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Hardware Hacking Build Technology

Hydraulic Analog Computer From 1949 184

mbone writes "In the New York Times, there is an interesting story about a hydraulic analog computer from 1949 used to model the feedback loops in the economy. According to the article, 'copies of the 'Moniac,' as it became known in the United States, were built and sold to Harvard, Cambridge, Oxford, Ford Motor Company and the Central Bank of Guatemala, among others.' There is a cool video of the computer in operation at Cambridge University. I remember that the Instrumentation Lab at MIT still had an analog computer in its computer center in the mid-1970s. Even then, it seemed archaic, and now this form of computation is largely forgotten. With 14 machines built, it must have been one of the more successful analog computers — a supercomputer of its day. Of course, you have to wonder if it could have been used to predict our current economic difficulties."
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Hydraulic Analog Computer From 1949

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  • by Red Flayer ( 890720 ) on Wednesday June 03, 2009 @01:26PM (#28198181) Journal
    Dammit. Couldn't resist.

    Of course, you have to wonder if it could have been used to predict our current economic difficulties.

    No, you don't have to wonder that. The current economic difficulties were easily predicted by many.

    The problem was that the people with any kind of ability to stop the conditions that led to the current situation were those who profited most from those conditions. Not a good recipe for prevention.

  • by shadowofwind ( 1209890 ) on Wednesday June 03, 2009 @01:35PM (#28198321)

    If lots of people are extracting money from the system and not contributing real wealth, then there will be problems. Money has complicated dynamics, but its not magic. People who make a living shuffling numbers around in spreadsheets are providing a useful service that makes the system more efficient. But only up to a point. Few people believe greed is a vice anymore, hence certain results follow.

  • by langelgjm ( 860756 ) on Wednesday June 03, 2009 @01:42PM (#28198411) Journal
    Yeah, the WP article is much more informative than the video. The guy in the video spends the first minute kind of standing there saying "now what I'm going to do..." without actually doing anything. The next two and half minutes aren't much better.
  • by Anonymous Coward on Wednesday June 03, 2009 @01:44PM (#28198453)

    "What the hell can go wrong with lending $500,000 for a house to someone who's salary is only $20,000 per year?" - Brainless Banks

  • by caffeinemessiah ( 918089 ) on Wednesday June 03, 2009 @01:47PM (#28198511) Journal

    There is a serious flaw in thinking that computers can accurately model macroeconomics, or predict systematic collapses, any better than commonsense and basic logic can

    It might not be an accurate descriptive model (one that describes reality), but discriminative models are very useful -- not to predict systematic collapses, but to discriminate irrational behavior. Computers step in when your response time has to beat efficient markets. You could be a common sense and logic genius, but you can only apply those rules and react in so much time, and computers will always beat you for speed at applying your own rules. So it's a different kind of crutch, and just like a crutch, it can help you walk better, not walk for you.

    I might have digressed from TFA, but this is /.

  • by Brett Buck ( 811747 ) on Wednesday June 03, 2009 @01:49PM (#28198543)

    1998, you mean. There was a reason they had all those banking rules developed over centuries, You can't just wipe them out with a stroke of a pen, and expect no consequences.

            Brett

  • by Anonymous Coward on Wednesday June 03, 2009 @01:51PM (#28198567)

    Modeling the current economic woes? Just attach a balloon in the appropriate place.

    When it bursts, there'll be a big mess to clean up and it'll take a while.

  • by Trepidity ( 597 ) <delirium-slashdot@@@hackish...org> on Wednesday June 03, 2009 @01:57PM (#28198655)

    I think it's not so much that it can't in theory be modeled, as that in practice it's extremely hard---much harder than modeling the weather, which we can barely do accurately out to 5 days. There's somewhat of a gap in expectations when you go from high-level qualitative descriptions of phenomena, like hurricane experts discussing trends in intensity and formation basins, to an implemented, detailed computational model that purports to simulate what "really" happens. The 2nd one usually diverges extremely quickly from what actually does happen, because these sorts of nonlinear systems are very sensitive to slight errors in the model or its initial conditions.

    That's fine, as long as people understand its use and limitations; but there's a tendency, especially among the only-sort-of-technical folks who are involved in a lot of areas of business and economic policy, to trust these computer models as more than they are, as if the fact that a "computer simulation" told you it makes it some sort of neutral third-party truth that represents the state-of-the-art in guessing what will happen.

  • by fastest fascist ( 1086001 ) on Wednesday June 03, 2009 @01:59PM (#28198679)
    It doesn't take a computer to predict what happens. You get a boom, people spend money, they overspend, you get a crash. Repeat. The details vary, but the basic pattern seems pretty clear.
  • by petermgreen ( 876956 ) <plugwash.p10link@net> on Wednesday June 03, 2009 @02:31PM (#28199071) Homepage

    Indeed, when it comes to anything safety crtical KISS is a good principle to follow as it will make it much easier to ensure safety.

  • by Tokolosh ( 1256448 ) on Wednesday June 03, 2009 @02:33PM (#28199093)

    All you need is the Micawber Principle:

    "Annual income twenty pounds, annual expenditure nineteen pounds nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery."

    From David Copperfield, by Charles Dickens

  • by inviolet ( 797804 ) <slashdot&ideasmatter,org> on Wednesday June 03, 2009 @02:40PM (#28199173) Journal

    Probably not, but Byron Dorgon Predicted this trouble in 1995 when teh derivatives markets starte to get noticed and again in 1998 when the "securities modernization act" was passed, deregulating the banks, insurance companies and investments firms.

    As we say in Economics circles: "Yes, the man is a genius: he predicted 9 of the last 3 recessions!"

  • by JesseMcDonald ( 536341 ) on Wednesday June 03, 2009 @02:52PM (#28199307) Homepage

    It's worse than that, actually. Weather prediction is at least based on physical processes, which, allowing for some minor concessions to quantum mechanics, are based on fundamental particles which follow deterministic rules. Given all the initial conditions and sufficient computing power you could accurately simulate what the weather will be at any point in the future. Moreover, you can use simulations to predict how that future weather will change in response to deliberate artificial influences; weather doesn't have goals of its own, and won't actively resist attempts to control it.

    Economics isn't like that. The "fundamental particle" of economics is people, and people are adaptive. Under many conditions is it possible to predict how they will behave--assuming rational self-interest (i.e. sanity) and decent psychological models of their personal value scales--but all that breaks down when someone attempts to use the models to control the outcome. At that point you have a competition between the people being studied, who seek to achieve their original goals and thwart any attempt at outside control, and those seeking to do the controlling. As with any long-running competition between creative individuals, the outcome is impossible to predict with any degree of accuracy.

  • by nedlohs ( 1335013 ) on Wednesday June 03, 2009 @03:14PM (#28199581)

    Could predict todays our current economic difficulties and spend 18 minutes playing with the abacus.

  • Modern Replacement (Score:3, Insightful)

    by Nom du Keyboard ( 633989 ) on Wednesday June 03, 2009 @03:38PM (#28199875)
    Seems to me that this could be replaced today with an Excel spreadsheet - and no I'm not being facetious.
  • by mcrbids ( 148650 ) on Wednesday June 03, 2009 @04:09PM (#28200339) Journal

    Often, digital computing is clumsy, awkward, and overly precise.

    A good example of this is in Aviation. Pilots are still trained to use the E6B Flight computer [wikipedia.org] which is really a glorified slide rule.

    When you are estimating fuel consumption, and figure you'll probably use about 11.5 GPH for 3 1/3 hours, it's not important to know any more accuracy than perhaps to a gallon or so, since reality will always be a bit different than your calculations, anyway. You don't need to be exactly precise on your degrees of heading, and when you are computing weight & balance, it's stupid to calculate your moment to the 4th decimal place.

    Knowing how to use an E6B, you can get calculations in a second or two with a single hand that are "good enough" - and that's important when you're flying an airplane in turbulence while trying to stay on top of busy ATC calls in a heavily trafficked area. You can't even enter the first of 3 or 4 digits into a digital calculator in that time, and you'd have to use two hands. (Frequently, when flying, your hands are both occupied and you're steering with just your feet)

    Digital isn't always better.

  • by JesseMcDonald ( 536341 ) on Wednesday June 03, 2009 @04:48PM (#28200953) Homepage

    I never said humans were random. I also wasn't assuming that humans always pick their goals rationally. "Rational self-interest" doesn't mean that humans are completely rational, but rather that given subjective (and possibly irrational) goals, and a possibly inaccurate and certainly incomplete subset of the relevant knowledge, humans will tend to act in ways which appear likely to them to bring them closer to their goals. Anything else would be, as I said, the essence of insanity.

    I acknowledge that crowd behavior can be more predictable than individual behavior. I think you'll find, however, that even crowds are difficult to control deterministically over the long term, in part due to the ways in which individual contributors can influence the result entirely out of proportion to their apparent power and in part due to the effects of creative adaptation, which grow more pronounced over time. The system is far from random, but it is chaotic.

  • by Q-Cat5 ( 664698 ) on Wednesday June 03, 2009 @05:03PM (#28201207)
    There's a difference between mapping rules in a general fashion, and applying them to actual situations. Invariably, reality always has elements that differ from the model, and thereby make it inaccurate. This is why reductionism doesn't generally map back accurately to the big picture. Understanding a component is different from understanding how the component integrates into the whole, and how other components within the whole interact with, and alter, the component.

    Human behavior is very nearly impossible to accurately model at the individual level. You hear "I never would have expected him to do that" when people speak about their next door neighbors who go on homicidal rampages. Husbands or wives are shocked when the spouse that they've lived with for years or decades has an affair, buys a sports car, or has a second cup of coffee after dinner. Even crowd dynamics can be altered by incredibly subtle, and unpredictable, circumstances. (Someone in a crowded line says "He's got hairy wrists", someone else hears "He's a terrorist", and soon 8 are trampled to death in the ensuing panic.)

    Then, add people deliberately gaming the system into the equation. (i.e. someone else wants to steer the crowd in a different direction than your model would normally predict, perhaps even using your model to predict the best way to disrupt it.)

    Raw computing power just can't compensate for all the variables. At some point of hyper-precision, they become recursive anyway, and Gödel gets to have posthumous a laugh at your expense.
  • Fluidic Systems (Score:3, Insightful)

    by TheSync ( 5291 ) on Wednesday June 03, 2009 @05:23PM (#28201545) Journal

    I'm a fan of Fluidics [wikipedia.org], which can create analog or digital devices based on fluid flow.

    See this powerpoint [mit.edu] for a great history of fluidics.

  • by adolf ( 21054 ) <flodadolf@gmail.com> on Wednesday June 03, 2009 @09:18PM (#28204523) Journal

    And then the video just sort of ends, without the computer having, um, computed anything. The whole thing is about as entertaining and instructive as watching the skimmer on my swimming pool (except the skimmer might actually be more interesting).

    Does anyone have a better (or simply more-complete) moving-pictures demonstration of this remarkable machine?

  • by MSTCrow5429 ( 642744 ) on Wednesday June 03, 2009 @10:55PM (#28205213)
    This is inaccurate. I disagree with the chronic and consistent misuse of computer modeling, such as within economics or climate modeling, where the variables are assumed to exist without any rational basis, empirical history is disregarded as being a nuisance to the desired results, and past mistakes in the model are ignored or covered up. I have no problems with computer modeling in designing, say, a car, airplane, or bridge.

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