- Why did the Nobel committee treat Finsen's work as establishing a general principle rather than just a local remedy?
Optics and Photonics
The behavior and manipulation of light.
- Why did increasing the brightness of light below a certain frequency fail to eject electrons from a metal surface?
- How did Einstein's idea of light quanta resolve the frequency-threshold puzzle that classical wave theory couldn't explain?
- What did Reginald Fessenden actually broadcast on Christmas Eve 1906?
- How does amplitude modulation differ from simply switching a carrier wave on and off?
- How did Lippmann's photographic plates record colour without using any dyes or filters?
- What everyday phenomenon shares its physics with the way Lippmann's plates captured colour?
- What did Gullstrand's dioptric equations calculate that earlier descriptions of the eye had only approximated?
- How did Gullstrand's exact model of the eye's optics change the design of corrective and contact lenses?
- Why do X-rays reflected from successive crystal planes reinforce each other only at specific angles?
- How does treating a photon as having momentum explain the Compton effect's wavelength shift?
- Why can't an ordinary microscope see particles smaller than the wavelength of visible light?
- How did Zsigmondy's ultramicroscope let him detect particles too small to be resolved directly?
- Why does a tiny fraction of light change wavelength when it passes through a transparent material?
- Why can't optical microscopes resolve detail finer than about half the wavelength of visible light?
- What did Edgar Adrian discover about how nerve fibres encode signal strength?
- Why did cyanoacrylate's extreme stickiness make it useless for the optical lenses Coover needed?
- Why were transparent cells nearly invisible under a conventional light microscope before phase contrast?
- How does phase-contrast microscopy convert an invisible phase shift in light into visible contrast?
- How does a dropping mercury electrode reveal what ions are present in a solution?
- Why do different ions produce characteristic steps in current as voltage rises across a polarographic electrode?
- What practical uses did polarography find in industrial and clinical chemistry after Heyrovsky developed it?
- Why did it take thirty-seven years between Heyrovsky's discovery and his Nobel Prize?
- Why can't X-rays be focused with conventional mirrors, and how did grazing-angle mirrors solve the problem?
- Why did nonlinear optics turn out to be useful for probing matter rather than just generating exotic light effects?
- Why can electrons resolve finer structure than visible light in a microscope?
- How did the corrective optics fix Hubble's vision without replacing the flawed primary mirror?
- What distinguishes coherent laser light from the chaotic light of a candle, according to Glauber's theory?
- How does an optical frequency comb allow scientists to measure the colour of light so precisely?
- How did Haroche keep a single photon bouncing inside a microwave cavity for a tenth of a second?
- What is Abbe's diffraction limit and why did it seem to cap microscope resolution at around 200 nanometres?
- How do horseflies use polarised light to locate water, and why does this cue mislead them?
- Why do dark horses attract more horseflies than white horses?
- Why do dragonflies mistake certain black gravestones for water when laying eggs?
- How can a focused laser beam trap a microscopic particle without touching it?
- What practical problem in biology did optical tweezers solve for researchers handling DNA and bacteria?
- How does optical coherence tomography use interfering light echoes to image tissue structure?
- Why was ophthalmology the first field to widely adopt OCT?
- How does OCT's resolution compare to ultrasound, and what does that let doctors detect earlier?