I'm not sure if this question belongs on English SE, but the following question is about word origins.
Let's take two words: update and outdate.
Update means to make (something) more modern or up to date.
Outdate means to to make out of date : make obsolete.
So, we can say, more or less, that update and outdate are opposites or antonyms.
So, why are the prefixes up and out rather than up and down or in and out?
Wouldn't update/downdate or indate/outdate make more sense? Where did the origin of the prefixes up/out come from?