Last Thursday Massachusetts Institute of Technology graduate student Seyoon Ragavan sent a new quantum cryptography proof to his friend Yao-Ting Lin, a doctoral student at the University of California, Santa Barbara. Lin could not look at it right away, though. He was in a meeting with his adviser, U.C.S.B. professor Prabhanjan Ananth, where he heard about another proof of the same result. After the meeting, he e-mailed back to Ragavan, “We are definitely living in strange times.”That day resear...