The scientific explanation for time seemingly moving slower when you were young is easily explained with a simple calculation: When you were five, one day was 1/1826 of your life. At eighteen, it was 1/6574. At 50, it's 1/18 264... So, compared to your past days, one day at the age of five is equal to ten days at the age of fifty. Similarly one day at the age of eighteen is equal to almost three days at the age of 50. You can change that to per milles if you like. Shortly, the more days you have behind you, the shorter a single day seems compared to the total amount of days you've lived.
