Uploaded September 2026 | Updated September 2026, 3 hours ago

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Sir Michael Berry, University of Bristol
What we learn(ed) from rainbows

As well as describing the beautiful physics of a dramatic natural phenomenon, rainbow studies over several centuries have illustrated unexpected connections with other areas of physics and the practice of science more generally. The connections include:
• Numerical experiments when mathematics is too difficult
• Illusions: there is no arc in the sky
• A theory (light rays) being replaced by a deeper one (light waves)
• Decoherence: wave interference blurred by imperfect resolution
• Universal wave decoration of smooth focal lines
• Rainbow waves in water
• Colour theory
• Gell-Mann’s totalitarian principle
• Mathematics of divergent series