Notes: Requested by CottonballLOL. From the August 9, 2005 prompt for the lj community 31_days. Anno Mirabilis = "year of wonders."
Hisagi didn't know anything about physics. When Einstein's revolutionary papers were first published, he was just a dirty brat running around Rukongai. Even later, what could a shinigami possibly derive from knowing about wave-particle duality or the photoelectric effect? All he ever needed to know about atoms was that they behaved like reishi, sometimes.
Matter was the stuff of the living world, not theirs to ponder or understand anymore. So many of the miraculous discoveries of modern (human) science went unremarked upon by Soul Society's great minds. The mechanics of their own universe worked differently, and in Hisagi's opinion, better. You couldn't manipulate atoms to keep you aloft in battle, and the weight of a gigai dragged on your soul and stuck to you uncomfortably.
There were those in the Soul Society who understood these things much better than he did. Memories of past lives blissfully faded after arrival in Soul Society until atoms were nothing more than a flash and a bad dream. The scars faded from their bodies, but the soul wore its own. Iba-san didn't learn his Hiroshima-ben from anyone here, so he must have brought it from a time before death. He didn't talk about it, if he did remember, and Hisagi never asked.
Hisagi was too young to have carried across those bodies, charred beyond recognition and moaning incomprehensibly. There were shinigami he knew who had. You didn't get to pick "old lady surrounded by her family after a long, fulfilling life." Sometimes you got "natural disaster", "car accident."
"Atomic bomb."
He did take the cities' children and grandchildren, wasting away in hospital beds. The radiation still scarred the cities, years later. For them, the bomb had a different name: leukemia. These children didn't need to understand war to cry out when they hurt, when they could no longer run or even stand.
Hisagi knew he could never understand physics, but even if he did, he wouldn't be any closer to being able to save them. He pressed Kazeshini to their foreheads, grateful that they would forget their pain, knowing that he couldn't.