It's all relative... Age does make the years seem to go by faster, but there's a perfectly logical scientific explanation. Figure that summer is 1/4 of the year. When you're 10 years old, one summer is 1/4 of 1/10, or 1/40 (2.5%) of your life. Sure, 2.5% may not sound like much, but consider that it's 2.5% of everything you know in life. As you get older, that percentage goes way down. For example, at just 30 years old, a single summer is 1/4 of 1/30, or 1/120 of your life. That's only 0.83%. So relatively, it is a much shorter time.