To begin our discussion of protective technologies, notionally, there are four types of shielding:
- particle shielding;
- ray shielding;
- gravity shielding;
- irreality shielding.
Particle & Ray Shielding
The most important and most common of these, of course, are the first two: particle shielding and ray shielding. Naturally, both of these are complete misnomers, thanks to wave/particle equivalence, and have an inconvenient degree of overlap, and yet they are the accepted engineering terms.
The technical definition of particle shielding is that it is intended to affect fermions, the particles which chiefly constitute matter, including quarks, the composite particles made up of them, and leptons; while ray shielding is intended to affect gauge bosons, such as the photon, gluon, and the various asthenons.
Thus, in the informal engineering view, particle shielding begins with conventional armor, Whipple shields, laser point-defense grids, and the like, while ray shielding can be considered to include such simple devices as high-reflectivity surfaces, HICAP and other high-Z materials, and even thermal dissipation systems or sheer mass. (Drunkwalking, of course, can be considered both.)
Later developments in particle shielding included a variety of technologies including sacrificial defense drones, semi-ablative fluff, fluid-foam armor, droplet nanoclouds, and gravimetric bubbles, the forerunners of the modern kinetic barriers.
Meanwhile, the story of attempts to advance ray shielding is a complex mess of dismissed technologies, ranging from entirely failed attempts such as FAT NINJA through variations on many others: magnetic plasma bubbles, dazzle nanoclouds, EM blisters, Meng mirrors, wormhole mouth-drones, antithetikon emitters, polariton photon-walls, stasis hyperspheres, claudications, and other metric warps, none of them achieving nearly the same success or general applicability as their particle counterparts.
All of which is to mostly ignore the inevitable overlap between technologies (for example: while often classified as “rays”, kinetic barriers are effective against particle beams; and attempts at producing kinetic barriers strong enough to deflect photons, which after all do have mass, continue – thereby classifying them as ray shielding, too), not to mention such bizarre entries in the field as the uncertainty sheath, singularity-lock armor, the blink displacer, UNMOVED MONAD, and its weaker cousin, the probability unseller.
Gravity Shielding
Intended to protect you from gravity and weapons that function on gravitic principles. Entirely hypothetical, unless you count “get your own equal and opposite gravity”.
Irreality Shielding
Intended to protect you from having the laws of physics you’re using edited out from under you, which also conveniently protects you from hypothetical dangers like extrauniversal invasions that bring their own physics along with them, falling through nilgularities, or outbreaks of primordial chaos within the brane. Currently consists of a single technology, the selective ontology evocation system, programmed with its most boring use, ensuring that everything stays exactly as it is.
– introduction to “Shielding” chapter, Celestime Technology Review
So, what’s the operating principles behind the Leviathan class dreadnought’s ray shielding?
I have some questions about some of the more exotic methods of shielding. What exactly are Meng mirror, antithetikons, and probability unsellers? The other unknowns mostly have relatively descriptive names, HICAP is probably some armor compound, and the uncertainty sheath is presumably inspired by the probability sheath you get when your research probability mechanics in Alpha Centauri.
No clue on Meng mirror, but since OGH has coined asthenon as a generic term for weak nuclear force gauge boson (a fantastic word I would nominate for the OED), I’m thinking antithetikon must mean one of two things:
As for probability unseller, I’m guessing that’s the reverse of a probability kiln. A p-kiln makes the improbable likely; a p-unseller would make something probable unlikely — delivering a No Sell to the attack, as it were.
Meng mirrors
The Meng mirror (named after its inventor) is essentially a perfect mirror - based on horrible, horrible metric manipulations - for photons and other bosons. At least until its capacity is exceeded and it undergoes catastrophic collapse; or what in modern systems, which prefer to project their mirrors as interlocked “scales”, is called a “burn-through”.
They have no effect at all on other particle classes apart from minor interference with boson interactions in the course of passage; i.e., kinetics sail right through 'em.
Originally invented both for shielding torch drives, and because gamma-ray mirrors are very, very useful in improving drive efficiency.
Antithetikon emitters
Not antimatter (these are strict ray shields, and don’t affect fermions), but they are anti-energy, in a sense; the notion is to project a wavicle such that the the attack and defense interfere and sum to zero everywhere where it matters (and hopefully only positively interfere in places where it won’t).
This was never a terribly practical technology (needs FTL sensors to work well without letting yourself be hit in the first place before reacting to it, outside purely experimental rigs; requires bizarre ship designs to fit around interference patterns; effectively turns shields into anti-weapons with many of the restrictions of weapons; etc., etc.) in the first place and while it was developed to the point of functionality, it never really made it out of the experimental classes, except in the subfield of gravity shielding (see “get your equal and opposite gravity”). Even there, it’s terrible, and survives primarily because there is literally no other option.
Probability unseller
@doctorcatfish nails this one.
(P.S. HICAP isn’t an armor compound, strictly speaking - it’s the waxy neutron absorber that’s mostly used for shielding reactors and torch drives so they don’t fry the squishies. But a good thick layer of it crammed into your armor just in case the oppo are using particle-beam weapons doesn’t hurt anything, especially since its physical characteristics let you cram it in between layers of Whipple shielding.)
While I hadn’t nailed it down strictly at the time, in that era, probably a scale array of Meng mirrors.