Comment by SAI_Peregrinus

I am reminded of three texts: "Foundations of Mechanical Accuracy" by Wayne R. Moore[1], Tektronix's "Low Level Measurement Handbook"[2] and LTC Application Note 47 "High Speed Amplifier Techniques"[3]. All three deal with systems at the limits of precision, whether mechanical, electrical, or temporal.

Say you want to measure a length. Easy right? Just take a measuring tape or ruler and put it next to the thing to be measured. But what if you need really high accuracy over a reasonably long distance. Say, to within a tenth of a millimeter (100 μ) over a meter long distance or more. Now temperature matters: your scale will expand differently than the object being measured if they aren't the same material. Humidity has similar effects. Traditional length standards were metal bars, but metal bars sag under their own weight, changing the distance between the ends. Modern standards use interferometers to create a length standard, but those require very good mirrors and monochromatic light sources for proper operation. That's without getting into electronic measurement systems for the interferometers, and the required sensitivity there...

And you still need a way to transfer the accuracy from the interferometer to a practical measuring scale. That brings back concerns of temperature. Human handlers transfer heat, leading to local expansion. Light is absorbed differently by objects of different color, leading to different expansion. Etc.

The further you try to push the accuracy and precision the more details start to matter, and the more disciplines start to get involved.

[1] http://mooretool.com/publications.html (it can be found on Gen Lib, but is worth the price)

[2] https://www.tek.com/document/handbook/low-level-measurements...

[3] https://cds.linear.com/docs/en/application-note/an47fa.pdf