The Riddle of the Samurai Sword
For some reason I just remembered a simple little puzzle I was told about ages ago, so I thought I’d try it out here.
On certain trains in Japan, passengers are not allowed to enter a compartment with any piece of luggage which is too long or too wide to be placed in the overhead racks; any parcel or package with dimensions larger than 60 cm × 80 cm is forbidden. It is possible however to enter the carriage with a metre-long samurai sword.
How?
Answers through the comments box please…
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January 13, 2014 at 9:30 am
The diagonal !
A^2 + B^2 = C^2
January 13, 2014 at 9:47 am
Of what?
January 13, 2014 at 9:55 am
Of the 60cm by 80cm compartment.
January 13, 2014 at 9:59 am
Alternatively you could enter the compartment just wearing it ??
January 13, 2014 at 9:33 am
Diagonally?
That must be too obvious…
January 13, 2014 at 9:47 am
Diagonally in what?
January 13, 2014 at 9:57 am
I’m not playing any more *sulks*
January 13, 2014 at 11:20 am
Whilst a metre long object will technically fit diagonally between the opposite corners of a 0.8 m * 0.6 m rectangle, I suspect it’s easy to enter most places if you’re carrying a samurai sword and you look like you’re willing to use it.
January 13, 2014 at 11:57 am
Given your reaction to the suggestions of the diagonal, perhaps you’re looking for a different answer. Is the carriage divided into areas only some of which are compartments? So, for example, an old-fashioned first-class carriage would have a corridor where swords are allowed.
January 13, 2014 at 12:22 pm
you don’t enter the compartment … you stay in the corridor
January 13, 2014 at 12:26 pm
My only point is that in order to carry such a sword into the compartment, one would need first to purchase a case of dimensions 60cm by 80cm and then place the sword diagonally in the case. You can’t take the sword on its own because it would be considered too long. Those of you who remember the (3,4,5) triangle will have figured out that a rectangle of sides 60 and 80 will have 100cm along the diagonal.
January 13, 2014 at 12:36 pm
I’m surprised nobody has yet suggested swallowing the sword! 🙂
January 13, 2014 at 2:24 pm
Slowest way to commit harakiri
January 13, 2014 at 3:51 pm
And rather messy too. Of course, given the size of the carriage, ones kaishakunin might not be able to get their sword into the carriage as well.
January 13, 2014 at 3:06 pm
60 cm × 80 cm …………. x 100 cm maybe?
January 13, 2014 at 4:02 pm
Another solution: one could snap the blade in two, then it would fit!
January 13, 2014 at 6:50 pm
This non physicist has worked out the answer. Move the sword into the package at a speed approaching the speed of light and the length of the sword will reduce sufficiently for the sword to fit in the package. But I guess once it was a rest the sword would “expand.”
January 14, 2014 at 1:49 am
Incidentally, I saw several fine examples of the Katana (Samurai Sword) in the Tokugawa Art Museum on Sunday. The blades are about 70cm long, but the swords have long handles so they could be held in two hands. Other differences between the Katana and a European longsword such as a Toledo or Damascus sword, is that it is curved, single-edged, and rather slender.
January 14, 2014 at 3:00 pm
They are also made of two kinds of carbon steel with different carbon content; the cutting edge is made of the harder steel. This mixture of steels leads to the traditional hamon (the wavy line along the length of the blade), though many modern swords have a hamon that is etched onto the blade. The suka, or handle, is one piece and the blade slots into it and is held there by two pegs, traditionally made from bamboo (many are actually old bamboo chopsticks!). The better katana will have two pins showing that the steel goes a long way up the suka and improving the overall balance of the sword.
The differences in design between the katana and the European swords in part arises from the different way they are used. European sword fighting revolves around the thrust, whereas Japanese sword fighting revolves around the cut or slice. In fact, the business end of the katana is generally the last few inches of the blade near the tip (kissaki) The curvature of the blade assists in the physics of this by improving the angle of attack. Learning how to cut properly with a katana takes considerable time as they are very easy to bend out of shape, in fact they are relatively easy to snap in two if hit in the right way.
January 14, 2014 at 4:36 pm
Which combination of sword design and use would be more effective in a “mixed martial arts” contest?
Am I right in thinking that when these blades ore forged, the hot and pliable metal is repeatedly folded, producing cross-sections of the sort seen in some chaotic Hamiltonian transformation diagrams?
January 15, 2014 at 12:35 am
Interesting questions. What little I’ve seen of MMA (which I admit is not much) leaves me highly unimpressed, so I would say it would not make much of a difference if the combatants were MMA.
If one were considering a proper duel between someone proficient with a straight sword and someone proficient with a katana, then I really wouldn’t know. I did fence for a couple of years a few years ago, I’ve also worked extensively on Tai Chi sword forms and I now practice one of the traditional Japanese ryu. Each style and technique is very, very different (you even see this amongst the different European sword forms). My guess (and it’s only that, there are many factors involved) is that, all other things being equal, the person with the European sword and technique would come off worst.
When the blades are forged in the traditional way they are indeed folded many, many times in a form of annealing. Often, some carbon source is placed within the folds to alter the carbon content of the steel in certain regions. The classical furnaces where the ingots are made are quite fascinating and reveal that the smiths had a rather good knowledge of practical metallurgy. I’m not sure about the chaotic patterns, I can’t recall seeing an image of the cross section of a blade, but I imagine one would not be able to see the original folds, but I don’t really know.
January 15, 2014 at 10:16 pm
Adrian, I’d like to know why you reckon that a Samurai would beat (say) a Renaissance expert swordsman. I’m not disagreeing with you, but in MMA it’s not necessarily the most single-minded fighter who wins but the one whose chosen martial art has more answers. This is very technical stuff, as is swordfighting.
January 16, 2014 at 3:19 pm
Hi Anton,
Why would I put my money on the samurai? Largely out of 35 years of experience of different martial arts and fighting styles. All styles have their strengths and weaknesses, but one of the things I have found most impressive about the traditional ryu is their flexibility and rapid adaptability in technique. Given the large range of weapons, techniques and styles that we are taught to counter, I suspect that the samurai (all else being equal) would be able to adapt rapidly to a style or technique that they have never seen before. Secondly, a weapon like a rapier is fast, rapid and deadly. But against an expert of another style, I would expect any initially inflicted wounds to not be debilitating. Just about any contact with a katana and human flesh results in a major, debilitating wound, just from the very nature of the instrument and the techniques that are used. So I would suspect that a Renaissance expert would have to have several hits before debilitating the samurai, whereas the samurai would have to get only one, or at most two. I’m not saying that a Renaissance expert would not recognize the danger, but only that the samurai would have to get in one or two cuts, and not even full, proper cuts, to cause significant damage.
> but in MMA it’s not necessarily the most single-minded fighter > who wins but the one whose chosen martial art has more
> answers
I’m not sure what you mean about “most single-minded”. I would say that a trained samurai would be trained to know how to defend themselves against a very wide range of attacks from a wide range of different weapons using a katana. So contrary to some of the things one might read on the inter-tubes, a well trained samurai had techniques at their command that are very flexible and adaptable. For example, I’ve seen some people claim that the katana was not used for thrusting. This is wrong. They are not optimally designed for thrusting, but thrusts and counters to thrusts are a core part of the kata of all ryu that I am aware of.
January 16, 2014 at 5:44 pm
What I meant by single-mindedness is that the Renaissance swordsman, being a Renaissance man, probably does not spend as much time practicing technique as a samurai; but if his weapon/technique combi is superior to that of a samurai then he’ll win more often than not, rather as the striking-plus-grappling-skills unarmed martial arts win against the striking-only techniques once the practitioner of the former gets in close and takes the fight to ground.
I’m a believer in demystifying the martial arts, and after 10 years of it I’d summarise it as follows. Unarmed combat is based on the fact that there are only a finite number of effective moves, and for each way you can be attacked you practice repeatedly the responses to each (defence based on blocks and movement, feeding into attacking countermoves). What counts is not strength but awareness, speed, knowledge ingrained by practice, and determination. It is no more or less mystical than any other physical activity in which the stakes are high, and the amount of mysticism is merely a matter of cultural taste.
So if the samurai has not practiced vs Western-style swords, I don’t know who’d win or why. I’m glad of your comments but I didn’t see a “killer argument” and I think that we can’t really know, and we are unlikely to find out by experiment.
Advice I got for unarmed combat vs a sword was simple: unless you are about 6th Dan, run.
January 16, 2014 at 8:46 pm
Hi Anton,
Thanks for your thoughts, though I’m a bit confused and not sure what you’re saying. If you’re saying that someone with a greater level of expertise in their art is likely to defeat someone from a different art and who has a lower level of expertise, then I would agree (in general, though the more expert fighter might still make a blunder from being overconfident, but one could argue that in itself shows a lack of expertise). But the original question assumed that both were of equal expertise — at least that’s how I took it.
The analogy for between the “striking and grappling” vs “sticking only” only works if the person of the latter expertise allows the other to get into close quarters where they can apply their techniques. I’ve witnessed such contests and they are rather humiliating for one party that erroneously thinks they have the upper edge.
As for the demystifying of martial arts, I agree in general, but don’t think it’s a big problem. Maybe I’ve been fortunate in those that have taught me, but none of them have waxed mystical. Most of them actually explain things in terms of basic biomechanics, physics and psychology. Maybe I’ve been fortunate in that many of my teachers have been academics and maybe this mystical element is pervasive outside of those circles, I don’t know.
January 16, 2014 at 10:37 pm
Apologies Adrian, I’ve realised that I was using the word “technique” ambiguously. Usage 1 is that “technique” means jujitsu or karate or kung fu, etc, which I should have called ‘form’, and usage 2 means how good a guy is at his chosen form. I was using usage 1.
January 15, 2014 at 5:08 pm
is it that if you are wearing the sword it is not luggage?
January 15, 2014 at 11:39 pm
No, it is not luggage if you are wearing it…