Yesterday there was a conversation about scale, 'how big is 20 um'.
This reminded me of my early career where I used electronics manufacturing tools to create very small circuits. What is very small? No matter how small, there is always smaller, and no matter how large, there is always larger!
I measured these circuits at very cold temperatures by immersing them in liquid helium (this is when I learnt solder coax and triax connectors! Liquid helium 4.2 Kelvin (4.2 degrees C above absolute zero.
The aim of the circuits and measurements was to get control of those pesky electrons and show that they could be moved through a circuit 'one by one'. Before being at University I spent several years working on a sheep farm in Australia. Different scale and temperature, and different tools, but I learnt to move sheep around one by one so basically the same :) Change an environment and the things in it change as you might desire. In Taoism its called 'allowing without commanding'.
Anyway, this prompted me to share an image of the circuit that had wires as thin around 30 nano meters.
What I figured out how to do was create 'single electron transistors' by just making things very small and very cold. Of course like most science I did stand on the shoulders of those before me and 'carried the candle' to the next stage. When size changes occasionally the physics does too.
The alchemists say 'As above, so below'.