The 3-7 km region of the earth's surface is almost oxygen-free, air is thin (little oxygen gas; air molecules are too far apart), temperatures are around -20c to -15c . The gas that is predominant is nitrogen. Due to temperaature, the ability of living beings to exist at this distance is low, since the environment is unheard of.
While George takes the bus home, he is thinking about how to resolve a difficult issue at work. This is an example of the mind working to solve a problem.
