It would be silly to to measure the number of inches in a foot. An inch was DEFINED to be 1/12 of a foot by King John, or by some committee somewhere. The number 12 is just a conversion factor from feet to inches. Feet and inches are just two arbitrary units for the same thing, distance in space. So Sam Serious is not to be taken seriously.

So what about measuring the speed of light? Fifty or one hundred years ago people made measurements of the speed of light. No longer! Here is the speed of light:

c = 299792458 Meter/Second

The number 299792458 is exact because it was DEFINED by a committee. It is just a conversion factor from seconds to meters. Seconds and meters are just two arbitrary units for the same thing, an interval in SPACETIME. In fact, in modern physics it is easy to remember the speed of light. It is just 1. That is 1 with no units added. Then multiplying through by seconds we see what 1 second is in terms of meters.

c = 1 = 299792458 Meter/Second

or 1 Second = 299792458 Meter

This is no different than converting between feet and inches. So Susan is not so serendipitous! Want to SEE a nanosecond? Just cut a piece of wire 11.8 inches long - that's a nanosecond, the distance light travels in 1 nanosecond.