Semi-Realistic Lightsaber Technology?

[Mishihari Lord]

As usual, walk away from the problem for a day or so and an answer becomes obvious - this just popped into my head while I was doing something else. Parallel wires with currents moving in opposite directions repel each other electromagnetically. Use monomolecular superconducting wire with a single molecule layer thick coating of carbon as an insulator. Arrange three loops like an egg whisker so that the six individual lines alternate in current direction. Add cross strands to keep the them in a long line rather than flying apart. Apply a large current and the whole thing becomes stiff. Turn it off or down and you can wind the thing up on a diamond spool.

So it cuts and can be retracted. No light or heat.

 

[Mishihari Lord]

I'm not sure you have. The issue here is torque (Force applied * distance from fulcrum). Electric charges repel each other, sure, so they apply a force, but they pretty much apply it *at* the fulcrum - they have a distance near zero. Meanwhile, gravity, and any force from contact with an object, has a fulcrum about the length of the blade to work with. Think of the old image of hair rising when someone touches a Van de Graf generator. Sure, it stands up, but it isn't *stiff*. It is floating, but loose and flexible, not rigid.

Easy fix: an insulated ring around the hilt with a very high static charge will keep the whole things stiff.

Thinking about it - the charges leave the blade at something approaching a notable fraction of the speed of light. Far faster than the blade is moving. So, you never get a cut from rigidity - the blade goes limp-noodle the *instant* it touches anything. The thing is not good for cutting - it is only good for applying an electrical shock at a reach of the length of the blade.

This one I consider up in the air. Once the strand loses rigidity it has very little momentum because of its mass. But there is also very little resistance to its cut because it's so sharp. I don't have a good feel for how much resistance there is, so it's tough to tell which one wins. SF portrays it a near zero, but the otherwise negligible resistance becomes important at this point.

I like the loop solution above better anyway.

 

[Umbran]

I like the loop solution above better anyway.

Yes. You realize that it is basically one application of the magnetic field solution I gave early on? Walk away from the problem, and we recognize the solution that was already given!

Mind you, it isn't that simple. A pair of wires will repel, but with six - each wire will be repelled from three, but attracted to two! You wind up with competing repulsion and attractions that will weaken the overall effect.

And I don't think "conducting core with insulation" gets to be a "mono-molecular wire". And we have six of them, not one. Much more resistance.

 

[Mishihari Lord]

Yes. You realize that it is basically one application of the magnetic field solution I gave early on? Walk away from the problem, and we recognize the solution that was already given!

Mind you, it isn't that simple. A pair of wires will repel, but with six - each wire will be repelled from three, but attracted to two! You wind up with competing repulsion and attractions that will weaken the overall effect.

And I don't think "conducting core with insulation" gets to be a "mono-molecular wire". And we have six of them, not one. Much more resistance.

No, I was thinking you were talking about magnetic fields projected from the hilt. The idea came from a toy problem from my fields class, a very long time ago.

Already checked the math on attracting and repelling wires, it works. Only took a few seconds.

A single layer of carbon bonded to the conductor will add very little to the width, and 6 times really small is still really small.

Anyway it's a plausible solution and we're down to quibbles, so I think we're done with this unless you have an idea of your own to propose.

 

[Umbran]

No, I was thinking you were talking about magnetic fields projected from the hilt.

Your misapprehension is not my problem

 

[Samloyal23]

Hmm... Is there any way to make a monofilament have the rigidity needed to parry with?

 

[MarkB]

Hmm... Is there any way to make a monofilament have the rigidity needed to parry with?

Even if you could, the only thing it'd parry is another monofilament. Anything else, it'd just cut through.

 

[Samloyal23]

Even if you could, the only thing it'd parry is another monofilament. Anything else, it'd just cut through.

That would make it worth fencing with, otherwise it is essentially a whip.