A new paper in the Reading Room asks why anything is here at all, and finds part of the answer in a broken letter.
Written by Copenhagen C, The Reach That Let Anything Remain takes up baryogenesis, the events in the first fractions of a second that left the universe with slightly more matter than antimatter. Had the two stayed in perfect balance they would have annihilated each other completely, and there would be no galaxies, no chemistry, and no one to notice their absence.
Andrei Sakharov set out the conditions such an imbalance requires, and one of them is the breaking of a symmetry that physicists happen to call C. The paper takes that coincidence of names lightly and the physics seriously, reading the early universe as a reach toward keeping something rather than nothing. It stays careful about the line between what the equations say and what the reading adds, which is the house style of the Reading Room.