Let me give you just two quotes.

1. "What is an analog computer?

Simply, an analog computer is a computing device that has two distinguishing characteristics:

1. Performs operations in a truly parallel manner. Meaning it can perform many calculations all at the same time.

2. And operates using continuous variables. Meaning it uses numbers that that change not in steps, but change in a smooth continuous manner.

By constrast, a digital computer can only perform sequential (one at a time) operations, and operates on discrete (noncontinuous) numbers. "

http://www.cowardstereoview.com/analog/

2. "An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. In contrast, digital computers represent varying quantities symbolically, as their numerical values change. As an analog computer does not use discrete (exact) values, but rather continuous (approximate) values . . ."

http://en.wikipedia.org/wiki/Analog_computer

I dont think an analogue computers needs to do parallel computations. It may often be the case, but a slide rules is a good example of an analogue computers that does single operations.

Otherwise I agree with Lev. Abacus and difference engine are mechanical but numbers are represented by discrete digits, so they are digital.

Vladimir, it's good to see you in the contest and I congratulate you on a clear and well illustrated essay.

You say that if the message we perceive is distorted then we cannot assume we have the correct answer. To some extent yes but eventually as more information is gathered our certainty increases.

For example, in your elephant picture the blind observers must have been unlucky to find things in just the right places to make it seem like they were touching an elephant. If they carry on they would soon find that the parts do not join up. We can never be absolutely certain but we can increase our certainty to a higher degree. Isn't that good enough?

In Einstein's original formulation of relativity the observer played a role, but when Minkowski reformulated it as geometry the observer was no longer needed. People have tried to reinterpret quantum mechanics to get ird of the observer but without success, yet the world was here before any observers. Was that history an illusion of the observer?

    Lev you are right I should not have used the term analog in reference to the soroban. I have been in Japan too long - here older people who do not use email and the Internet laughingly say of themselves that they are "analog". I guess the term came into use this way because of digital watches and analog ones with hands. I hope my meaning was otherwise clear that the physical bead (it) and the abstract number (information of sorts) were equivelant.

    Thanks Philip the slide rule would be analog!

    Thanks Philip Of course you are right; the blind men needed to have known what an elephant was in order to reach their conclusion from the peculiar placement of the onjects they touched. And yes our knowledge does increase concerning smaller and smaller details. My feeling was that the theories should somehow gain sharper focus and unity accordingly.

    My objection to Special Relativity is that the assumption of a constant speed of light made observation absolute and the universe (space and time) relative. This was unnecessary- space and time could have stayed absolute but measurement (clock rate, not time, and length of measuring rods, not space) relative and subject to physical Lorentz transformations. In QM the measurement can affect the sytstem randomly, but that does not mean the system was random before the measurement. Hope this makes sense!

    Vladimir,

    "I hope my meaning was otherwise clear that the physical bead (it) and the abstract number (information of sorts) were equivelant."

    Unfortunately, I can't agree with that. And the reasons for the disagreement are not found in today's physics, but in the area of pattern recognition. The reason is related to the distinction between the class of actual objects (e.g. a class of stars) and its informational representation. It appears that without having a separate "informational" class representation ("description") that is responsible for object generation, it is impossible to justify the regularity, or stability of classes of objects, i.e. why the new stars have the same structure as some of the previous stars, and it seems also impossible to justify/explain induction. (Of course this goes back all the way to Plato and Aristotle.)

      That was Loretnz's view of course. It works but requires a special reference frame that you can't detect. Poincare understood relativity a bit better but still hald a conventionalist view where he thought it was right to choose a reference frame by convention because that is the simplest view. Perhaps that is nearer your position. Nothing wrong with that way of thinking, it is just not the modern view.

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      Vladimir

      "Just today someone told me epistemology is the branch of philosophy concerned with knowledge"

      I would not worry about that, philosophy is a complete waste of time. All you have to understand is that physical existence is all that we can potentially know. We can only know what it is possible for us to know, and we cannot externalise ourselves from existence in order to ascertain what it 'is'. And knowing is based on a physical process, ie we receive physical input, which is commonly known as seeing, hearing, feeling, etc. Stick with common sense.

      Paul

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      Lev

      Physically, there is no such state as continuous. Or at least to be continuous would mean the same state perpetually. For difference to occur there must be discreteness (ie change by steps)

      Paul

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      Vladimir

      Bah, you should have not have said that and set me off!

      Leaving aside the fact that SR is not what generally people think it is, the thinking in Einstein which supposedly substantiates the concept of relativity does not involve observation. Because there is no light available for potential observers to observe with. You find me some. Lightening will not do it, unless you want your eyes burnt out. The point being that his second postulate is irrelevant, because he did not use it as defined. All Einstein did was utilise a constant by which to calibrate distance and duration. And for want of something and because he thought this accommodated observation, he described it as light. But it was just a constant, it could have been anything, and it is not observational light. So this whole exercise, including hs own efforts, in squaring light constancy with rate of change is a complete waste of time, because the problem was never there to begin with.

      Space and time, ie the rate at which reality alters, are absolute, it occurs independently of us, and definitively so. By conflating existence and the representation thereof (ie light), in failing to allow for observation, Einstein shifted the real time differential which is in the receipt of light from that to the other end of the process, ie deeming it to be a feature of existence itself. This incorrect presumption of indefiniteness is carried through into QM. Measurement cannot "affect the sytstem randomly", or indeed in anyway whatsoever, because to be able to measure something it has already occurred. Apart from which is observing you receive, ie interact with, light, not what occurred. All this nonsense about observers, etc, is just a device to try and rationalise out the fundamental flaws in the theories.

      Paul

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      Lev

      This distinction is false. Every actual object is different from every other actual object (leaving aside that physically there is no such thing as object, but a sequence of physically exisent states which appears to be an object, because certain superficial defining physical features persist over time). So one cannot actually have a 'class', or only of one state

      Its "informational representation" is just another way of describing its superficial characteristics. Physically nothing is the same as anything else. At a higher level of conceptualisation, one can discern similarities, but this has nothing to do with 'information'. Indeed, what this concept actually relates to physically, is a moot question.

      Paul

      Paul,

      I'm very sorry that you disrespect you *most powerful* (informational) ability to recognize patterns, e.g. to recognize a cat you haven't seen before as a "cat".

      Philip

      I wonder if there is a sound mathematical analysis along the lines you describe for Relativity sans the constant speed postulate? I know that some have used doppler wave descriptions of such scenarios. One of them is the late Gabriel LaFrenier whose website was only saved from oblivion by the Wayback Machine on Internet Archives. I wish fqxi will host this invaluable collection of great ideas. In my own analysis (sadly still qualitative) I am convinced that all the results of SR will come out in an absolute discrete ether with a maximum speed c but not necessarily constant.

      Paul, I wish I had the stamina and ability to explain my views on the observer issue in SR better than I already have, and to respond to your other points inasmuch as I understand them. I will now proceed to your essay page where doubtless exchanges such as the one here with Lev will be given full reign.

      Best,

      Vladimir

      Lev

      The word "Information" is loaded with many kinds of meaning. One of them as you point out is the philosophical one you explained in the Platonic tradition. I was treating it in a more modern Shanonic sense as a mathematical representation that can be manipulated in computers.

      Vladimir, still, from a 'conceptual' point of view, it is more productive to keep the two separate. But, of course, it's your essay. ;-)

      Vladimir

      But sadly they didn't. So I still await proof that there is observation in Einstein, how observation relates to physical circumstance, or indeed response on other areas of difference. Incidentally, when others started quoting Einstein at me in an attempt to demonstrate that what I was saying was flawed, I put up the first 24 paras of an abridged paper on why he was wrong on my essay blog.

      Paul

      Lev

      The point is, as I have pointed out in commentary on your own blog, there is no such thing, physically, as 'cat'. And physics is supposed to be considering what physically occurs. Cat, is a conceptualisation of physical existence at a much higher level than what occurs. That is, we deem cat on the basis of certain superficial physical attributes, and then assert that this conceived 'thing' persists in existence so long as those attributes pertain. Indeed, we even allow the attributes to alter at that level of conception, but still assert its continued existence. Which is a contradiction. But is rationalised by the concept that 'it' has changed.

      So even at that level we ignore what is actually happening, which is understandable in order to get on with ordinary life. But physically, cat is a sequence of definitive discrete physically existent states, which are such that at a much higher level of conception manifest certain similarities. And physics needs to understand this if it is to make proper progress, ie it needs to understand how what it is investigating (ie physical existence) occurs. In other words, any given cat is not physically the same at different times, and no cat is the same as another, except at an artificially conceived level.

      Paul

      Vladimir

      "I wonder if there is a sound mathematical analysis along the lines you describe for Relativity sans the constant speed postulate?"

      But the second postulate was not deployed as stated, it was just a constant, which happened to be an example of light. There is no relativity in physical existence. At any given time, something occurs. The relativity, or more precisely, time differential, is in the receipt of a physically existent representation of that occurrence (ie in the case of sight-light), which leaving other factors aside, fundamentally revolves around relative spatial positon. There is no observation in Einstein, because there is no observational light, occurrence and representation thereof, were conflated, so this time differential in the receipt of light, which does occur, was been attributed to existence. This simple mistake was counterbalanced by another simple mistake, ie his failure to understand timing (after Poincaré) which resulted in the creation of an extra layer of time (ie "common time").

      Paul

      Paul, by the way, a stone today is different from the same stone tomorrow, which is true for most objects/processes in Nature. But that does not mean that "there are no such thing, physically". This is an absolutely typical mode of "physical existence".