There’s no space for the extra space. By Farhad Manjoo on Slate.
I saw this piece earlier in the day and loved it. We don't need two spaces after the period. It's just a convention that can be changed. Although, as I typed this I found myself double-tapping the space bar after periods and corrected it after the fact. Ugh.
Also, why do people put their hats on AFTER they get outside? You lose all that heat off the top of your head and then trap cold air inside. Put it on before you get out the door and you won't even feel the transition into cold weather.