Today, October 21, is the day in history when Thomas Edison applied for a patent for his version of the electric light bulb. Which was, in many ways, the canonical invention. In fact, the light bulb is the most often used symbol for the idea of invention itself.
Today is also the day in history, in fact exactly 40 years ago, when a length of one meter was first officially defined as the distance that light travels through a vacuum in a precisely defined period of time.
I can’t help but feel that those two events are connected. Each of these bright ideas, in its way, illuminates the other.