Eli5: Why, if at all, does it seem like the years go quicker as you get older?

Question

I hear a lot of people making that remark, that the years go by quicker as you get older.
For me, at least, it seems like that’s only the case if nothing much changes in my life in that year.
To me, years seem to feel like they go slower if there’s lots of new/different things happening.

In: 348

Answer 1

Because they are increasingly smaller fractions of your lifetime. When you are 5, each year is 1/5th of your entire life. When you are 25, each year is only 1/25th of your life. Humans do not have any absolute sense of time, we can only measure it’s passage in comparison to other things, and while the time it takes for the seasons to change is unchanged, so a year “is” the same duration, chronologically each year seems like a smaller and smaller amount of time because each one is smaller in proportion to our experience.