Both ideas/concepts center on somewhat unanswerable questions and which relate to much of the human experience. The first one is about simultaneity.
How many people at this exact instant in time are doing exactly what you're doing? Or, How many people at this exact instant in time around the world are doing ____ (fill in the blank with whatever you want)?
I'm sure this is a common thought that most people think about at one point or another. I've only seen in it in pop culture in the movie Amélie, in the scene where multiple people around the world are shown to be doing the same "activity."
I often think about this when I'm alone or when I'm doing something that is usually very mundane, like taking out the trash. How many people are drudging through this with me? However, the thought also comes to me when I'm doing something special, like blowing out birthday candles. It is often in such special, fleeting moments that I like to realize that with the vastness of humanity (and the similarity between people) that someone else must be doing exactly what I'm doing.
This realization makes me feel less alone and somehow connected to others that I can't see or know. Maybe someone can do an analysis of how many Twitter posts happen each instant that are about people doing the same activity. I know there are many trending Twitter topics that are popular to write and think about, and I'm less interested in how many people are thinking about the same thing than how many people are doing the same thing.
Maybe someone else out there is blogging about simultaneity as we speak. Hopefully they subscribe to my feed.