The trouble with time started a century ago, when Einstein’s special and general theories of relativity demolished the idea of time as a universal constant. One consequence is that the past, present, and future are not absolutes. Einstein’s theories also opened a rift in physics because the rules of general relativity (which describe gravity and the large-scale structure of the cosmos) seem incompatible with those of quantum physics (which govern the realm of the tiny).
"Great! I'll use this one on the boss next time I'm late!"