Scales aren’t changing and the weather won’t be noticeably different, but on May 20 the definitions that underlie what your scale and thermometer report—along with standard definitions used in chemistry and electronics—are undergoing a major overhaul. That’s the date that a more-than-centuries-long process of standardizing measurements reaches its conclusion.
Click here for original story, All base units of measurement now tied to defined constants rather than physical objects
Source: Phys.org