The Chicago Manual of Style requires a single space after a period.
In the beginning, when monks transcribed their pages, the letters were proportional, or, of varying widths.
Then they invented the typewriter and the NON proportional courier font. Each letter took up the same amount of space, and the period took the same amount of space as a W. In order to make sentences look better, two spaces were added after the period.
About the same time as the typewriter was invented, typing teachers were invented and they taught us Period Space Space.
After awhile, proportional font was invented, and the period was also proportional — so there was no longer a need for the extra space. But the typing teachers were still there, teaching Period Space Space . . . much like the proverbial mother inadvertently teaching her son how to cook a roast.
You’ve heard the story?
When the mother cooked the roast, she cut off both ends, stuck the roast in the pan and placed the ends on either side of the roast. Her son learned that this was the way to cook a roast. Then he got married. He noticed his wife did not cut off the ends of the roast before cooking it. So he was confused, and one day, he finally asked his mother why she cut off the ends of the roast before cooking it.
At first the mother didn’t know what he was talking about. Then she remembered. It was because her roasting pan was too small. The only way to fit the roast was to cut off the ends.
Because typewriters started off with non proportional fonts, and we wanted to set off the spacing between sentences, that’s the way we had to do it. Now, with a proportional period, that extra space jumps off the page and looks disrupting.
No more Period Space Space.
Sorry, Ryan and Kyle, I was wrong. Please just use one space after a period. And cook your roast however you like.
photo from iStockphoto.com #000017126082