Mathematical ratios don't account for the emotional impact described, but time and its scope are viewed differently -- albeit not consciously -- by a youngster as compared to an older person:
One year is 20% of a five year old's life, whereas the same time period is 2% of a fifty year old's life. How does this "reality" account for time's dragging or its flying past us? I once expressed myself algebraically, but I'm no mathematical theorist.
I dunno . . .
CC