My opinion is much more mathematical. The first year of your life is 100% of your experience when you turn one. The second year is only 50% of your experience. Then by the time you're fifty, each year is only 2% of your total experience at that point. They accelerate because despite what people believe, we don't have a real grip on the passage of time. I think we rely more on an internal sense than others believe, and that internal sense is based on your own experiences.