Before the subway doors open we New Yorkers do a dance of anticipation. It’s almost like holding our breath until the doors open, then letting our breath out in a rush as we move forward. Do I hesitate to see if anyone wants to exit first? Do I push forward without thinking and then have to self-correct when anxious travelers push out towards their destinations? The tension is higher when there are a lot of people waiting on the platform. It’s fascinating to watch and stressful to participate.