Luke F. Gale
A good, service, or right can be fungible.
Fungibility appears to be part of the structure of the universe. A gold atom is substitutable with any other gold atom. A methane molecule with another and so on. A carbon – hydrogen bond (C-H) is also fungible with another. In the early days of gold coins it was difficult to assay the purity of coins and debasing (reducing gold content) the coins was common. Now it’s trivial to assay a piece of gold using hand held laser scanners and digital scales. Similarly a cargeo of LNG can be examined to accurately determine if it is off specification. We are now in an era where the actual fungible units (eg gold atoms) can be traded because the cost of accurately quantifying the whole number of units (to within a very small error) is at or near zero. Because LNG cargeos are not pure methane its more practical to have mmBtu (a unit of energy) as the fungible unit. A shipping container is a fungible unit. Also a page of A4 paper. A bottle of water at the supermarket. For the biological world the units are amino acids.