Well, it turns out that the amount of UV radiation, UV light, where UV stands for ultraviolet absorbed by DNA molecules, increases as the DNA dissociates. So as we shine light onto our solution, as we heat that solution, eventually that solution will begin to absorb more and more UV radiation. And we can plot that on a graph. So if the y axis is the relative absorbance of light, and because we're talking about UV radiation, that means the wavelength is about 260 nm, which falls exactly in the spectrum of UV radiation. So we go from one to about 1.4. And so as we increase along the y axis, more and more light is actually absorbed by the molecules in our solution.