Essay Abstract

Notions like meaning, signal, intentionality, are difficult to relate to a physical word. I study a purely physical definition of "meaningful information", from which these notions can be derived. It is inspired by a model recently illustrated by Kolchinsky and Wolpert, and improves on Dretske classic work on the relation between knowledge and information. I discuss what makes a physical process into a "signal".

Author Bio

Carlo Rovelli is a theoretical physicists working at the University of Aix-Marseille in France. His main interest is in quantum gravity.

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Fred Dretske is also cited in "Information and Impossibilities" by Jon Barwise.

Another term of interest might be "self." For example in the equation of a non-wellfounded set: "self=(thinking, self)." Are you saying there are items on your list which do not depend on the existence of a "self"-- that something other than "self" would be the first step?

Dear Master Rovelli,

You write:

"As long as an organism is alive, S(xn) remains far lower than its thermal-equilibrium value Smax. This capacity of keeping itself outside of thermal equilibrium, utilising free energy, is a crucial aspects of systems that are alive. Living organisms have generally a rather sharp distinc- tion between their state of being alive or dead, and we can represent it as a threshold Sthr in their entropy."

I simply had to stop reading at this point and interrupt you to ask a question.

First I need to give the context before meaning can be understood.

Experiments have confirmed the Born rule.

Within experimental limits, the mathematical pattern in the data is explained by the Born rule.

The Born rule says that the same number can be output from two independent algorithms.

(Bohm and Hiley had previously said "from two independent concepts.")

Confirming the Born rule is the same, mathematically, as confirming through an experiment that there is an algorithm in the data.

It has the signature of a learning algorithm.

What is it learning?

The laws of physics.

The context for the two algorithms is a game. One algorithm is playing against the other.

The correlation to laboratory experiments is that first you starve a rat almost to starvation.

Then the rat can be studied by making it play a game where the bait is food, and it will die if it doesn't play the gane.

The name of the game for the starving rat is then to figure out which door will yield the food when the game begins, and the door from the rat's living chamber is opened and it can enter the feeding chamber, in which there are many closed doors, each down its own channel in the maze.

For what seems like years to the rat, it has been trained to eat here. Every door smells like food, but you never know behind which door the food will be. Go down the wrong tunnel (each by the way made of transparent plastic) and when all the doors open, there will be no food at this door in the tunnel.

But since everything is transparent plastic, the rat can see all the open doors in the feeding chamber, and easily sees where the food was actually hidden. A light and buzzer go off at the missed food door, just to make sure. Then just before the rat can run to that door where the food is, it slams shut before the rat can get to the food. The rat has long ago learned not to even try.

There are two of the kinds of emotional forces of regret, anger, fear and maybe even self loathing that the rat gets into for each door. (In a previous contest I used Shannon like formulas to model regret.)

First there is all the regret of having chosen it, when the food appeared somewhere else. Opposite to this "entropic" force, is the regret of having NOT chosen it, on having chosen another door but seen the food occurred here.

When these two entropic forces balance, "probability learning" is said to have occurred.

Now back to the algorithms seen in experiments on the Born rule.

It's like the particle needs to refuel or die. It has a need to exist.

How does this need of the starving rat or particle in this situation correlate to the numbers you are writing about?

"As long as an organism is alive, S(xn) remains far lower than its thermal-equilibrium value Smax. This capacity of keeping itself outside of thermal equilibrium, utilising free energy, is a crucial aspects of systems that are alive. Living organisms have generally a rather sharp distinc- tion between their state of being alive or dead, and we can represent it as a threshold Sthr in their entropy."

In terms of your essay, what would these algorithms learning?

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Dear Professor Rovelli,

thank you for an intriguing and original contribution to this debate. Your basic strategy strikes me as distantly related to the one championed by Terrence Deacon: while you focus on the notion of correlation, he frames things in terms of constraints, which are, to him, 'absences' that nevertheless may be causally efficacious. Of course, both notions are, in some sense, just opposite images of one another: a (multipartite) system possessing constraints on which possible states may be realized is just a system exhibiting nontrivial correlations.

Your approach, however, adds considerable conceptual clarity, together with a precise mathematical formulation---while Deacon on the other hand proposes a more refined theory of how the higher-level concepts of meaning emerge from the basic 'thermodynamic' level of systems possessing certain correlations. Perhaps the two approaches might, in some sense, compliment one another.

However, I have a couple of questions I'd like to pose to you, if I may. First of all, I'm not sure I understand how your 'meaningful information' actually acquires meaning, e.g. for the bacterium. I can see how this information is salient in furthering the goal of homeostasis, and thus, how this information---or rather, the correlation between internal and external variables---is advantageous in guaranteeing the bacterium's flourishing. But does this suffice to fashion meaning for this information?

It seems to me that, ultimately, all the bacterium has access to is its own internal variable; based upon its value---say, L or R---it carries out certain actions---i.e. chemotaxis. Now, if the bacterium had, in some sense, access to the further information that its internal variable is correlated to the direction in which a food source is present---i.e. to the knowledge that the only possible states of the system are 'L, food left' and 'R, food right'---then I could see how the value of the bacterium's internal variable constitutes knowledge about the external situation, i.e. the position of the food. But of course, if the bacterium had such knowledge, it would already have to have some fully-functional intentional system (as the fact that 'the only possible states of the system are...' would have to be represented to it in some way)---hence, postulating this knowledge would be circular.

But then, how does the value of the internal variable, to the bacterium, come to be about the position of the food (or perhaps some more simple description of the outside world)? It's clear how it is about that to us, as intentional beings---because we can represent the additional knowledge regarding the constraints of the system. Thus, the 'aboutness' in this case is derived from our intentional faculties. But I don't see how this meaning comes about sans such faculties.

Furthermore, the 'meaningful information' you define hinges on the goal of an organism, imparted to it by the itself goal-less, random dynamics of evolution, to survive. This is a clever move, since it gets rid of the need for any a-priori goal directed behavior: organisms didn't originate with the goal of survival, it's just that only those organisms that behaved as if they had this goal are the only ones that are still around, thanks to the inexorable logic of natural selection.

But human beings can have goals that go beyond survival, and may find information furthering those goals to be meaningful (or at least, apparently so). As an extreme, take a suicidal person: the information that, for instance, a certain quantity of a substance will be fatal if ingested will certainly be meaningful to them, but quite clearly isn't relevant to survival either directly or indirectly. So, it seems to me that there is meaningful information whose meaning does not emerge from the overall 'pseudo-goal' of survival, but rather, from individual goals that do not necessarily align with (and indeed, may run contrary to) the evolutionary dictate. But if that's the case, then there is some goal-directedness that's independent of the meaningful information you define.

Thank you, again, for your essay---as you can see, I found it quite thought-provoking!

    I'm not quite sure why the above comment doesn't show my name; I must've gotten logged out somehow. But anyway, anonymous above is me.

    Dear Professor Rovelli.

    As I have thoughtfully pointed out in my brilliant essay, SCORE ONE FOR SIMPLICITY, the real Universe consists only of one unified visible infinite surface occurring in one infinite dimension, that am always illuminated by infinite non-surface light. There is no gap in any sensible person's "understanding of the world" providing he or she avoids abstract complexity and practices simplicity.

    Joe Fisher, Realist

    "We do not need something external to the workings of nature to account for the appearance of function and purpose." The preceding seems to me to be an important idea. "A signal is a physical event that conveys meaning." It seem to me that the preceding is a satisfactory definition for Einsteinian special and general relativity but not for the Copenhagen interpretation. I think that the definition should be: A signal is a physical event that conveys meaning or might convey meaning in a physical experiment long after the event. I say that that my 3 most important ideas are:

    (1) Milgrom is the Kepler of contemporary cosmology.

    (2) The Koide formula is essential for understanding the foundations of physics.

    (3) Lestone's heuristic string theory is essential for understanding the foundations of physics.

    I would appreciate any feedback concerning the 3 preceding ideas.

      Dear Brown,

      Natural reality is not composed of complex abstract ideas. One real Universe must have only one reality. As I have thoughtfully pointed out in my brilliant essay, SCORE ONE FOR SIMPLICITY, the real Universe consists only of one unified visible infinite surface occurring in one infinite dimension, that am always illuminated by infinite non-surface light. Reality am not a conundrum.

      Joe Fisher, Realist

      Carlo Rovelli,

      What you say is all very well, but you and other physicists like Kolchinsky and Wolpert have made a mistake in your most basic assumptions. Physics likes to claim that fundamental-level reality is mindless, but on the other hand physicists assumes that the universe somehow "knows itself": the universe in some sense "knows" the law-of-nature regularities, the universe in some sense "knows" the parameter numeric values that are the unpredictable physical outcomes of quantum randomness.

      Physics contains a hidden and unacknowledged assumption: that the universe has information about itself; that the universe already knows the same aspects of reality that we humans represent with law-of-nature equations and parameter value numbers.

      But what "knows" the most primitive levels of reality? The universe is seemingly not a single entity, but a collection of interacting entities: particles, atoms, molecules, cells and other living things. These entities are the only candidates that could know, that could have information about (i.e. subjectively experience) reality.

      Then you get to the question of whether there are 2 aspects of reality (physical reality and experience of physical reality, and a relationship between the 2 aspects) or only one aspect of reality (subjective experience of reality).

        This is interesting. I will reread your paper in a couple of days. I seems though you are arguing for a sort of selection mechanism for quantum states. Maybe this is a way of getting a form of "pink noise" from quantum fluctuations, by selecting certain fluctuations, to promote information into the future.

        LC

          Dear Ms. Ford,

          Natural reality does not have abstract levels.

          Simple natural reality has nothing to do with any abstract complex musings such as the ones you effortlessly indulge in. As I have thoughtfully pointed out in my brilliant essay, SCORE ONE FOR SIMPLICITY, the real Universe consists only of one unified visible infinite surface occurring in one infinite dimension, that am always illuminated by infinite non-surface light. Reality am not as complicated as theories of reality are.

          Joe Fisher, Realist

          Carlo -

          There are several things here that I find very good, e.g. your explanations of emergence and of signaling. It's a particularly important idea that physics is "modal" - about structures of possibility, not just structures of given fact. This needs further development from a philosophical point of view, since we still tend to think of possibilities as facts that just haven't happened yet. Your Relational QM paper took a different path by describing facts as answers, which can only exist where the physical context poses a specific question.

          I think it's great to focus on the issue of how information becomes physically meaningful, and your argument makes good sense. But by taking meaning as dependent on biological evolution, I think you skip over something important. There certainly is a level of meaning that depends on the survival and replication of organisms - just as there are many further levels of meaning that only come into play in the human world. But the most basic levels of meaning are entirely physical - for example, it's meaningful that a body weighs 1kg rather than 2kg. It makes a crucial difference to the world that positive charges move in exactly opposite ways to negative charges, etc. etc.

          I'll argue - in my essay yet to be submitted - that all the many kinds of significant differences in physics have meaning because they're all measurable, in terms of each other. Of course, there's no clear understanding of what that means, in quantum physics. I recall your position on this - from the RQM paper - that the only reasonable solution is to treat any correlation between two systems as a measurement. That won't really do though, since entangled systems are correlated whether or not a measurement is made. I think it's better to say that something is measured where there exists an interactive context that defines and communicates a specific result - Bohr's "entire measurement situation." A specific answer only appears insofar as there's an adequately-posed question.

          The problem is that though we know very well what it takes to construct an adequate measurement-context, it's hard to define such a context theoretically. That's because there are so many different ways of measuring different physical parameters, and they're all quite complicated, and every way of measuring one thing depends on measurements of other kinds of things. However, all of this is true of biological reproduction as well. There are many different life-forms that replicate very differently; no reproductive process is in any respect simple; and all these different species depend in various ways on the survival and reproduction of other species.

          Happily, Darwin showed us how to understand the hugely complex system of life. In physics, though, the classical mode of explanation still prevails - as in your statement, "Nature appears to be formed by a relative simple ensemble of elementary ingredients obeying relatively elementary laws." This is of course true down to a certain level, but there's hardly any empirical support for it in the Standard Model plus gravity. Which aspect of all these interaction-laws do we consider "relatively elementary"? I think we need to work toward a mode of explanation that, like Darwin's, doesn't rely on reduction to ultimately simple components.

          The analogy between physical measurement and biological self-replication seems remote, since they accomplish such different things. But I hope to show in my essay that they're two very different instances of the same kind of dynamic structure, through which meaningful information is able to evolve. And also, that a third instance of this structure is at the root of human communication.

          Nonetheless your essay is as usual very clear and insightful, and on the track of what seem to me the most fundamental issues.

          Thanks - Conrad

            Dear Prof. Rovelli,

            Very interesting - perhaps a bit too technical however for the purposes here (in other words, it's well above what would be deemed Scientific American material.)

            Sometimes as scientists we write for colleagues, and sometimes to draw in a more 'lay' audience - as you did in your recent 'Reality Is Not What It Seems'

            very well done anyway

            Kind regards

            H Chris

            Dear Mr.Rovelli,

            I have liked a lot your papper and how you interpret these informations.One of my favorite,you are going to win a prize :)The technical method is relevant,I didn't know the works of Wolpert and others.I know the Shannon works a little.Thanks for sharing in all case,I learn in the same time these methods.

            Good luck in this contest.

            Regards

              Hi Lawrence, happy to see you again on FQXi ,but where were you :) ?

              The idea comes from nonstandard analysis, in the works of Naval College Mathematics courseware instructor, Robert A. Herrmann, the great genius of a nonstandard world he calls "theNonStandardNatural" .model of the Universe, versus "theStandardNaturalNumber" Universe, where everybody else lives.

              He writes about Relativity. I interpret him here.

              There is a Universe of Time where everything in the Univese is an Object.

              And then, there is the Universe where everything in the Universe is a Process.

              Objects within the Universe of Objects speak a very different language from the language.spoken in the Universe of Processes.

              Mysteriously, Einstein had correctly described an "infomorphism" between these two Universes.

              And that, was his equation between "local Minkowski ProperTime," and "Coordinate Time."

              But since it was an infomorphism, it was only half of the story.

              Because an "infomorphism" has to connect to itself by two back and forth channels-- or functions-- or arrows. (Take your pick.)

              The other half of the Infomorphism is the "Stream" that's the Universe of Time, where everything in that Universe is a "Stream."

              And that's where I come from.

              Seems there should be a lot more than just one equation involved!

                The author proposes that correlation between objects is ground for meaningful physical information. Meaningful information nurtures aims and intentions experienced by the living. If we can describe mathematically meaningful physical information, we then have found at the very least a remote mathematical description to aims and intentions, as I understand. The author further proposes a variation of the formula for entropy for said mathematical formulation. I should add that the author has asserted several key aspects of a physical definition of the living. In my sense, this thesis should be well received although the argument is somewhat weak. Several flaws in style and grammar should be noted.

                Dear Carlo Rovelli,

                you made a nice effort to describe the first tender emergence of some 'meaning' on our planet, as you imagine it to have possibly happened, so i like to leave some comments about what came to my mind by reading your essay.

                In your essay abstract you wrote „I discuss what makes a physical process into a "signal"." You also wrote in this abstract "I study a purely physical definition of "meaningful information", from which these notions can be derived."

                By discussing what makes a physical process into a 'signal', you have tacitly correlated the term 'process' with a mindless physical process, whereas your term 'signal' should signal! to the reader that somehow there is an observer of that signal (bacterium) and knows how to interpret it.

                So you have correlated 'process' with mindless matter and 'signal' with a kind of observer. You wrote that your definition of 'meaningful information' is a purely physical one. The question for me is how a mindless physical process can, via selection and reproduction, become an observer. Surely, if this would be possible, it would happen in small evolutionary steps, but i see no such steps existent other than an essay author correlating the term 'process' with the term 'signal'. But this would be only 'relative information', because there is no observer existent for the 'signal' to recognize it. I think the meaning of your 'meaningful information' can only come into play, because the reader projects her/his experience with hunger and death into the situation of a bacterium, *as if the reader himself would be that bacterium*.

                As long as we do not define this bacterium to be conscious to a certain extent, i think one cannot speak of some food in front of a bacterium as a signal. This does not exclude that we assign a certain meaning to this signal, but by doing so, we *do* it, and surely not the bacterium. It is true, that whenever the bacterium finds its food, its chances to exist longer are increased. But we conclude this from our point of view. A mindless physical process, driven by chance, cannot meaningfully have any point of view. There is no meaning of death and hunger in a purely physical definition of that process.

                Your attempt gives the impression that whatever 'survives' a certain selection process, must necessarily be able to discriminate between an advantage and a disadvantage. Surely, it is imaginable that the bacterium could have some rudimentary sense of advantage and disadvantage. But this would presuppose also some rudimentary state of inner awareness of what is going on out there. Unfortunately, for explaining how this rudimentary state of inner consciousness could at all come about in a purely physical universe, one had to begin with the whole inquiry from where one started it - because the emergence of this inner awareness would be left unexplained (unless one simply claims that it emerges and period). This is - in my opinion - part of the hard problem of consciousness. I really appreciate that scientists are concerned with these questions, but as you rightfully note at the end of your essay, the results should be received with cautiousness.

                  In the Kyoto lecture of 1922, Einstein said:

                  "There is an inseparable relation between time and signal velocity."

                  Wikipedia states that: "The signal velocity is the speed at which a wave carries INFORMATION.

                  It describes how quickly..."

                  "...a MESSAGE can be communicated between two separated parties."

                  An "informationalist"-- as I understand it-- might read the above paragraphs in the following way:

                  In nonstandard analysis, Robinson taught us about languages and models.

                  Looks like there is a model in these paragraphs.

                  But it would be the first step in informationalism to think-- instead-- about languages and SITUATIONS.

                  As in: "situation theory" from Jon Barwise's book "The Situation in Logic."

                  (Robinson and Barwise were friends long ago at Yale.)

                  Back to "the situation":

                  "What type is it?"

                  If you ever read The Informationalist's Handbook, that is the very next question.

                  Well-- to support all this talk about "information," "message," "sender," "receiver," and so on, there clearly must be an "information channel" in this situation. It must be -that- type of situation. Otherwise, how would the information be transmitted, how would the message be carried?

                  The term "information channel" comes from Barwise's second to last book, the one with Jerry Seligman: "Information Flow: The Logic of Distributed Systems."

                  On the cover, there are diagrams of information channels between pieces of office equipment.

                  Diagramming tools, of course, were in-scope for that workshop with Barwise--

                  "'Business Applications of Situation Theory:

                  Algebra, Relativity, Diagrams, and Situations' at Work"

                  You can imagine the T-shirts.

                  I've still got one around here somewhere. (A colleague had paid a friend to do the artwork. It's Alice in the Red Queen's race.)

                  To understand TIME in his own mind, Albert Einstein went outside himself to imagine clocks, situated on machine bases if you will.

                  It's always been opaque to me as to how this imaginary apparatus of clocks and rigid rods puts into operation anything like the most profound idea that Einstein had ever had about time:

                  "The only reason for time is so that everything doesn't happen at once."

                  If we only had just one more model of time!

                  Then we could compare it against Einstein's, above, and see which model comes closer to this deep, intuitive insight.

                  Here's how I found such a model--

                  There were millions of dollars at stake in a monster manufacturing line. Nobody could say for sure whether or not it would work. It did look great in blueprint form. And in those days, it actually was a blueprint!

                  So they did an RFP for a computer simulation from a local conveyor company. But I told them I could get it done in half the time.

                  So I wrote the purchase order for Smalltalk80, which had just come on the market no more than a couple of months previous.

                  Then I went to OOPSLA in San Diego, got another Smalltalk80 with every class for every queuing mathematics, semaphores, scaleable parallel computing system, everything you needed to write a multi-threaded, parallel simulation.

                  This became a diagramming tool I then used to draw the Petri net of the manufacturing system. Each Petri net transition would generate it's own code. I could just point and click, to add code to a transition here, a transition there. There were hundreds and hundreds of transitions. But really, it was just a small net.

                  Here's the problem I ran into:

                  Say I had a conveyor feeding parts into a press. In the real world, they can back up till everything stops. But in the very first stages, what my Petri nets would do is just keep feeding every part into the press as soon as it came along-- destroying all my simulated work!

                  So to every transition in the simulation, I added a "feedback loop." It was an INFORMATION CHANNEL.

                  The feedback loop held a place for a game coin.

                  When it finished its work, each transition in the net would place a coin in it's own feedback loop slot. It was the SIGNAL "ready for more work."

                  Only when that SIGNAL existed, could a part then move into the press.

                  (Moving a part into the press somehow "removes" the coin.)

                  Those were the rules.

                  I had to give the press some simulated TIME so it could do its work.

                  And to give it that TIME, I had to:

                  "Keep everything from happening at once."

                  *****

                  "The only reason for time is so that everything doesn't happen at once."

                  Now, we have another model for comparison.

                  So here are two models for saying some things about TIME:

                  1. Clocks on bases of rods sending signals

                  2. State transitions with feedback loops to "self," running an algorithm in a simulation that "keeps everything from happening at once." I.e, a STREAM.

                  It looks like #1 is better for a model to say things about "coordinate time."

                  While #2 is better for saying things about "proper time."

                  As I understand it, so far in GR, proper time is DEFINED based on coordinate time. Here, both would be "independent" processes.

                  That would pretty much be like Bohm and Hiley's statement about the Born rule-- that the two sides of the equation are two "independent concepts."

                  Here then, the two independent concepts are "coordinate time" and "proper time."

                  To an informationalist, the defining equation for proper time based on coordinate time now looks like an "infomorphism," like the Born infomorphism.

                  But an infomorphism can exist only if an information channel exists.

                  There needs to be an information channel so the defining equation of proper time from coordinate time can become a transmission of information.

                  Please see previous post-- objects (using language about coordinate time) and processes (using language about proper time) both swim in a stream. The stream affords the information channel.