Shakespeare asked the question in “Romeo and Juliet.” You remember: that which we call a rose by any other name would smell as sweet.

So, names don’t matter?

They do if they live on as units.

Of course I’ve skipped ahead a few centuries, but I’ve always been fascinated by the names of units. In science, there are many that are named after key figures. We have the newton (unit of force); the ohm (unit of electrical resistance); watts (unit of power); the Tesla (yes, that one, unit of magnetic flux density); and dozens more here, including my favorite, the curie (radioactivity).

One that may also be familiar is the Mach, named after Ernst Mach whose work in aerodynamics led to the understanding of supersonic speeds. The Mach number is the ratio of the speed of an object to the speed of sound in the surrounding medium.

Why do I think of Mach today? Because this week marks the 75th anniversary of the breaking of the sound barrier. On October 14, 1947, pilot Chuck Yeager flew faster than Mach 1, the speed of sound. Details of the flight are here.

What’s your favorite unit?