The current goal is to redefine the second in terms of an optical frequency once clocks are available that offer a higher precision than 1 second over the lifet

The current goal is to redefine the second in terms of an optical frequency once clocks are available that offer a higher precision than 1 second over the lifetime of the universe. https://www.nist.gov/si-redefinition/second-future https://www.nist.gov/si-redefinition/second-future