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Science

MIT Physicists Have Finally Cracked Overhand Knots 74

Posted by samzenpus from the boyscout-approved dept.
An anonymous reader writes: Knots are indeed a relatively ancient art, a technology developed across centuries of trial and error and some very old, intuitive notions of symmetry and elegance. (The more 'ugly' or random a knot looks, the less likely it is to function well.) The basic physics and mechanics of knots are, however, relatively unstudied scientifically. If a knot works then it works—what more is there to ask? Quite a bit, it turns out. In a study recently accepted for publication in the Physical Review Letters, engineers at MIT and Pierre et Marie Curie University in Paris offer a new fundamental theory of knots based on relationships between topology, the mathematics of spatial relationships, and the basic mechanics of friction and pliability.
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MIT Physicists Have Finally Cracked Overhand Knots More

MIT Physicists Have Finally Cracked Overhand Knots

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  • Maybe (Score:1)

    by Anonymous Coward

    now they can tie their own damn shoelaces!

    • Re: (Score:3)

      by gfxguy ( 98788 )

      I learned, at age 47, I'd been tying my shoelaces wrong, so I'm amazed at what we can find out in mundane things like studying knots.

      In case anyone cares - I learned if the starter knot goes left over right, the finishing part needs to go right over left. If you do left over right again, it's not strong and comes untied. As soon as I learned this and switched, I never had a shoelace come undone.

    • Re: (Score:1)

      by Anonymous Coward

      now they can tie their own damn shoelaces!

      Shoelaces are stone-age technology. Some of us use 20th century technology - velcro!

  • Unintended consequences (Score:5, Funny)

    by Calydor ( 739835 ) on Friday September 11, 2015 @03:25AM (#50501071)

    And to think this research project started when a college undergrad typed, "How to get married" into Google and learned that he had to tie the knot.

  • Not much practical use, yet. (Score:5, Interesting)

    by kooky45 ( 785515 ) on Friday September 11, 2015 @03:57AM (#50501137)
    They've studied how much force it takes to tighten a very simple overhand knot with various numbers of turns and developed mathematical theory that is good at predictions. Whilst it's interesting, most knot use is probably more interested in the opposite case of how much force is necessary to untie a knot, or how much force a knotted rope can withstand, or which knot configurations are comparable in strength. That'll take a much bigger leap in research but this is a good start.

    • Re:Not much practical use, yet. (Score:4, Interesting)

      by Amouth ( 879122 ) on Friday September 11, 2015 @04:45AM (#50501221)

      all i care about is single and double bights. they can figure out the math, i'll use what i know is safe for what i'm doing.

      now if they figure out that something that is currently believed to be safe has a previously unknown failure method, then i'd be interested.

    • Re:Not much practical use, yet. (Score:5, Interesting)

      by hawkinspeter ( 831501 ) on Friday September 11, 2015 @07:30AM (#50501545)
      Knots may be far more interesting and useful than just their use with ropes. There was an unexpected connection discovered between knot theory and Burnside groups: http://www.ncbi.nlm.nih.gov/pubmed/15576510/ [nih.gov]

      By having a deeper understanding of knot, we may get a better handle on aspects of group theory which has very close connections to quantum mechanics and string theories. So, whilst you may argue about whether that can be considered "practical", it may lead to a deeper understanding of the matter that we're made of.

      • Re: (Score:1)

        by Anonymous Coward

        You're talking about mathematical knot theory, which has a lot to do with combinatorics and group theory. This is talking about studying the physics of actual knots, as in friction and forces involved, which is rather distinct from mathematical knot theory usually (studying a particular knot often, instead of categorization and equivalence of different knots). This is very much practical orientated research, and failure for this particular kind of research to find something useful for tying actual knots i

      • I was interested in this article because I thought it was on knot theory and practical applications of it. If you (the dear reader) has some time, the book 'The Knot Book' by Colin Adams is a nice introduction to knot theory. Really fascinating, and will get you thinking in terms of topology. And, like much mathematics that started by just thinking about something interesting from a mathematcial point of view, it turns out to be useful in a number of areas.

        That said, this is totally not about knot theory

      • By having a deeper understanding of knot, we may get a better handle on aspects of group theory which has very close connections to quantum mechanics and string theories.

        So by studying knots we'll better understand strings? Science!

    • Whilst it's interesting, most knot use is probably more interested in the opposite case of how much force is necessary to untie a knot, or how much force a knotted rope can withstand, or which knot configurations are comparable in strength.

      I use knots for rock climbing a combination of strength + ease to untie + safety are important to me. The annoying thing with a figure of eight (the standard climbing knot for attaching a rope to a harness) is that it can be quite hard to untie after falling on it. If you do any sports climbing - and push your limit, you will do lots of falling, so i use bowline.

      The issue with a bowline is it can be unsafe if not tied correctly and with some extra redundancy, even then some people still consider it too dang

      • Any stopper knot tied incorrectly can be dangerous. As can using the wrong type, for example, a reef with unequal strain as it can capsize.

        People blaming a bowline for being unsafe is just them being unable to tie it correctly. Arguably, an incorrectly tied bowline isn't a bowline...

        • Re: (Score:2)

          by tomxor ( 2379126 )

          Arguably, an incorrectly tied bowline isn't a bowline

          You mean without a stopper? Yes I don't consider a bowline complete without it, and the climbing related deaths i have heard of are all due to a lack of or poorly tied stopper

          With a bowline I tie a generous stopper with enough end to thread back through the bottom of my harness making the possibility of the end slipping through the stopper very low. I guess with a figure of eight you still have a pretty safe self tightening knot without a stopper - or even half a figure of eight, so maybe that's why people

      • The annoying thing with a figure of eight (the standard climbing knot for attaching a rope to a harness) is that it can be quite hard to untie after falling on it.

        Try going one turn beyond the figure-of-8 to the "figure-of-9" (there are other names). This has the strength of the fig-8, it's harder to jam after heavy loading, and it's pretty easy to tie safely (failure modes include the fig-10 and the fig-8, both perfectly fine knots.

        Many cave rescue teams recommend the fig-9 for main belays, and particular

        • Re: (Score:2)

          by tomxor ( 2379126 )

          The annoying thing with a figure of eight (the standard climbing knot for attaching a rope to a harness) is that it can be quite hard to untie after falling on it.

          Try going one turn beyond the figure-of-8 to the "figure-of-9" (there are other names). This has the strength of the fig-8, it's harder to jam after heavy loading, and it's pretty easy to tie safely (failure modes include the fig-10 and the fig-8, both perfectly fine knots.

          Interesting, thanks!

          • The Alpine butterfly is really well worth knowing.

            Memory workign overtime ... "Life on A Line [lifeonaline.com]" used to be a very important resource - I remember having conversations with the author when he was writing it he was asking for peer review form most of the caving population of the UK. Unfortunately,

            From 01 Jan 2015 the eBook version of Life On A Line will no longer be available. Changes to European tax law have created a complex series of additional costs that make the sale of eBooks impossible at a reasonable

  • Empirical Data (Score:1)

    by Anonymous Coward

    >If a knot works then it works—what more is there to ask? Quite a bit, it turns out.

    People -have- collected empirical data on many knot types with many different materials, compared relative knot strengths, susceptibility to jamming, ease of untying, seaworthiness, suitability for climbing/rescue/lashing/towing/packaging, etc. Why know why certain knots are weaker than others (e.g. sharp bends).

    It's not as if people don't study this stuff.

  • funnily enough... (Score:4, Interesting)

    by ihtoit ( 3393327 ) on Friday September 11, 2015 @04:16AM (#50501171)

    I was just talking to the wife about how I learned knotting and how to use knots to pull two threads together with minimal effort (the simple start-from-the-middle-and-work-towards-the-ends method) as I was tying a cabin case onto a flatbed bike truck (don't ask). Basically I learned by trial and error, where threads had to go for the best knot for a given situation. Now I can tie just about any knot you show me a photo of, but I'm buggered if I could actually *name* many.

  • The researches just couldn't be arsed to look up The Ashley Book of Knots. I used to teach Abseiling, and we had to know the strengths and attributes of various knots.

    • Re:Actually, they didn't learn anything new. (Score:5, Insightful)

      by Anonymous Coward on Friday September 11, 2015 @04:26AM (#50501183)

      The researches just couldn't be arsed to look up The Ashley Book of Knots.
      I used to teach Abseiling, and we had to know the strengths and attributes of various knots.

      Scientific knowledge proceeds from the particular to the general. Empirical data is important, but having a general theoy with predictive power even moreso. So no, what these researchers are doing is definitely a novelty. The work goes way beyond just cataloging the different kinds of knots (and their mechanical properties).

    • Re: (Score:1)

      by Anonymous Coward

      That's like saying Darwin couldn't be arsed to look up My Big Book of Animals. Just because some domain is partially catalogued doesn't mean we understand the domain, and yes, figuring out the principles behind everything that's listed in that book is better than merely reading the book.

    • Ashley is a fantastic resource for learning which knots work for a task (although it has notable flaws when it comes to certain modern synthetic ropes...would love to see someone update the text), but it does not teach you how and why those knots work.

      These knots have all been thoroughly tested. We know their breaking strength, we know their ease of untying, etc. But I don't think anyone knows how to predict the forces besides testing. If I designed a new knot, would anyone be able to model the attribu

  • I would read TFA... (Score:3)

    by Viol8 ( 599362 ) on Friday September 11, 2015 @04:33AM (#50501195) Homepage

    .. but I'm a bit tied up at the moment.

  • Correlation with other types of bonds in nature. (Score:5, Interesting)

    by deviated_prevert ( 1146403 ) on Friday September 11, 2015 @04:35AM (#50501203) Journal
    If we define a knot as being a configuration which simply joins strings together at a position is space then the problem of how things work and in what sequence becomes more clear. For instance if you can visualize a blood knot [animatedknots.com]or a spider hitch or bimini twist [netknots.com]in your mind then you can see the points at which the friction occurs and how the knot is lock stopped and how it works. For an experience fisherman this can become fairly easy but only with practice, for someone who never ties complex knots or conceives of how they might fail this is a very difficult task.

    It will be really interesting to see the mathematical advances that come from the study of more complex knots. It is altogether possible that new algorithms that will apply to other disciplines will emerge from the study being undertaken. We might even discover insights into the knotting of proteins and other chains that produce strings that knot. What works at the microscopic scale down to the molecular level will work completely differently on the larger scale and that difference should be something that can be quantified. Knots are a fascinating study and even the primitive human was fascinated by them, they were one of the first essential skills that the human race developed. Without the study of knots we would not have clothing is the first thing that comes to my mind. Who knows where the study of knots on a mathematical level can lead us.

    • For instance if you can visualize a blood knot [animatedknots.com]or a spider hitch or bimini twist [netknots.com]i

      Woah, someone in those links is already using Live Photos. Wild!

    • Even more importantly, maybe they'll discover why headphone cables get so tangled up, and learn how to design new tangle-resistant headphones.

    • For instance if you can visualize a blood knot or a spider hitch or bimini twist in your mind then you can see the points at which the friction occurs and how the knot is lock stopped and how it works. For an experience fisherman this can become fairly easy but only with practice, for someone who never ties complex knots or conceives of how they might fail this is a very difficult task.

      Another fisherman put it best. There are basically two types of knots. Stop knots, where loops press up against each oth

  • Well studied in math (Score:2, Informative)

    by Carewolf ( 581105 )

    It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

    • It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

      Topological knots are closed and not generally useful for understanding characteristics of physical knots. For one thing, it's impossible even to talk about the strength of a closed knot because there are no ends to pull on. This work is mathematical modeling of physical, open, knots and their useful characteristics.

      • It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

        Topological knots are closed and not generally useful for understanding characteristics of physical knots. For one thing, it's impossible even to talk about the strength of a closed knot because there are no ends to pull on. This work is mathematical modeling of physical, open, knots and their useful characteristics.

        I didn't take the course myself, but the academic posters and articles I have seen were all open.

        • It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

          Topological knots are closed and not generally useful for understanding characteristics of physical knots. For one thing, it's impossible even to talk about the strength of a closed knot because there are no ends to pull on. This work is mathematical modeling of physical, open, knots and their useful characteristics.

          I didn't take the course myself, but the academic posters and articles I have seen were all open.

          The posters and articles were open? Or the knots? By "closed" I mean that the "rope" has no ends; it's a loop. This means mathematical knots can't be "tied" or "untied".

          • It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

            Topological knots are closed and not generally useful for understanding characteristics of physical knots. For one thing, it's impossible even to talk about the strength of a closed knot because there are no ends to pull on. This work is mathematical modeling of physical, open, knots and their useful characteristics.

            I didn't take the course myself, but the academic posters and articles I have seen were all open.

            The posters and articles were open? Or the knots? By "closed" I mean that the "rope" has no ends; it's a loop. This means mathematical knots can't be "tied" or "untied".

            I meant it was real knots with strings with two ends.

            • It is well understood in math, because it is not physics or engineering, but knot theory is a mathematically field.. Seriously.

              Topological knots are closed and not generally useful for understanding characteristics of physical knots. For one thing, it's impossible even to talk about the strength of a closed knot because there are no ends to pull on. This work is mathematical modeling of physical, open, knots and their useful characteristics.

              I didn't take the course myself, but the academic posters and articles I have seen were all open.

              The posters and articles were open? Or the knots? By "closed" I mean that the "rope" has no ends; it's a loop. This means mathematical knots can't be "tied" or "untied".

              I meant it was real knots with strings with two ends.

              Cool. That's unusual, if that's what they were actually studying. Could also have been that someone just grabbed random pictures of knots to put on posters, etc.

  • Godwined in the headline? (Score:3)

    by tomhath ( 637240 ) on Friday September 11, 2015 @07:46AM (#50501583)
    Oh wait, he said *knots*

  • 1 knot = 1.852 km/hr

  • ... a bunch or researchers were paid to take some co-ed volunteers and practice shibari.

  • I see they tied themselves in knots over this.

  • turns out i've been tying my pretzels all wrong, that's why they all turn into crullers.

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