Stephen H. Yuwono

Light from a lamp or a star, passing through matter, leaves its mark: atoms absorb some colors and let others through. The result is a spectrum — a colored strip with dark lines, like a barcode that reveals the chemical composition. But some atoms and molecules have unpaired electrons — loners that behave unpredictably and complicate calculations.

When chemists calculate the behavior of molecules on a computer, they use approximate methods because exact calculations are too complex. For light atoms, there are well-established benchmarks, but for heavy atoms, where relativistic effects matter, such benchmarks did not exist. It's like checking a ruler against another ruler rather than against a standard meter.