I have taken the title of this post from Hesiod's book. Although I won’t talk about works here, I will talk about days. The word day has two different meanings: the whole day (24 hours) and the part of the day when there is sunlight. Thus, it could be said that
day =
day + night
which seems absurd, for a mathematician
could deduce that the night does not exist. Instead of that equation, and to
make it clear that there are two kinds of days, we should use this expression:
day1
= day2 + night
Here, day1 is a natural cycle, the period of the Earth's rotational motion around its axis. But then a problem arises: when can we say that the Earth has made one complete rotation around its axis? The problem is, to define the period of a moving object, it is necessary to have a reference point. The results will be different depending on which point is chosen.
