In Vernor Vinges A Fire Upon the Deep (https://en.wikipedia.org/wiki/A_Fire_Upon_the_Deep#Time), the future human civilization uses [kilo|mega|giga]seconds as time units because nothing else makes sense in an environment where Earth is long gone and hibernating for years or decades between planetary visits is common.

(Beyond being great novels, the above and its prequel, A Deepness in the Sky, have points of interest to Unix and Usenet users.)