|Hypothesis: The older you get, the faster time goes by.
Explanation: The first day you're born lasts 100% of your life up to that point. The second day you're alive lasts 50% of your life up to that point. This pattern continues, and it works out that every day of your life is equal 1/n of your life, where n is how many days you've been alive. So when I was 5 years old, I had been alive for ~1825 days. The day of my birthday was 1/1825 of my life. Let's make it even easier by using years. When I was 5 years old, the time between my 3rd and 4th birthdays was equal to 1/5 of my life, or 20%. When I was 20, the time between my 3rd and 4th birthdays was equal to 1/20 of my life, or 5%. So when I'm 100, the time between my 3rd and 4th birthdays will be equal to 1/100 of my life, or 1%. A day when I was 2 lasted for 0.137% of my life. A day when I was 20 lasted for 0.0137% of my life.
Conclusion: The older you are, the smaller of a percentage of your life is taken up by an equal amount of time. Therefore, you can't say, "This has been the longest day of my life." It's just not true. #math