system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can scientists create measuring tools more accurate than the tools we already have? Doesn't the accuracy of new tools depend on the accuracy of the tools used to make it?
gpt
There are methods for creating accurate without already having an accurate thing.

Like finding the mid-point between two points. Attach a pencil to a string and attach a string to a needle that you stick at point A. As long as the string is more than half the distance to the second point, you can can draw a large arc with it.

Then repeat the process from the other point. There will be two points at which the arcs intersect. If you draw a line between those points and draw another line between the two original points, you will have accurately determined the mid-point using "in-accurate" tools.