THE
REALITY CLUB George Dyson, Cliff Pickover, Joseph Traub, Jaron Lanier, Stewart Brand, William H. Calvin, Marvin Minsky, Charles Simonyi, Stewart Brand, Kevin Kelly, Lee Smolin, Philip W. Anderson, Marc D. Hauser, Jordan B. Pollack, Nicholas Humphrey (Most
recent — top) If information in DNA — in genes — is digital, while information in culture — in memes — is analog, the answer has to be that life was digital, and will be analog. From: Jordan B. Pollack Date: March 7, 2001 Freeman's material definition eliminates the idea that software could be alive, and places no constraints on the direction of the process. I prefer the lower level thermodynamic definition: a process far from equilibrium which dissipates energy and creates a local reversal of entropy. All the other elements of life-as-we-know it, like information and replication would fall right out, were we were to really understand self-organization. As a computer scientist, whether life is analog or digital seems to me to be the wrong question. It is a similar question as whether a chair must be made out of wood or plastic. "Chairness" is in the organization which enables a platform of a certain height to support a certain weight. Similarly "life" is a measurement of the organization in a system. The yes or no answer to the "is it alive?", is like the yes or no answer to the question to "is it hot?" So it doesnt matter whether a system is made from silicon, carbon, chips, polymers, potentiometers, relays and motors, legos, or tinkertoys or even pure software. What matters is where the biologically complex organization will come from. I think both (analog) complex dynamical systems and (digital) software engineering have been failures at even recognizing the scope of the problem of biological complexity. All the mathematical models of complex systems theory focus on quite low dimensional systems, like cellular automata, and mostly on convergence phenomena or pretty graphics. And AI-type programs like symbolic manipulation systems as well as trained neural networks, always reduce to small bits of organization: business logic plus a relational database — or a polynomial with lots of parameters to set. There seems to be a fundamental limit to organization which is buildable by human teams. In fact, a dirty secret of the software engineering field is that 2 or 3 good programmers can build anything, and tools and fancy methodologies havent changed the equation. Hundreds of other people are necessary just to keep businesses going and to tweak the code to market. Big computer programs are just "suites" of separate 1 million line programs, requiring a human brain in the middle to select and apply different functions usually via a menu system. The amount of organization in a single autonomous biological cell dramatically exceeds the amount of organization of a modern computer program. The real question is how do we get self-organization of systems going to the point they achieve biological complexity, not whether they are digital or analog in nature. From: Marc D. Hauser Date: March 7, 2001 We now know a considerable amount about the biological basis of number representation — surely Stanislas Dehaene will weigh in here! What we have learned from studies of animals, human infants and adults, and patients with brain damage, is that all such creatures have, minimally, an analog magnitude system for computing the number of objects or events. this system, mediated by a mechanism that can either count or time, is approximate, falls under the constraints of Weber-Fechner law, and thus can do small or large numbers approximately. Some of us (e.g., me, Sue Carey, Liz Spelke) believe that this system is joined by another that can do small numbers (< 4) precisely. The emergence, in human history, of a large precise number system was contingent upon the acquisition of language. Thus, no other animal and no child lacking language will acquire a large precise number system, one capable of true digital quantification. However, relevant to the digital-analog issue, it looks like much if not most of the natural world makes decisions in an analog fashion. From: Philip W. Anderson Date: March 7, 2001 I have the impression that the best answer to any question in the form "is X Y or Z?" is almost always "neither!" (As, for instance, was Bohr or Einstein right?") To focus strictly on life as an information process is to miss the point, widely. This is a mistake I myself was guilty of in my two decades old papers on the origin of life, buying too naively into the "RNA world" and the idea that self-replicating information was the essence of life. In his most recent book, "Investigations", Stuart Kauffman defines a living organism as "an agent which can act on its own behalf". Perhaps this is too restrictive, perhaps one should add replication and say "and its descendants' behalf", but the crucial word here is "act". The information-handling capacity — sensing the gradient of nutrient for a motile bacterium, finding the direction from which the sunlight is coming — is merely a facilitation of the basic requirement, which is to go out and find a source of energy and to convert that energy into work. Work here is defined in its thermodynamic sense as energy without entropy, energy which can be used to drive the system as far out of equilibrium as may be necessary to achieve the basic goal of survival and reproduction.
To put this in Freeman's terms, something will
have to maintain, the black cloud or the silicon
chip against, at the very least, the depredations
of other black clouds or silicon chips wanting
the same energy source, and Stu and I would
argue that it would be this maintenance object
which is actually alive. The information which
the cloud contains represents a large departure
from thermal equilibrium and to maintain and
use it, or to replicate it accurately, work
will be necessary, and the schemes described
do not tell me where the work is coming from. From: Lee Smolin Date: March 7, 2001 I am troubled by two assumptions that Freeman and others seem to be making. First that there are only two choices for how information can be coded, digital and analogue. Second, that nature is analogue, apart from some quantum phenomena. Both seem to be false, and this leads to a possible resolution of Freeman's quandary. Consider the problem of classifying the embeddings of arbitrarily complicated graphs in three dimensional space, up to topology. The problem is topological and combinatorial, no continuous variables are involved, but it is not known if there exists an algorithm which can solve it in finite time. It is plausible that the problem is unsolvable. There are other topological and combinatorial problems that are known to be non computable, for example classifying four manifolds or classifying finite groups in general. If the classification problem cannot be solved then the information coded in the embedding of a graph is not digital because there is no algorithm which can in a finite time reduce the topology of an arbitrarily complicated graph to a representation in terms of a finite string of ones and zeros. But no continuous quantities are involved as all that is relevant is the topology of the embedding. Furthermore, even if the problem is solvable in principle, it is likely that the time required to classify a graph will grow extremely fast as the complexity of the graph is increased. Thus, even a moderately complicated graph may be knotted in a way that no digital computer could classify in a physically relevant amount of time. So it is certainly the case that the information contained in such topological problems is not digital for all practical purposes. Is this relevant for nature and for Freeman's query? Most likely yes. One of the basic results of quantum gravity is that at the Planck scale the quantum states of geometry are coded in terms of combinatorics and topology. In fact the quantum states of a large class of quantum theories of gravity are in one to one correspondence with the embedding classes of certain graphs, called spin networks. If there is no finite procedure for classifying the embeddings of graphs in three space up to topology then there will be no digital representation of the information coded in quantum geometry, in spite of the complete absence of continuous variables. Even if the problem is solvable in principle, it is still almost certainly the case that no digital computer built from a subsystem of the universe will be able to classify the possible quantum states of the geometry of the universe in a number of time steps fewer than the age of the universe in Planck units. Two other results of quantum gravity, the Bekenstein bound and the holographic principle, require that only finite dimensional state spaces are required to code the quantum information that can be extracted from any region of the world with a finite area boundary. So it seems likely that continuous variables play no role in nature, but at the same time, this does not mean nature is digital in the ordinary sense. The problem is that these finite dimensional state spaces have bases which are distinguished by solving the problem of classifying embeddings of graphs. So while the holographic principle says that no observer in the universe can access more than a finite amount of information, that information may be stored in a way that cannot be represented digitally by any computer that could be built inside the universe. Now, coming to life, one can wonder whether cells may make use of combinatorially coded information that is not efficiently coded digitally. Possibilities for such codings are not hard to find. For example, the topologist Louis Kauffman has hypothesized that information about turning genes on and off may be partially coded in the knotting of DNA molecules. To support this hypothesis he points to the existence of enzymes which change the topology of the folding of the DNA molecules. The difference between combinatorial and digital coding of information is that when information is coded digitally all the possible states of the memory are equally accessible. When information is coded combinatorially, say in the knotting of some graphs, this is not the case, the time required to store or retrieve information depends very strongly on the state in which the information is coded. But a cell is not a general purpose computer, and there is no need that all possible configurations of the molecules where information is stored be equally accessible. What is required is only access to those states that are relevant for the functioning of the cell, and then only at the time they are needed. (Similarly the protein folding problem does not have to have a solution for arbitrary amino acid sequences, only for the much smaller subset that are relevant biologically.) So I do wonder whether the digital metaphor may be blinding us to ways in which information could be stored in biological systems using the combinatorics and topology of molecules. This seems relevant for Freeman's worry, for if information can be stored in the topology of a system, then the system can be cooled or expanded arbitrarily without degrading the information. At the very least, if the universe has non-trivial topology, on either the large or small scale, there are possibilities for storage of combinatorial information where the discreteness of the states are maintained for arbitrarily low energies. At worst life will be able to survive by coding itself into the quantum geometry of space itself. From: Kevin Kelly Date: March 6, 2001 The discussion so far has made me wonder if my computer is digital. I inspected my iMac to see if I could tell. There's a lot of stuff in there. The monitor part is definitely analog ‹ all those rasters and light waves and pixels. There's a power supply which I know is not digital but analog. There's the CD, which Minsky assures me is a soft analog rock. I see hardware ‹ it is analog, yes? And circuits boards. I have not tried measuring them, but I suspect a lot of the electrical currents running through the printed wires in this device would have analog curves. Eventually we get to the CPUs. How much of what goes on in these little chips actually resembles digital processes? I have no idea, but my suspicions are high at this point. Even if all the activity in the chip was digital (and I doubt it), it's only a small part of the life of this machine. Ah, but it is the most essential part, if not the ONLY essential part one would say. Maybe. Reducing the activity of the entire computer to the abstraction of its CPU as a way to measure its digitalness seems almost tautological; it's like reducing life to its genes. If only a part of my computer is digital, and maybe not as much as I first thought, then is this a perspective, as Jaron suggests, that can change depending on how one looks at it? Is the digital/analog question like particles and waves? It may be that life is "both" not in the sense of being part analog and part digital, but that it is all digital and all analog at the same time. As for what that means to the prospects of life eternal, I guess that means "both." Life will continue forever and will die out, too.
Stranger things have happened. From: Charles Simonyi Date: March 6, 2001 Letters carved in a rock are definitely digital (not binary, but digital). Bison carved in the rock may be called analog, unless it is a part of an alphabet, in which case it would be digital too. (pictures of egyptian deities on an inscription: definitely digital, that is why they were called the "enead", the group of nine (or eleven?) The information carried in digital form (Hamurabi, etc.) from ancient times was incredibly durable. digital rocks. I am not sure if life is analog or digital. Freeman seems to take it for granted that the universe is analog ‹ (with good reasons ; ‹ ). But maybe the issue is: Are real numbers real? (or was this one of the Y2000 questions already?) Certainly quantum energy states are digital in spirit. In a popular column I said that they help gold to remember that it should shine and water that it is supposed to be a liquid. In an alternative analog world all of these interesting properties would be quickly forgotten as the electrons would wind down into the nucleus in a truly analog fashion.
Best wishes to all. From: Stewart Brand Date: March 6, 200l
My point on digital is nonprofound. Just that
reading a CD in 30 years will be a chore, like
reading an 8 inch floppy now. Rocks and paper
stay readily readable ‹ the eyeball platform
is fairly constant over centuries, and alphabets
seem to leave a lineage you can trace back for
understanding old forms. Language is mutable though,
sometimes evanescent. From:
Marvin
Minsky Umm, surely a CD is just a small soft rock. Still, a CD can be made with a good deal of redundancy. A 650 megabyte hand carved rock would consume a square kilometer or so. Besides, it is not really analog. It is digital with a local redundancy of the order of 10**20 in molecular atom placement. By the way, I don't agree with Dyson's assessment of Pour-El et al's theorem. The assumptions are based on the existence of continuous real variables. That amounts to first throwing the baby into the bath, and then appearing to magically take it out. I suspect, instead, that the universe has a finite information density. I also suspect that there's no way to prove either that or the contrary. So, on second thought, forget it. From: William H. Calvin Date: March 6, 2001 I am happy to see life defined not only as info acquisition and storage but the ability to do something with it, to act in the real world. Contemplation without action has been so much the model, at the high end of the scale, that we forget that consciousness really ought to be formulated as readiness for action, generating and improving plans for the next move. I get involved all the time in neurophysiological cautions to Moravec's uploading, and to some extent the same cautions apply to the basics of life, not just higher intellectual functions. Organisms are always in the process of turning into something else, whether aging on the individual level or evolving on the species level. Yet they have to maintain their integrity in much the same way as any other bureaucracy; variations around the fringes are OK but there is a developmental core that has to remain very conservative. So robustness is always a consideration: how well does the organism bounce back when perturbed? As we all know, digital media (including DNA) have the ability to avoid degrading copies and, if mutations occur in a master record, a certain resiliency about fixing it. I don't hear of analog examples of such fidelity and robustness. From:
Stewart
Brand
When you compare digital storage of data (eg.
a CD) with analog storage (eg. letters carved
in rock), analog is proving to be far more durable
over time. Mathematically it's not a profound
difference, but practically it is. From: Jaron Lanier Date: March 6, 2001 It seems to me that there's an epistemological difference between analog and digital systems. A digital system must adhere to an idea of what constitutes a bit, and an on and off state for a bit. This idea, which might be thought of as a "standard" for a given fundamental digital platform, is a way of interpreting digital information content in a fundamentally analog system. A digital system can only be defined or perceived through the use of this kind of extra layer of specification, or what might be called in another context an extra layer of "subjectivity". A digital interpretation's very essence is that it ignores a lot of information in the system; It is made artificially finite and therefore more easy to understand and predict for many purposes. Any digital system can be made to "die" by putting it in extreme conditions where either the bits dissipate or the difference between the on and off states is no longer present in a useful way. Therefore, I think a better question to ask is, "What digital interpretations of living systems might prove to be useful?" There might be multiple useful ways in which the human brain can be thought of as a digital system. Each of these might have a different idea of the material instantiation of a bit and the states of a bit. For the same reasons that there is no perfectly reliable digital computer in the real world, there will be no perfectly applicable mapping of a digital interpretation onto a natural system such as a brain. But we should expect useful digital interpretations (indeed there is already a thriving community of computational neuroscientists), and I hope we will not be burdened by an a priori bias about whether a single mapping or many should be emphasized in the future. The possibility of such a bias is why it's worth pointing out the epistemological issue. (Also note that temporal and phase-sensitive phenomena in natural living systems can be particularly hard to interpret with sufficient resolution digitally — so it might take a while before we have powerful enough computers to usefully map onto some behaviors of analog brains.) From: Joseph Traub Date: March 6, 2001 The Pour-El and Richards result is for a worst case setting. It's been shown that there's no difficulty "on the average". This
is not unusual. For example, problems typically
suffer the "curse of dimensionality"
in the worst case. If one settles for a stochastic
assurance (Monte Carlo, for example) the curse
is vanquished. The bad result is just an artifact
of insisting on certainty. From: Cliff Pickover Date: March 6, 2001 As a general background to Edge readers, if they feel that only flesh and blood can support consciousness, then life would be very difficult in the Final Days when the universe expands and cools and does not contain water nor much energy. But to my way of thinking, there's no reason to exclude the possibility of non-organic sentient beings in the final diffuse universe. I call these beings Omega creatures. If our thoughts and consciousnesses do not depend on the actual substances in our brains but rather on the structures, patterns, and relationships between parts, then Omega beings could think. If you could make a copy of your brain with the same essential structure but using different materials, the copy would think it was you. More specifically addressing Freeman Dyson's essay, Freeman writes "If we are partly analog, the downloading of a human consciousness into a digital computer may involve a certain loss of our finer feelings and qualities." I would enjoy hearing him expand on this subject. For example, if I were to digitize an analog LP record at very high resolution, would I really have to lose any of its "finer qualities?" Perhaps the *playback mechanism* for the LP record affects it sounds, but it seems to me I have captured all of the LP record's qualities, and someday, given a good playback mechanism, it would sound just as beautiful. Perhaps we should even say that a digital capture of an LP record, even today, is indistinguishable in any "meaningful way" from the LP record in terms of the music's "finer qualities," our perception of the music, and the feelings the music evokes. I would also enjoy hearing Freeman expand on his sentence, "If the system could live forever, the temperature would ultimately become much lower than the energy-gap, and the states above the gap would become inaccessible.... It would be... dead." However, if the amount of energy in the universe asymptotically approaches zero, it will never reach zero. Is it possible that the universe will never reach a condition in which ALL the states of of the components of the living system become unreachable? Is it possible that there will be at least some of the states made possible via the vacuum fluctuations, where the overall universe's energy is arbitrarily close to zero but locally there may be variations allowing transient existence — not so different than what we all have now, transient existences. Even if this state would correspond to a person in a coma who is not fully conscious, we would still call this person "alive." And with life, there is always a hope, even if very slim, of resurrection and rescue from beings in parallel universes or from other dimensions. From: George Dyson Date: March 6, 2001 When I heard that Freeman's Edge question was "Is life analog or digital?" I was intrigued, because, as Freeman so eloquently argued in *Origins of Life* (1986) the answer is "both".
Assuming Freeman's model whereby life-as-we-know-it
originated as the result of a digital parasite
incorporated into the analog metabolism of its
original host, the time-without-end question is
whether we can now slowly exterminate (or at least
permanently archive) the parasite without killing
the host. Seems to me the answer is yes. Back
to "IS
LIFE ANALOG OR DIGITAL?: Question for Edge
discussion group from Freeman Dyson" |
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