What the work claims
That crystals can be modelled as stacks of parallel atomic sheets; that X-ray diffraction patterns arise from phase-coherent reflections off those sheets; and that the geometry of those reflections encodes interplanar distances.
How it was done
William Lawrence Bragg derived Bragg’s law from a physical insight about phase relationships in X-ray reflections from parallel atomic sheets. William Henry Bragg built a rotating-crystal apparatus to measure reflection angles and intensities. They used crystal density and the Avogadro constant to determine X-ray wavelengths from different metallic targets.
What holds up
Bragg’s law holds as a necessary condition for constructive interference from periodic atomic planes. Their measurements of interplanar spacings in simple crystals — using rotation, film detection and density-based wavelength calibration — are reproducible and physically sound.
What does not
It did not determine structures of complex molecules, proteins or biological macromolecules. It did not resolve atomic positions beyond simple crystals. It did not establish chemical bonding, electron distribution or dynamic behaviour.
Why it matters beyond the lab
It turned crystal structure from a speculative geometric idea into a measurable physical quantity — enabling later determination of salt lattices, metals, silicates and eventually DNA, but only after decades of instrumental and computational extension.
Is it worth your time
Yes. It established the first quantitative, experimentally grounded method to infer atomic-scale structure from diffraction — a foundational capability for physics, chemistry and materials science.