system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Standards for measurement units (time, length, etc) have developed so that they become more accurate than the one made before. But how can people find out that their new standards is more accurate than the one before if that was the standard?
gpt
It isn't that they are more *accurate* but that they are more *precise* in the sense that they:

A) define a standard of measure to a greater degree of precision (more significant digits); and

B) are based more firmly in fundamental constants (such as the speed of light).