I received the following e-mail recently:
“Your origin of the word smithereens I believe is in error as is also the different one shown at Wickipedia. When I was taking physics at school in the 1930’s, I was taught that early in the nineteenth century a physicist by the name of Smith thought he had discovered the smallest possible particle, which he called the ‘smithereen’, which I think proved to be the molecule.”
Forgive the delay in responding; we have been unusually busy since the first of the year and just completed a difficult job that took us from the first of the year until last week to complete.
The first problem your theory faces is that for it to work, the physicist would have had to have been named “Smithers”. That would require but a minor change in your theory. However, the history of your explanation presents a greater problem.
In point of fact, molecules were being discussed by Descartes already in the seventeenth century, so the report that someone named Smith (or Smithers) discovered the smallest particle in the nineteenth century does not fit the historical facts. The word molecule was available in French since at least the early seventeenth century. The first published instance of the word in English traces back to 1674, according to the Oxford English Dictionary.
I’m afraid the story you picked up in your physics class is just another urban legend introduced by a dilettante etymologist in the past. The general rule to follow is this: if the etymology is obvious, it is probably an urban legend. Words change very rapidly over time and are seldom subject to simple analysis.