Yesterday I came across some grammatical rules which said “に is used to
indicate a specific time or date, but in the case of a relative date, に is not
used. I know relative time include terms like yesterday, tomorrow, and today.
But can someone give me a more accurate definition of relative date? Thank
you~
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2019-05-28T21:57:19.527
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2019-05-29T21:06:55.297
2019-05-29T07:24:37.210
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question
grammar particle-に time relative-tense
what is relative time in Japanese language?
Absolute times are ones that stay where they are as time moves onwards, or to
think of it another way they're the ones that you can circle on a calendar or
measure on a clock. So "Tuesday" or "May 25th" or "4 AM" are all absolute
times, and the ever-changing now will eventually catch up to them and then
pass them.

Relative times are ones measured in relation to when "now" is - so "5 minutes
ago", "tomorrow", "next year" are all relative because the specific time they
reference will change - "5 minutes ago" might have meant "4 AM" when you said
it, but eventually it will mean "noon" or "1:47".
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2019-05-29T01:31:53.237
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An _absolute_ time or date is a time period that will refer to the same time,
regardless of when it is mentioned. These are typically exact times (on the
same day in the current timezone unless otherwise stated) or calendar dates.
In Japanese these are usually marked with the に particle but this can be
omitted in casual conversation. For example:

午後6時15分 (6:15pm)

6月25日 (June 25)

正午 (midday)

A _relative_ time refers to a different time or day depending on when it is
mentioned. In Japanese these can be followed by は, が, or no particle at all.
They're often given at the start of a sentence. For example:

一時間後 (an hour later)

一年前 (a year ago)

今日 (today)

明日 (tomorrow)

再来週 (the week after next)

Note that both relative and absolute times can be used with から (beginning) or
まで (ending) for time intervals.
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2019-05-29T07:05:41.833
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ConMan and Tom Kelly have addressed the question you have asked in the
subject/title of your post. As for the rather different one in the body, it
sounds to me as if your source is simply using "relative time" for times
measured in hours or smaller units of time ("three seconds ago," "forty-five
minutes from now," "forty-eight hours ago," etc.) and "relative date" for
times measured in days or larger units ("the day after tomorrow," "two weeks
ago," "eight months from now," "the year after next," etc.").
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answer