National Maximum Speed Law for the 55 mph speed limit offered, "Speed limit 55. It's not just a good idea. It's the law.". Intelligentsia riffed that with a more absolute statement based on the speed of light: "186,000 miles per second. It's not just a good idea, it's the law." National Maximum Speed Law The National Maximum Speed Law (NMSL) in the United States was a provision of the Federal 1974 Emergency Highway Energy Conservation Act that prohibited speed limits higher than . It was drafted in response to oil price spikes and supply disruptions during the 1973 oil crisis. While Federal officials hoped
Light-second presently defined to be equal to precisely light-seconds, since the definition of a year is based on a Julian year (not Gregorian year) of exactly 365.25 days, each of exactly SI seconds. Communications signals on Earth rarely travel at precisely the speed of light in free space. Distances in fractions of a light-second are useful for planning telecommunications networks. The light-second is a convenient unit for measuring distances in the inner Solar System, since it corresponds very closely to the radiometric data used to determine them. (The match is not exact for an Earth-based observer because of a very small