All base units of measurement now tied to defined constants rather than physical objects

This graphic appears today, May 21, 2019, on the main page of NIST (National Institute of Standards and Technology):
..
NIST is making available multimedia resources regarding the International System of Units (SI) makeover, at this link:https://www.nist.gov/si-redefinition/resources-reporters
.
NIST also posted this article:The ‘Gang of Five’ and the SI Revolution, by: Peter Mohr, May 20, 2019, at this link:https://www.nist.gov/blogs/taking-measure/gang-five-and-si-revolution
&mdash