctly described by uncomputable functions?
|
| Personally I lean towards latter view. I'm the first to
| admit that I have no proof. It's just my belief, because
| I find the metaphysical evidence compelling. I don't
| object to investigating the former possibility, but I
| also don't care for it just being baldly asserted.
|
| If the answer is affirmative, that means that science
| will probably never be solved and we'll just have to
| content ourselves with incremental improvements in our
| understanding. That's observably been the case up until
| now. Granted even if all processes are in fact described
| entirely by computable functions we might still never
| discover what they are.
|
| I hope it's clear how all that relates to the concrete
| problem of understanding human cognition and the brain.
|
| I'm nowhere near smart enough to even begin to conceive
| of a mathematical framework for taming noncomputable
| functions in a pragmatic way, but I earnestly hope some
| genius comes along who is, supposing that noncomputable
| functions are needed to completely describe our reality.
| sudosysgen wrote:
| That's pretty much useless, though. We know for a fact that
| the brain uses irreversible computational processes and
| that essentially all the input information is erased. So
| the lower bound is indeed valid. There is indeed a
| necessary connection between thermodynamic bits and logical
| bits. Indeed, since we know that we can assume irreversible
| computation, we know that the computation isn't dominated
| by those zero-work algorithms.
|
| And indeed, if you minimally look at the neuronal model of
| computation, you can obviously see that computation is
| going to be irreversible (though reversible calculation is
| possible in theory).
|
| Now, you're right that there is a lot of wiggle-room for
| implementation, but the lower-bound is indeed robust. So
| there is clearly value to the argument.
| mjburgess wrote:
| Any correspondence between formal properties of the
| algorithm, namely, the logical model of the system _and_
| its physical properties *requires* (1) the algorithm; and
| (2) the implementation model.
|
| Speaking about "computational processes" and
| "reversibility" _at all_ , absent these, is meaningless.
|
| What exactly, of the brain is the "computational process"
| ? What exactly is "irreversable" ? This is really just
| pseduo-science, though it may not seem it.
|
| We have no idea whatsoever what a logical model of
| anything to do with animal intelligence _is_ , and hence,
| absolutely no idea what properties of animals (local to
| the brain or otherwise) are relevant to them implementing
| this logical model. To say any process of the brain is
| "computational" is either to say something useless
| (namely in the sense in which every process is
| "presumably, somehow computational, given a logical
| model") -- or, to say something pseudoscientific.
|
| I would agree that animals, in modifying their
| environments by conceptualising them and developing
| skillful techniques to regulate themselves in response to
| them (ie., largely: intelligence), are highly
| thermodynamically irreversible systems.
|
| This isnt a useful observation, given in pseudo-csci
| terminology, absent a correspondence between this
| physical facts and the _presumed_ logical model of the
| computation going on.
|
| If the whole of reality is an algorithm, it's one (via
| energy conservation) which requires zero energy to run.
| Ie., "logical bit" and "thermal bit" are radically
| different notions. They are connected _contingently_ when
| one has an algorithm to-hand, and knows how it will be
| implemented.
|
| There's nothing to be said about the logical bits of
| animal intelligence, ie., nothing to be said
| _computationally_ , because we have no idea what they
| are.
| sudosysgen wrote:
| No, there is no pseudo-science there, except when one
| takes the statements to mean more than they actually
| mean.
|
| >Any correspondence between formal properties of the
| algorithm, namely, the logical model of the system and
| its physical properties _requires_ (1) the algorithm; and
| (2) the implementation model.
|
| >Speaking about "computational processes" and
| "reversibility" at all, absent these, is meaningless.
|
| This is simply not true. We start from the assumption (as
| does all theoretical CS) that computational models are
| equivalent in capability.
|
| We observe that the brain has inputs and outputs. We
| observe that the outputs are at least partially
| determined by the inputs.
|
| From this, we can conclude rigorously that the brain does
| computation, and there is thus a computational process
| going on in the brain.
|
| >What exactly, of the brain is the "computational
| process" ?
|
| The correlation between inputs and outputs that follows a
| process in which information is transformed. This is
| readily observable.
|
| >What exactly is "irreversable" ?
|
| It is impossible to reconstruct the input from the
| output, therefore the computation is said to be
| irreversible, and is thus subject to various
| thermodynamic limits.
|
| Therefore, we can rigorously conclude that the brain
| performs irreversible computation.
|
| >We have no idea whatsoever what a logical model of
| anything to do with animal intelligence is, and hence,
| absolutely no idea what properties of animals (local to
| the brain or otherwise) are relevant to them implementing
| this logical model. To say any process of the brain is
| "computational" is either to say something useless
| (namely in the sense in which every process is
| "presumably, somehow computational, given a logical
| model") -- or, to say something pseudoscientific.
|
| Now you're just taking what I said far above and beyond
| its actual meaning, and taking that interpretation to be
| pseudo-scientific. I said nothing about intelligence, all
| I'm saying is that there are computational processes
| going on inside the brain, and that those are
| irreversible. We don't need to know what algorithm is
| going on, nor do we need to know the precise model of
| computation, to be able to draw conclusions.
|
| One of the conclusions we can draw is that the brain
| executes irreversible computation, and that the general
| algorithms implementing those computations _must not be
| zero-work_.
|
| That is done without needing to know the details you seem
| to argue are necessary to draw such a conclusion.
|
| We can also conclude more from this. We can, for example,
| place lower and upper bounds on the information being
| processed by various elements.
|
| Now, someone could take this methodology and abuse it,
| or, as the article does, use it in conjunction with
| supplementary assumptions and go beyond absolute rigour.
|
| >If the whole of reality is an algorithm, it's one (via
| energy conservation) which requires zero energy to run.
| Ie., "logical bit" and "thermal bit" are radically
| different notions. They are connected contingently when
| one has an algorithm to-hand, and knows how it will be
| implemented.
|
| Now you're going way beyond what we can rigorously
| ascertain. If you consider the whole of reality to be a
| computer, then what are the inputs, and what are the
| outputs? Perhaps you consider the process of time to be
| an algorithm with the past as an input, in which case it
| is an algorithm that does require energy to run because
| it's performing irreversible computation, unless there is
| hidden state somewhere.
| xpe wrote:
| Thank you both for writing in considerable detail to seek
| clarification.
|
| I can tell some aspects are still lost in translation,
| though. It isn't easy.
| mjburgess wrote:
| "computation" is only equivalent when it's calculative,
| ie., when the algorithm in question is _merely_ computing
| some number.
|
| The reason the LCD screen displays some output isn't
| because the electrical switches have some _numerical
| state_ , its because they have some _electrical state_.
|
| The sense in which "computer" describes any system is
| trivial, for there to be any empirical content to
| computational language, we need an empirical model of the
| relevant algorithms the computer is performing.
|
| My kettle is also a computer: water is its state, boiling
| is the "computational process", and its change of state
| is the "number being computed".
|
| But it is only a kettle because that "calculation" which
| computes a number is a magnitude which _is implemented
| by_ the kinetic state of the water.
|
| The sense in which "computers are equivalent" is
| *empirically empty*. There is no scientific content to
| this; it is merely a statement of pure mathematics. To
| use this language, of pure discrete mathematics, as-if it
| is informative about empirical systems *is pseudo-
| science*.
|
| One may as well say the brain is a geometrical system
| which is extended in Euclidean space, and we know
| topologically, that all such systems are geometrically
| equivalent.
|
| The world science studies (unlike that of pure
| mathematics), is extended in space and time, and has
| properties (eg., charge, mass, etc.). The number
| "34029348309384398" is only a frame of a video game when
| it names (charge, mass, extention, duration...) in a
| highly particular manner.
|
| Unless you have an algorithm in mind, and a model which
| says how its _numerical content_ corresponds to _physical
| properties_ , you arent saying anything empirical at all.
| sudosysgen wrote:
| >"computation" is only equivalent when it's calculative,
| ie., when the algorithm in question is merely computing
| some number.
|
| Whoever said that computation has to be with numbers?
| Here we are seeing the brain as calculative, because the
| output of the brain is some function of it's input, is it
| not? Surely we can agree that this is an important,
| crucial, and interesting function of the brain, that is
| worthwhile to study? I'm not saying that this is
| necessarily all that the brain does, but it's an
| interesting and unresolved dimension of what the brain
| does, perhaps even the most interesting.
|
| >The reason the LCD screen displays some output isn't
| because the electrical switches have some numerical
| state, its because they have some electrical state.
|
| Sure, I don't see how that's an issue. Why does
| computation have to be on numerical states? It can be on
| any kind of state at all, even continuous states. Be it
| water pressure, base pairs in DNA, luminosity, anything
| at all that can represent data. In fact, some of the
| earliest algorithms were operating on lines and circles,
| which are neither numerical nor even discrete.
|
| >My kettle is also a computer: water is its state,
| boiling is the "computational process", and its change of
| state is the "number being computed".
|
| Sure, you could see it that way. But computation isn't
| the only thing your kettle is doing - and it's not the
| interesting part about it either.
|
| > The sense in which "computers are equivalent" is
| _empirically empty_. There is no scientific content to
| this; it is merely a statement of pure mathematics. To
| use this language, of pure discrete mathematics, as-if it
| is informative about empirical systems _is pseudo-
| science_.
|
| It's far from purely mathematical, nor pseudo-scientific.
| Sure, you could define almost anything to do some
| computation, but that doesn't mean the computation it is
| doing is worthwhile, or an interesting dimension of its
| operation. Certainly, however, the computational
| dimension of the human brain - that is, how it
| manipulates data - is the most interesting part of it.
| It's clearly informative - in this case we can conclude
| that the brain does irreversible computation, and thus
| establish various bounds on how it operates.
|
| > One may as well say the brain is a geometrical system
| which is extended in Euclidean space, and we know
| topologically, that all such systems are geometrically
| equivalent.
|
| Sure, we can say that. How is this helpful in this
| context? Understanding the brain as doing computation is
| certainly helpful, and perhaps understanding it as
| topologically equivalent to other objects is too, but I
| can't really see how.
|
| >Unless you have an algorithm in mind, and a model which
| says how its numerical content corresponds to physical
| properties, you arent saying anything empirical at all.
|
| Again, why does an algorithm even require a numerical
| content? All an algorithm needs is data, and we clearly
| have data going in and out, which constrains the physical
| system that is processing that data.
| mjburgess wrote:
| Adding an additional comment here, as I'm thinking to myself
| about how I'd clarify the issue further.
|
| Suppose we write a program in `C` which requires 32 bit array,
| sets an input state, operates on the array, and produces an
| output state. This program is the _logical_ model, here
| requiring say 32bits and 10 operations /bit average. So we have
| 320 logical changes to the array (which btw, wont be purely
| parallel or serial).
|
| Suppose the most efficient CPU we have requires E_thermo energy
| for this whole process (setting the 32bit input, operating,
| reading the output).
|
| Now, using somewhat disputed ideas about physical limits,
| E_thermo say implies we've used 320,000 'bits'
| thermodynamically, ie., somehow the CPU has produced an
| equivalent of 320,000 "energetic changes".
|
| So the CPU has an efficiency, in some suspicious sense, of
| 100,000 thermo-bits / logical-bit. For each _single on-average_
| change to the array we see in the `C program`, we theoretically
| measure an equivalent heat of 100,000 changes.
|
| Now, how efficient is the brain at computation? Well since we
| have no logical model of the computation its performing,
| there's absolutely no way of answering that question.
|
| So why do people say it's efficient? Well because any
| apparently equivalent algorithm we come up with (in, eg., `C`)
| to do even basic things that the brain does, requires vast
| amounts more energy. Eg., processing images on a GPU requires,
| say 300 W, and our whole brain uses (a claimed) 20 W.
|
| I think the resolution to this problem is that the
| brain(-environment-body) system implements computation in a
| radically different manner than anything like a CPU, GPU, etc.
| I suspect that computation happens at every scale: molecular,
| sub-cellular, cellular, neuronal, inter-neuronal, nervous-
| system, body, body-environment, etc. And across the whole body,
| and using energy in the environment to maintain state.
|
| However, I find the use of the term "computer" and
| "computational" mostly just productive of pseudoscience. It is
| a basically meaningless term that only produces confusion. The
| only useful area where it helps is when handling logical models
| of algorithms -- models largely absent from the whole of
| empirical and theoretical science.
| rad88 wrote:
| What did you mean by "computation" then? Honestly curious,
| because it seems you could also say a digital computer does
| it at all scales: semiconductor junctions, capacitors,
| clocks, their multipliers, transistors, up through logic
| gates, blocks, buses, ..., and all the way out to the fans,
| power supply, etc?
| mjburgess wrote:
| I mean that if "intelligence (etc.)" in the relevant sense
| can be described by an algorithm, its implementation will
| not just depend on properties neurones have _as neurones_.
| It 'll depend on properties at various scales.
|
| This isnt quite true for digital computers, in the sense
| that the only property which implements the algorithm is
| the electrical switching state... that this state depends
| on, eg., silicon isnt quite the same as silicon-properties
| the ones "doing the work".
|
| This is part of the trouble talking about "computation" at
| all, which is a nearly empty term in my view.
|
| Consider an example. A "baking a cake" algorithm can be
| implemented by a person or a factory, if specified
| correctly. In one case, the organic properties of a person
| appear "essential to the implementation", but they arent.
| But there are some algorithms which do require organic
| properties (eg., if we consider the behaviour of a cell
| wall an algorithm) to implement.
|
| The question is _in what sense_ are the implementation
| properties "doing the computational work". Any electrical
| system which provides switching states is "doing the work
| in the same way", ie., there are certain "macro-properties"
| which _do the work_ , regardless of their micro-property
| dependencies.
|
| I think in the case of intelligence (the brain-body, etc.)
| the properties "doing the computational work" arent the
| macro-properties of neuronal interaction. They're
| properties at various scales (subcelluar protein
| behaviours; celluar interation; neuronal communication;
| bodily organization; environmental driving; etc.).
|
| In particular, i think it's the self-adapting self-
| organizing properties of certain organic systems that allow
| them to implement "the intelligence algorithm" -- this
| algorithm, if it can ever be specified, I do not think will
| be implemented only by macroscopic neurone firing -- i'd
| say that'll be a very minor part of its implementation. I
| think most of it will come from self-organization
| properties from the subcell to the body.
| dav_Oz wrote:
| Your very valid points are - in my reading - addressed in this
| paper, albeit in a milder and more forgiving form, in the
| _Results_ section under _A Baseline for Maximally Efficient
| Computation. A simplistic model relates physics to
| neuroscience._
|
| Especially: _That is, physics looks at each computational
| element only as a solitary individual, performing but a single
| operation. There is no consideration that each neuron
| participates in a large network or even that a logical gate
| must communicate its inference in a digital computer in a
| timely manner. Unlike idealized physics, Nature cannot afford
| to ignore the energy requirements arising from communication
| and time constraints that are fundamental network
| considerations (43) and fundamental to survival itself
| (especially time) (18, 19)._
|
| I wouldn't call it outright pseudo-science as the authors are
| trying to impose some limited working framework with very
| technical meanings of "communication" and "computation" in this
| context. I too, find this "physics"/"cs" excursion very basic
| and questionable which kind of points to the purpose of that
| paper: demonstrating an exercise. And as a general symptom the
| difficulty to overcome the shallow waters of interdisciplinary
| fields/approaches.
|
| [From my own experience in talking with biologists only after
| awhile I begin to appreciate the deep complexities of
| biological/biochemical systems, only to - after some time has
| passed - forget those subtleties again. I'm so used to simplify
| from my physics background that it is actually quite hard to
| recognize important distinctions in different (more complex)
| fields which can lead to vastly different mathematical models.]
| mjburgess wrote:
| If this were one paper in isolation, I'd call it an honest
| attempt at good science gone-wrong by a lack of consultation
| with theoretical computer scientists and specialists in
| thermodynamics.
|
| However, I think _this is just *the entire field*_ -- which
| is then different. I think a whole field is pseudoscience
| when it systematically engages in the same games. I think
| likewise of much fMRI work,... all the way to basically the
| whole of nutritional science, etc.
|
| If the premises of your project can be pretty quickly
| falsified by relevant domain experts, and you build a whole
| field out of it, you slip into my category of
| "pseudoscience".
|
| This paper explicitly tries to prescribe to engineers (!!!)
| where their "focus" should be, having absolutely no warrant
| to do so. A trivial application of the same analysis to CPUs
| would provide the relevant baseline comparison the paper
| should have made. With this analysis, the key results of the
| paper would be exposed as useless.
|
| I have little sympathy for all this now: it's a research hype
| cycle craze to apply random bits of computer science to
| random bits of science in the most hairbrained manner.
| [deleted]
| 867-5309 wrote:
| >it's a research hype cycle craze
|
| perhaps you should address this in a counter paper rather
| than an HN comment. researchers have to justify grant money
| and regularly twist the facts to accomplish this, that's
| just how the system operates. let the dregs drag and the
| Einsteins elevate. a large percentage of "research" quite
| rightly never sees the light of day. groundbreaking and
| globally impacting discoveries and inventions are only a
| few in a century
| titzer wrote:
| > With the above assumptions, this paper would conclude that
| only one operation in a transistor is "computing" anything
|
| Why? A transistor is just an arbitrary boundary. You could as
| well draw a box around any combinatorial circuit and just call
| it a "computational element". It has inputs and outputs and a
| switching energy for each unit of computation it does.
|
| This is just the process of breaking computation up into
| abstractions--"boxes".
|
| Clearly we must do this, otherwise we'd have to reason about
| individual electrons.
| svnt wrote:
| Electrons themselves being just easily-measured boundaries
| around littler bits we'd be forced to acknowledge that our
| entire modeled reality is constructed.
| ineedasername wrote:
| I dunt ned thet metch too comkate, mebe 2x. Mkay, 3x.
| max_entropy wrote:
| How can computation be separated from communication?
| tombh wrote:
| I think Noam Chomsky even believes that human's language
| ability was selected for to aid computation not communication.
| Therefore in humans: communication IS computation.
| SemanticStrengh wrote:
| Asking the real questions.
|
| Axons are connected to the neuron and exchange a lot of
| chemicals between them. For example, the mitochondria in axons
| go back and fort to the neuron IIRC. It's not very googlable
| but neurons have a memory of how likely they are to trigger an
| action potential, based on past stimuluses/timings. No one
| knows where this memory is encoded. And is there one action
| potential per axon? If so then it would be more logical for
| this memory (and computation which leads to mutation to the
| memory) to be stored in the axon (if).
| noduerme wrote:
| This _feels_ like it wad generated by GPT-3. Am I going nuts? I
| just came to HN after falling into a whirlpool of "Best Coffee
| Makers for 2022" SEO spam sites (waste of a Sunday morning), and
| noting how each AI-written "review" followed the same
| introductory pattern of chitchat. And then I come here and find a
| paper that sounds like it's by the same AI author.
|
| >> Darwinian evolution tends to produce energy-efficient
| outcomes. On the other hand, energy limits computation, be it
| neural and probabilistic or digital and logical. Taking a
| particular energy-efficient viewpoint,
|
| Someone tell me that's not GPT.
|
| Compare with this from a coffeemaker fake review site:
|
| >> The more features something has, the more you can make use of
| it, such is the principle rule of products and services alike.
| This rule is why companies try to compete with each other on
| their best products.
|
| >> Hence, the brand Imusa is no exception to this, as they make
| an electric mocha maker that is loaded with features. To unpack
| all of the features, we must start with the build quality and
| work all the way down to the specifics.
|
| [edited to add comparison]
| echelon wrote:
| Your direct quote sounds like any scientific paper.
| svnt wrote:
| It's the loose use of "on the other hand" when the two
| constraints are not clearly first presented as being in
| opposition.
|
| I am frankly not sure that either of those are GPT-generated
| --- perhaps they can be read instead as illustrative of word-
| count driven human egotism and inconsistent writing.
| anonymousDan wrote:
| It reminds me a bit of the field of wireless sensor networks from
| back in the day, where the main challenge was that wireless
| communication was typically much more energy intensive than local
| computation requirements and so there was an incentive to perform
| additional computation locally that might reduce communication
| (e.g. to filter or aggregate data).
| anotherhue wrote:
| intra-neuronal communication, not 'talking to people' (tiring as
| that may be).
| calculated wrote:
| Thank you for this specification as the OP hasn't put it in the
| title. Before reading your comment I thought the article is
| about human interaction.
| devonallie wrote:
| Maybe it's because I've been spending too much time thinking
| about packets, but I thought it was "digital" communication.
| xwdv wrote:
| It's crazy how I was willing to believe that this is what the
| article was talking about without even opening it. Authors
| should be more specific, a lot of misinformation could be
| spread through misleading titles.
| nanofortnight wrote:
| "Communication in the human cortex" seems pretty clear. The
| abstract is there for an extended summary if one doesn't wish
| to read the whole article.
|
| One cannot possibly understand the nuances of something
| without reading it; I do not feel knowledge gained through
| reading titles of articles is usable knowledge. Perhaps one
| should consider changing the habits of the reader rather than
| the author?
| xwdv wrote:
| A lot of that nuance would be quickly forgotten, but the
| info from a good title could last a long time.
| layer8 wrote:
| I believe you mean _inter_ -neural communication? But, in
| consequence, by "computation" they must mean intra-neural
| computation? Because otherwise (i.e. for inter-neural
| computation) the "communication" would be an integral part of
| the computation. Or do they really mean that most of the energy
| cost of neural computation must be attributed to inter-neural
| communication?
| rileyphone wrote:
| This is in line with [0], which argues that modularity in small-
| world networks produced by evolutionary processes is largely a
| result of connection costs. It's unfortunate that science here
| has such a limited empirical footing given the importance of the
| knowledge, but that doesn't make it wrong, just circumspect.
|
| 0.
| https://royalsocietypublishing.org/doi/10.1098/rspb.2012.286...
| SemanticStrengh wrote:
| People should review how much this study is coherent of not with
| this one
| https://www.biorxiv.org/content/10.1101/2020.04.23.057927v1....
| photochemsyn wrote:
| Really, this whole field seems like woo. It seems safe to
| conclude that neurons are not taking in sensory data,
| converting that data to numbers, then running little discrete
| algorithms to decide whether the external stimuli can be safely
| ignored or not, using other numbers stored in their internal
| registers to modify that decision. The von Neuman cycle of
| fetch-decode-execute is not a useful model for coordinated
| neuronal activity, and logical bit operations have little
| relevance to biological neuronal activity.
|
| If people want to take a look at more reliable science on this
| area, this is not a bad place to start. In particular look at
| the 141 citations.
|
| _Central command neurons of the sympathetic nervous system:
| basis of the fight-or-flight response (Science 1995)_
|
| https://pubmed.ncbi.nlm.nih.gov/7570024/
|
| This is important and interesting science, and has relevance to
| understanding and treating things like anxiety disorders
| (probably related to hypersensitivity to external stimuli), but
| there's no evidence that any 'computational model' has much
| relevance. These systems really appear to be analog in nature,
| not at all digital.
|
| Also, the lead statement in that paper, i.e. _Darwinian
| evolution tends to produce energy-efficient outcomes_ , may
| sound good but in real cases it seems to vary a lot. While a
| flight-or-fight response is likely under constant positive
| selection (and hence energy-efficient), think about animal
| mating behavior. Are the endless mating rituals, breeding
| displays, etc. at all 'energy efficient'? Large amounts of
| brain energy are devoted to such activities in all species.
| Certainly there are evolutionary arguments for this, but energy
| efficiency is not the main issue.
|
| Perhaps, one could claim that each individual neuron is
| something like a CPU, in that it has state, something like an
| internal memory, but it's a rather vague relationship. Maybe a
| network of biological neurons is something like a network of
| connected CPUs, but it seems doubtful such CPUs rely on
| Arithmetic and Logic Units or bitwise operations.
| colordrops wrote:
| Sounds like AWS.
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