I noticed this as a teenager. And came up with the "ratio" theory on my own.<p>For example, I was thinking, when I was young (say 7 years old), summers seemed to have dragged along forever. Summer vacation was a loooong time. By the time I was in the 8th grade, it seemed to fly by.<p>So the idea goes by like this:<p>* We measure time interval compared to the number of intervals we have already experienced.<p>* For one 1 year old each new month is a 1/12 of their life-time, so it seems like a pretty long time.<p>* For a 80 year old, 1 month is 1/960 of their lifetime. A new month, will fly by because it is a much shorter time.<p>* To have the same subjective experience of a month passing, an 80 year old would need to spend 6+ years or so (80/12)<p>* To have the same subjective experience as an 80 year old's month, a 1 year old would just wait for about half a day to pass by.<p>Totally bogus idea probably, but I was proud of myself for figuring it out on my own back then.