Yes, it bears repeating: Mikoto is the right kind of tsundere. :3
I'm also finding the Railgun manga more interesting than the Index manga so far. I expect that the Index novels are good (since they've continued on for so long) but my Japanese needs to level up before I can read novels at a decent pace.
In chapter 4 they go into more detail about the "Graviton" stuff. Since I like to compare sci-fi physics to real-world physics...
Spoiler for science-y rant:
In the standard model of particle physics, each force is carried by a different kind of particle. There are four fundamental forces, and they each have one or more associated force carrier particles: photons carry the electromagnetic force, W and Z bosons carry the weak nuclear force, and gluons carry the strong nuclear force. Since these models have been so successful for the above three forces, theorists have proposed the graviton as the hypothetical particle that carries the force of gravity. For various reasons (see
Wikipedia) we're not able to experimentally detect gravitons like we can other particles. Furthermore, there are theoretical problems with this approach.
But enough about real physics. On page 91 of volume one, Shirai-san says something like: "Using (a piece of) aluminum as a basis, the number of gravitons is increased at a precipitous rate. It (the aluminum) then suddenly disperses into the surrounding area". Referring to video games and such, the way a graviton bomb typically functions is by creating a black hole, which produces radiation when it consumes material or evaporates via
Hawking radiation. The WP article has some interesting numbers that suggest that a low-mass black hole could produce a pretty nasty explosion.
/me decides to read more Railgun