Sci-fi Weapons, Vehicles and Equipment

The idea that you expend energy to form a Casimir field however is a plain error of fact. You need energy - in the form of two plates - but that's not the same as expending anything.

The Casimir effect will try to pull the plates together. You need to expend energy to resist this force.

Nope. Applying a force consumes energy only if there is a resulting movement. And that is middle school level physics.

If there is a net force attracting the plates together, they will try to come together. Once they do, there is no longer any separation and thus no Casimir effect. To oppose this, a force must be exerted in the opposite direction. If the plates are held in tension, then the net force is zero and there is no energy, positive or negative.

So? It's not expending any more energy than the legs of a table.

And therefore there is no negative energy density, so no wormhole.

Energy density does not work that way. Exhibit A being black holes which exist even though averaged energy densities wouldn't allow them, because the Einstein field equations work with local energy density not global one. Besides, nothing about the discussions of Casimir wormholes support what you say.

I'm expressing myself poorly. Gravitational fields do not create a force; in fact something moving along with the natural curvature of spacetime is in an inertial reference frame. Any resistance to this curvature is a force. When you stand on the Earth's surface, you are not still. Technically, you are accelerating at 9.8 m/s against the natural curvature of spacetime. This force is real and creates pressure, which can be measured on a scale. A table whose legs rest on the floor is also experiencing a net force upwards.

In a black hole, curvature is so great that it overcomes the degeneracy pressure of matter and there is nothing left to stop it from falling inward to the singularity. Matter falling in this manner is inertial, unless it's experiencing radiation or magnetic pressure from surrounding matter.

What I'm not sure about with respect to the Casimir effect is whether it represents a force in the classical sense or if removal of the vacuum energy within that narrow space represents a gravity-based curvature of spacetime. If it is a classical force, then suggesting that there is negative energy density between the plates is no more sensible than saying there's negative energy density in a box that's had all the air removed. The box doesn't experience antigravity.

Just because that force is a quantum mechanical effect doesn't mean it ignores Newtonian laws, and holding the plates apart requires a counter-force that has a positive energy density.

Edited by Fighteer on May 5th 2021 at 3:17:19 PM

Okay so I'm stuck on the idea of sci-fi melee weapons.

Knives obviously, but I'm also thinking like axes, hammers, flails, not swords that's pretty obvious.

How would you build a functional melee weapon with future technology? Feel free to be creative.

Umm... it's very sharp? The physics of applying pressure are fairly well established. We might develop better materials that improve on the salient characteristics: strength, durability, edge sharpness, etc., but overall "stick that cuts things" is a timeless idea.

Edited by Fighteer on May 5th 2021 at 7:03:39 AM

Impact pneumatic devices. They use them to do things like drive home nails. Other works use something called the Pile Bunker, the same concept except the spike or impactor is typically driven by explosive force or a large caliber cartridge. Basically, it's kind of hard to go with something pointy. Chisel tip-like designs would be handy for cracking open say a helmet or prying apart protective layers.

Truly exotic, a projectile or spear-like weapon that has an electric tether or a power pack. You stick it in and it discharges frying the person and/or their suit.

Axes are always a good choice, they work well as a survival tool AND a weapon, and things that pull double duty are always nice.

Gundam is in love with melee weapons; granted, most of them are Laser Blade swords. One particular exception is the beam tonfa, which is basically the same as a beam saber, just forearm-mounted rather than handheld, allowing it to be fed directly off of the Humongous Mecha's reactor instead of being battery-powered.

CE copypastes the idea of the beam saber, but with the caveat that CE sabers are just regular plasma without any Minovsky Physics in play. As such, these sabers cannot Blade Lock; they'll just harmlessly phase through each other, so the only way to stop one is with a physical shield specially treated with plasma-resistant ablative coating.

PD is where things get interesting, because unlike other timelines where energy weapons tend to be instant-kill against anything without countermeasures against it, PD armor tech has leapfrogged weapon tech so much that energy weapons fell out of use completely because even the weakest Mook can shrug it off with only the optics, weapons and other exposed components suffering any visible damage at all (against civilian targets, on the other hand, it's horrifically effective). Thus, everyone uses kinetic weapons exclusively, although the only thing that can reliably penetrate battleship-grade armor at any range (railguns firing 15 meter long projectiles made of a superdense alloy) is classified as a WMD and banned by treaty due to its sheer destructive power when used for Orbital Bombardment. For conventional weapons, even 120mm cannons can't penetrate beyond a few hundred meters and swords are about as useful as against a medieval knight in full plate armor (ie. precision stab between two plates is the only thing that really works).

Hence why Mooks use axes and the main character's preferred melee weapon is a giant fuckoff mace with a telescopic handle and a pile driver in the tip, as it's pretty much the only thing with enough force behind it to reliably One-Hit Kill a mook on a cockpit hit.

Is there any truth to the whole blade sharped with lasers as proposed in Batman Beyond?

You're referring the Curaré episode where Bruce says the sword was "sharpened by lasers to and edge no thicker than a molecule." I don't know if (in the future) it would be possible for lasers to make the edge that narrow, but the thing is, if your edge is that fine, it won't be very durable.

On the topic of bladed future weapons, Vibroweapon is a trope that sees a fair bit of use. And yes, I know it's not particularly realistic.

Edited by WillKeaton on May 5th 2021 at 7:38:25 AM

Sharp is sharp. The thinner you make an edge, the better it cuts, but the more it deforms with impact. The deciding factor is the material, not the sharpening method.

Well if I'm building a utility/emergency backup weapon, I could use a plasma torch as a sort of knife. Think an arc welder but handheld. Cut through metals (or weld things shut), perform repairs or disabling on equipment and various other things.

Then there's always the Laser Blade.

Tuffel mentioned the Pile Bunker, basically a jackhammer head attached to a piston fired by cartridges, magnetic acceleration, pneumatic/hydraulic pressure, or other methods. Very high impact pressure but difficult to use.

I would also stipulate what I'd call a Nano-Tool. Basically a Nanomachines formed tool for use as a weapon or utility function. It could form itself into a knife or other cutting blade like a saw or machete, a hatchet, a prybar, a hammer, or a combination of the above.

In total, never underestimate the value of utility functions. Many traditional melee weapons of the last few centuries from knives to bayonets to maces and more all had or were developed with utility functions in mind too or were used as such. (The classic prodding the ground with your bayonets after Land Mine Goes "Click!" comes to mind.)

This whole discussion reminds me of a comic book back in the day where the character's axe was so "sharp" that it could cut through gravity.

Try not to think about it too hard.

> I don't know if (in the future) it would be possible for lasers to make the edge that narrow, but the thing is, if your edge is that fine, it won't be very durable.

In theory they could, but i think the heat from the lasers will just deform the edge. We tend to use electron beams for such fine cutting.

But yea, the issue with a molecule-thick blade is that you also have the strength of a molecule-thick blade. It would probably work very well exactly once, if you hit it right.

That might be good for say things that just need to cut tissue but anything truly hard might mess up the edge as it cut.

Anything would damage the edge. The softer it is, the slower this would go. Steel is many many many times harder than tissue yet you still have to sharpen your knives.

Cardboard is the bane of all sharp items

"How would you build a functional melee weapon with future technology?"

Well, son, you take your laser rifle and hit him over the head with the stock.

Making a "blade" out of plasma or lasers doesn't improve cutting power at all. It causes things to explode in flames when struck. If that's your goal, great, but at that point you're not really wielding a melee weapon but an unusually short-ranged energy weapon.

"But, Fighteer," you ask, "What about cutting through metal and stuff?" Have you seen a plasma or laser cutter going through metal? It's slow, for one thing. For another, the user has to wear thick protective equipment and a face shield to avoid being burned and blinded. An "elegant weapon" this is not. It's about as far from elegant as it's possible to get unless your high-class parties feature goresplosions and third-degree flash burns.

As for electrifying a blade so you can zap people when you cut or stab them? Sure, I guess. I'm not sure how you'd form a circuit, though. A Taser has two prongs that conduct current through the target. You can't really get a positive and negative pole when you're wielding a solid metal blade. You could deliver a static shock, but it's very hard to control those.

Every bladed weapon in existence is based on one of the simplest tools: the wedge. Pressure is force divided by area, so the smaller the area of contact, the higher the pressure, and thus the higher the cutting power. The most effective cutting tool therefore has the sharpest possible edge/point, and to be effective more than once, it must be durable enough to survive multiple uses. Putting extra crap on the blade to burn or shock things is missing the point. Literally.

Being heavier and moving faster are also advantages (force = mass x velocity), so anything that can improve those is also an advantage. Generally, a heavier weapon is harder to swing, so giving the wielder a mechanical advantage, such as by using robotics or, I don't know, rockets, will increase the weight that can be effectively wielded, increasing damage.

So, how can we improve melee weapons? Make them from better materials and give the wielder mechanical advantages.

Edit: I had a thought about the shock idea: a spiked mace could use a non-conductive material for the ball and have the spikes close the circuit. That way you can get crushing, piercing, and zapping all in one package.

Edited by Fighteer on May 6th 2021 at 9:28:46 AM

You can do it with a sword too, provided the conducting elements are insulated, except at the exposed tips. Why you would want to do this is a different issue.