The model in the article suggests that interest rates can change in a way that is not smooth, but rather with many small jumps. This model, called the gamma model, can better explain how interest rates behave compared to traditional models. The shape of the yield curve, which shows how interest rates vary over time, is influenced by a different kind of volatility in the gamma model. Tests show that this gamma model fits real-world data better than the usual models because interest rate changes are more extreme than expected.