The Science of an Unbreakable Weapon.

[Blood Legend]

So here's something that's rolling around in my head. You have a sword, or a lance, something enchanted to be completely unbreakable, it wont even bend. All of the force that would go into it on one end passes through it. It absorbs nothing.

What does the user feel when he parries with this thing? Can he wield it at all? Can we exert forces on it to move it? Or is a perfect kinetic transmitter weird in real space?

If you use it as a lever, does the unbreakability do anything weird to how much weight you can knock around?

[whswhs]

Consider the case where your unbreakable weapon is 1.9 million miles long. (And really, really thin!) You hold one end. You poke the other end upward, and it bumps into a small asteroid that's passing by. The far end can't move, and since the weapon is completely rigid, the near end can't move, either. So you "feel" the solid object out there in space. But that means the force of the collision is transmitted to you in zero time. The asteroid is slightly over ten light-seconds away, so the force reached you faster than light.

Are you prepared to throw out special relativity?

[Ulzgoroth]

Absolute rigidity is weird, but there's no reason it has to translate to an immovable object. (It does, on the other hand, probably have to not be made up of atoms.)

Absolute force transmission, on the other hand, is nonsense. I mean, it really doesn't make any sense, that's just not how force works. Taken literally the object would be immovable because any force on it 'passes through', meaning that the object exerts an identical force somehow, on something. The reaction force on the object from it exerting that force would exactly counter the initial force, preventing the object from moving at all.

I'm going to ignore the 'absolute force transmission' thing. Give it a non-zero mass and let it move like an object with mass and relate to forces accordingly.

Typical elementary physics exercises treat everything (except occasional designated springs) as totally rigid and unbreakable and often massless. Levers don't gain any notably bizarre properties as a result.

The biomechanics of weapons probably make them unpleasant at best to wield, since there's no give in it to dampen the shock of any collision. An unbending lance might be particularly disastrous, but an unbending sword is probably rather bad.

Note that you could have an unbreakable weapon without it being unbending. All the weirdness comes from the unbending bit, not the unbreaking bit that you put in the title.

[whswhs]

All of Ulzgoroth's points look sound to me at first glance. I had thought of getting around to them, but I wanted to clear up the total rigidity issue first, so I haven't thought any of them through yet.

[Varyon]

Even if you make the weapon have absolute rigidity, the housing - the hilt, for example - doesn't have to, which may make it more comfortable to wield. Absolute force transmission means, as already mentioned, the object is completely immovable, and any pressure on it moves matter at the other end, which could generate some interesting air movement but makes the item nearly useless.

FWIW, the unbreakable wonder material I intend to use in one of my settings, Adamant Steel, does have some weird force transmission aspects, but that's just because I didn't want it to turn all damage in Crushing - a spear to the abdomen does greatly reduced damage when the target is wearing a corselet made of the stuff, and any sort of special after-wounding effect (poison, barbs, infected material, etc) is eliminated, but the target clearly suffers a stab wound. I've decided from this that Adamant Steel probably has some very interesting acoustic effects when making bells or similar out of it, but I have no idea what such effects would actually be.

[mr beer]

Yeah I'd go with 'bend, doesn't break' myself.

The other thing about unbreakable weapons is that they are usually unbreakable under normal conditions. I'd consider them somewhat like artifacts from D&D in that respect.

But divine beings or a unique method of breakage (Mount Doom etc.) may circumvent that. Cosmic damage might circumvent their immunity.

Hell being put in a no-mana zone and whaled on with sledgehammers could break unbreakable items that got that way via enchantment for example.

Arguably this might work with unbreakable materials that have a magical component like dragonbone - lots of GMs rule that large firebreathing intelligent dragons only grow that way in the presence of mana, so no mana may mean that the bone is now just very strong instead of unbreakable. Maybe that's how craftsmen carve dragonbone into staffs in the first place.

I'm not sure I'd ever have a completely non-breakable item. Even the weapons of the gods can be broken or destroyed in one way or another.

[AlexanderHowl]

I go with 'unbreakable under normal circumstances' myself. Anyway, anything truly unbreakable can be thrown into the Sun by a determine enough deity, mage, super, etc.

[Flyndaran]

The One Ring could be called, unbreakable, even if the entire story involved taking it to where it could be destroyed.

[Jack Sawyer]

I'd say 'unbreakable' would be best used conditionally. Like relative to the setting's technology and other assumptions. What is 'unbreakable' to a stone age or medieval society may not be breakable to a modern (or space age) society. It's sort of like one of those internet situations where a modern/advanced society could destroy the One Ring or if it was metaphysical - it depends.

The way OP uses it reminds me too much of Lensman inertialess drives and I get this impression you would not only have trouble holding it, but it would have trouble doing anything to any target (it sounds like it would be unable to 'collide' with anything, which is really how weapons would do damage...)

Instead, perhaps it is'unbreakable' because the magical enchantment is some sort of force field that adds structural strength to it. Think of the Star Trek 'structural integrity fields' or a Larry Niven General Products hull (I think those are forcefield enhanced?) The 'limits' of this field are so high that it is effectively resistant to damage from being dropped from great heights, stepped on by giant creatures, stuff like that (it may or may not 'adjust' said magical field to match new threats.) It probably would have limits, but those limits would be so high as to be effectively unbeatable.

Such a weapon would be impossible to deform or shatter or break up on impact, and would resist superhuman efforts to swing it. (If this effect were applied to a hypersonic bullet, it would behave as a perfectly rigid penetrator against an eroding target, rather than the 'both penetrator and target erode' that normally happens IRL.)

[malloyd]

Originally Posted by Jack Sawyer

The way OP uses it reminds me too much of Lensman inertialess drives and I get this impression you would not only have trouble holding it, but it would have trouble doing anything to any target (it sounds like it would be unable to 'collide' with anything, which is really how weapons would do damage...)

Yeah, there is something seriously wrong with that description. Can you even touch it? If forces go right through it, well, the thing that makes the surface solid is the reaction force to your contact with it. If the other side it transmitting your touch through to is open to air, then doesn't your hand go right through the object just like it would the air on the other side?

It does seem like it has a case of the same sort of nonsensical behavior as the inertialessness, in that the definition provided fails to imply the behavior you really wanted if you think about it a little harder.