Soupie
Paranormal Adept
Edge.org is becoming quite the rabbit hole for me. Wow. I stumbled across the following article and insightful comments:
IS LIFE ANALOG OR DIGITAL? | Edge.org
IS LIFE ANALOG OR DIGITAL? | Edge.org
IS LIFE ANALOG OR DIGITAL?
Freeman Dyson: ... Silicon-based life and dust-based life are fiction and not fact. I use them as examples to illustrate an abstract argument. The examples are taken from science-fiction but the abstract argument is rigorous science. The abstract concepts are valid, whether or not the examples are real. The concepts are digital-life and analog-life. The concepts are based on a broad definition of life. For the purposes of this discussion, life is defined as a material system that can acquire, store, process, and use information to organize its activities. In this broad view, the essence of life is information, but information is not synonymous with life. To be alive, a system must not only hold information but process and use it. It is the active use of information, and not the passive storage, that constitutes life. ...
Steve Grand responds: When it comes to life, we see the analogue/digital distinction disappear completely, to be replaced by the spectrum of forms of encoding it really is. Take a nerve signal: at a theoretical level we can treat an action potential as a differentiated square wave, i.e. a spike of infinitesimal width and infinite height ‹ the ultimate in digital. But in practice the cell membrane takes a finite time to transit between polarised and depolarised states and so forms a smooth (if sharp) curve ‹ this is an analogue change (discrete at the quantum level). But then again, there are only two significant states, polarised and depolarised, so we're back to a digital system. And yet what really matters is the choice of encoding scheme, which for the majority of neurons seems to be frequency modulation, and so the true signal is analogue and can vary continuously. Mind you, two spike peaks can only vary in distance by a whole number of molecules, and so this analogue signal is really discrete... Argh!
Steve Grand responds: When it comes to life, we see the analogue/digital distinction disappear completely, to be replaced by the spectrum of forms of encoding it really is. Take a nerve signal: at a theoretical level we can treat an action potential as a differentiated square wave, i.e. a spike of infinitesimal width and infinite height ‹ the ultimate in digital. But in practice the cell membrane takes a finite time to transit between polarised and depolarised states and so forms a smooth (if sharp) curve ‹ this is an analogue change (discrete at the quantum level). But then again, there are only two significant states, polarised and depolarised, so we're back to a digital system. And yet what really matters is the choice of encoding scheme, which for the majority of neurons seems to be frequency modulation, and so the true signal is analogue and can vary continuously. Mind you, two spike peaks can only vary in distance by a whole number of molecules, and so this analogue signal is really discrete... Argh!
Much the same mess and mix of mechanisms applies to DNA too. ACTG may be digital, but genes are also encoded by the folding structure of DNA, RNA and the relevant enzymes, so although the resultant protein's amino acid sequence is defined digitally, the particular physical form it takes on (proteins can often fold up in many different ways, with different properties) depends on much less clear-cut factors.
The idea of digital might seem like a neat trick to us humans, who've only just discovered it. But nature simply isn't impressed either way. ...
So "is life digital or analogue?" is surely therefore a non question, since the word "is" implies that it's a practical question, not a theoretical one? "Could life be digital or analogue" is a theoretical question (although it's a practical one for people like me, who work in Artificial Life). But the answer here is surely: it doesn't care. Whenever a network of cause and effect is capable of sustaining itself, it will. Perhaps it now boils down to how discrete such information flows need to be in order to be self-sustaining, and my hunch here is that highly discretised signals (like ACTG) are an advantage but not a necessity.
Jordan Pollack responds: ... 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. ...
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.
So "is life digital or analogue?" is surely therefore a non question, since the word "is" implies that it's a practical question, not a theoretical one? "Could life be digital or analogue" is a theoretical question (although it's a practical one for people like me, who work in Artificial Life). But the answer here is surely: it doesn't care. Whenever a network of cause and effect is capable of sustaining itself, it will. Perhaps it now boils down to how discrete such information flows need to be in order to be self-sustaining, and my hunch here is that highly discretised signals (like ACTG) are an advantage but not a necessity.
Jordan Pollack responds: ... 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. ...
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.
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