h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The most amount of times you can fold paper is 7 times, no matter how big or small the sheet you start with. I saw that once on "Why Don't You."
But anyway, cool entry on swords, they are great. My mate has some replicas, and they are bloody heavy to pick up, let alone swing about in battle.

A good sword shouldn't weigh more than 8 pounds... even the massive Claymores rarely topped this. They feel so much heavier because of leverage... the weight is so far away from your body, and is supported by your forearm, which isn't the strongest of muscles.

Colonel Sellers, proud owner of a new medium-length b*****d sword.

Ahhh...the claymore..... I just ordered myself a replica and it should be here in two weeks.


what ever shall I do with it......?

I wouldn't mind terribly, having a claymore myself. It's just that everywhere I look, they're a bit too expensive in comparison with what my economy will allow.
Any tips on where one can find claymores and order them for a reasonable price? Preferrably in the UK.

Re: paper folding.
Some-one forgot the fact that we're dealing with metal,not paper. Metal,ie,Iron, is heated and beaten to make it thinner and more easily worked, in the forge it also picks up carbon making it steel. Therefore folding iron 2000 times is not impossible, as any blacksmith or metalurgist can attest. Origami has very little to do with the art of sword-smithing.

Rocket (ni-dan, ni to ichi ryu, also metal tradesman)

I've been told that folding iron or steel in half 2000 times IS impossible. It doesn't have the necessary... um... bendiness. (There's a scientific word for how far you can stretch, fold, and hammer metal, but it escapes me) Gold, on the other hand, is far more resilient, and CAN be folded in half many, many, many times. (Possibly not 2000, I don't know.)

I'm not very much into mettalurgy, so please correct me if I'm wrong:

As I understand it, the object of folding a piece of metal many and many times is to get multiple layers of material, which tend to be more flexible than a solid piece of material.

Steel mainly consists of iron, scietifically known as fe. The size of an atom of fe is 1,241 E^-10 meters, or 124,1 pm (picometers). That means to me that the thinnest layer you can (theoretically) achieve by folding and hammering a peace of iron has a thickness of ONE atom, i.e. 124,1 pm. If you fold the material 30 times, you will get 2^30 =1.073.741.824 layers of iron; 124,1 pm x 1.073.741.824 = 0,13325 m = app. 13 cm = 5 1/4 inches. That seems to be quite a decent thickness for a sword.

Just for fun: 1000 foldings result in a theoretical thickness of 1.3297 E^291 m. Compared to the size of the known Einstein Universe which is, without worrying about some exponentials, some 1 E^27 m, THAT'S beyond any imagination.

O.K picture this.First take a length of iron, approx 2"x1/4"x36"long.Place this in the forge(an air inducted charcoal fire). Wait until it is yellow-white hot,then beat it on an anvil with a hammer(4lb will do),the metal will become thinner and wider and a bit longer. Place it back in the fire and re-heat. Next using various tools of black-smithing fold this and hammer it flat. Re-heat and hammer, this will weld the two parts together. This procedure is repeated many many times. A skilled artisan can retain the desired shape through-out these steps. Everything depends on the type of metal and the type/temperature of the fire(also the patience of the smithy). Whilst I admire your mathematics, you must remember we are dealing with metal in a semi-molten state where it is at it's most malleable. For more info I would suggest a visit to a real black-smiths workshop, or the metallurgy dept.of your local T.A.F.E or Uni.

Hope this helps.
Rocket (been bashin' iron for 20 odd years an' it seems to work for me)

I don't know for sure, but I'll make the point anyway so that others (hopefully a little more knowledgable than myself) can answer.

If you repeatedly fold the semi-molten metal, do the molecular bonds not come under huge stresses? I believe that one effect of folding the metal is to stretch out the molecules, so that its as if a whole load of parallel molecules have been folded up. You certainly get this effect with blu-tac - folded enough times, even when warm and pliable, it gets to a point where it snaps rather than stretches. To get it back to its original state, you need to roll it up randomly, so the 'molecule chains' are not all stretched to their elastic limit.

I do understand than the repeated hammering an folding ist done with the steel being heated, almost melted, and I know that the layers are welded together.

But: When the steel has been folded about 30 times, the layers have reached their minimum thickness, so what is the benefit of folding it another 20, 200 or 2000 times?

Am I right in the suggestion that only the first 10, 20, 30 foldings are done to get layers ("sandwich material")?

And from that point the hammering only is done to get a more homogenous molecular structure within the steel, and the workpiece has to be folded to get it back in shape again?

Is there really a difference between 50 an 100 foldings?

Someone find a blacksmith!

I found the following site on the web:

http://www.ii.uib.nkjartan/swordfaq/

There they say that a japanese sword is folded (depending on the smith) about 10 times, resulting in 1000 layers of steel. Some smiths fold there swords up to 16 times (65000 layers). This makes me think that maybe we have confounded foldings with layers. Sorry if it was my mistake!

it isn't just the malleability but the ductility comes into play too - the folding isn't folding like paper but folding and drawing out and hammering together.

metals do not have molecules - they are just atoms linked together

blu tac will snap because of its nature

metals, at the right temperature, will fold and be hammered together much more, you just need a REALLY good swordsmith

oh and elastic limit isn't applicable here either, really, you're talking about plasticity effects

I'm not saying 2000 is possible, just that an awful lot of times are much more possible than people think.

This is totally off the point (get it? sword, point, oh never mind), but do any of you lot fancy a party? We're a bit short of blokes over at http://www.h2g2.com/F47171?thread=61929. I'm (supposedly) serving ice creams nearby. And there's some sort of smoking beer crate knocking about somewhere.

Ductility! That's the word I was trying to remember.

And yes, you can easily make a sword 2000 layers thick. That's where the misunderstanding sets in. But folding a sword 2000 times... and the number doubles every time... That has to be in the 7 figures.

If you fold something, every time you fold it the number of layers doubles. So one can easily figure out how many layers there are just by doing 2^number of folds. Keep in mind 2^10 = 1024, and 2^100 = 1,267,650,600,228,229,401,496,703,205,376.
Imagine 2^2000. Seven figures is a bit of an understatement.
I will give you the real number shortly, but I'm too tired to do the math at the moment, and my calculator bit me when I tried it there.

Btw, In mathematics we tend to refer to numbers like this as "really f*****g big" unless you represent them in a different way, which most people just squint at. 2^2000 = 1.148130695274254524232833201178e+602.

Why are bastard swords so called?

A bastard sword is not quite a long sword, not quite a broadsword. It also has the option of being used one-handed or two-handed... most two-handed swords, like claymores, were too heavy to use one handed, and most one-handed swords, like long swords, only had enough room on the grip for one hand.

So it has properties of pretty much everything, and the result is something not quite like anything else, like a mutt or a bastard.

Ahhh, I see.