Well then, since you ask!
It's actually pretty simple, just let me explain something up front. The 'big lie' of the Fifth Secret is that negative gravity is possible; that's important, because--
In the real world, gravity is the worst possible weapon. It barely interacts with anything at all; if you try to use it as a weapon, you'll find your opponent is barely affected; the gravity waves -- I'm presuming you'd use gravity waves, not a static field -- will pass right through them, primarily affecting the rest of the universe. If you try to improve that by using more, you'll simply tear yourself apart.
There's one way to work around this. For any given field, if you put a positive charge in one spot and a negative charge somewhere close by, then there'll be a net field when you're close but no noticeable field when you're far away. Since it depends on distance, this is called "near-field" behavior. Since you're no longer affecting the entire universe, you don't need to pay the energy cost of doing so; only the cost of affecting whatever is close to your emitters.
This can be used, for example, to create reasonably efficient wireless phone chargers. Or, for the Fifth, a ruinous vortex of gravity that largely ignores the gravitational shielding used by our ships to stop every
other attack.
Negative gravity doesn't exist in real life, as far as we can tell. In the Practice War universe, it does. This possibility is also art of what enables the First.
= = =
There's a lot of ways you can make use of this sort of ability. What a particularly clever group of (simulated) Shiplord allies did was to fire a torpedo -- you'll understand why, momentarily -- which generated a powerful but radially symmetric gravitational field around itself, leaving the 'negative gravity' part of this outside the 'positive gravity' part. Really, very simple. It was however powerful enough to causally unlink the inside of the field from the outside.
In other words, they created an artificial black hole; one held together only by the artificial gravity of the torpedo's generators.
This in itself is just an interesting weapon. It immediately collapsed in on itself at the speed of light, crushing the torpedo into a central singularity, along with any Hijivn vessels unlucky enough to be nearby. Obviously this destroyed the machinery keeping the bubble stable, so it dissipated into--
Not so fast!
The gravitational field wasn't perfectly balanced. There was the negative and positive gravity fields generated by the Fifth, which were
vastly more powerful than the natural fields, but the natural fields still existed. The things doing this had mass. So, as those were crushed into a central singularity, after all was said and done we ended up with a natural, ordinary, stable black hole weighing around... let's say, 1,000 tons just for the torpedo, plus however much the Hijivn ships, random space dust, and whatever else might be nearby weighed.
You could also detonate this on an asteroid, if the presence of enemy combatants is a problem. It won't have much bearing on what's about to happen.
A 1,000-ton black hole is really rather teensy, and has a proportionally tiny lifespan. It'll evaporate through Hawking radiation in the course of approximately 0.1 seconds, converting all of the mass it contains into high-energy gamma rays. As well as the occasional electron-positron pairs, which will immediately become high-energy gamma rays.
This amounts to around 1,000 gigatons of TNT, just for the torpedo. Add in however much whatever else is nearby weighs.
The limiting factor to this sort of weapon is that, if you give it too much food, you'll get an actually stable black hole instead of one in the final throes of disintegration. To cope with that, you might try to impose a negative gravity field on it externally, in order to make it evaporate faster; this wouldn't work though, because your generator will likely be destroyed before it has a chance to fully evaporate. The speed of evaporation scales with the strength of the negative gravity field, so if you make it powerful
enough you might be able to avoid that, but then you risk exceeding the field generated by the mass-energy of the hole, and--
Don't do that.
= = =
Somewhat amusingly, the best real-world black hole bomb we've thought up is actually
even more destructive. Less usable in direct warfare, but a potential galaxy-buster if built.
