If you are dealing with physics, like a satellite course, "wall time clock" is irrelevant. Wall time clock is a human construct that is ambiguous in many edge c

If you are dealing with physics, like a satellite course, "wall time clock" is irrelevant. Wall time clock is a human construct that is ambiguous in many edge cases, dependent on position and local politics. Indeed, your son's friend's age is an ambiguous notion, Hence the need of a more precise contract than a simple date.