I was trying to see today if I could exercise more by just pacing thru my house. I was trying to figure out if maybe walking from room to room, in and out, then back again would be a long enough distance. IOW, what distance that would be. I think it's about 1/20th of a mile. You know it's interesting how I found this out. The English word for mile is from the ancient Roman "mīlle passus", or thousand paces. (A pace, to the ancient Romans, was two short steps. Who knows why. Or a yard. IOW, three feet.) I don't know the whole history why the English mile is 5,280 feet, and not 3,000 feet like the ancient Roman mile I just know they say that the English had the idea that a mile consisted of eight furlongs, or again 5,280 feet. But you know that's a quick and easy way to measure distances really quick. Just count two short paces. Each one should be about 3 feet.
Early in my career I spent a lot of time doing field forestry work. Much of that time was spent measuring distances by pacing and we got pretty good at it. For those applications where measuring with a surveyors chain was not necessary pacing was a perfectly acceptable means of distance measurement.
Inuit people drew maps and also measured distance and time, not in miles or minutes, but in “sleeps.” The number of sleeps made in a journey determined when he or she will get to their destination. The kos also spelled coss, koss, kosh, koh(in Punjabi), krosh, and krosha, is a unit of measurement which is derived from a sanskrit term, क्रोश krośa, which means a 'call', as the unit was supposed to represent the distance at which another human could be heard. It is an indian subcontinental standard unit of distance, in use since at least 4 BCE. According to the Arthashastra, a krośa or kos is about 3,000 metres (9,800 ft)
USA here feet and inches, know little about metric, and too old to learn. Laser measure is here and very accurate but still use old tape measure. Have stepped off yards before, and guess row spacing in my garden and rows are pretty accurate.
If you want to measure distance on a nanometer scale you can use scanning electron microscopy. Scanning electron microscopy is a highly versatile technique used to obtain high-resolution images and detailed surface information of samples. It is a type of electron microscopy that uses a focused beam of electrons to scan the surface of a specimen and generate images at a much greater resolution compared to optical microscopy. The resolution of SEM instruments can range from < 1 nanometer up to several nanometers. One nanometer is 6.1877(10^25) Planck lengths. You can't measure anything smaller than the planck length due to quantum uncertainty.
