The SI unit of intensity is watts per square meter (W/m²), while AU, or arbitrary units, is often used when absolute intensity values are not critical. The conversion from SI to AU is not straightforward, as AU represents a relative scale rather than a fixed measurement. In many cases, knowing the relative intensity suffices, especially for applications like analyzing decay time constants from intensity curves. The discussion highlights the importance of context when interpreting intensity measurements in different units. Understanding these distinctions is crucial for accurate data analysis in various scientific fields.
