People
The experiments name the people who discovered or explained the physics. Each entry below has a stable anchor, so pages link straight to it — and where a name first appears in the text it carries a footnote with this one-line summary. Listed alphabetically by surname.
Erasmus Bartholin
Danish physician and scientist (1625–1698). In 1669 he noticed that a crystal of Iceland spar (calcite) splits a single ray of light into two — the first recorded observation of double refraction, an early clue that light carries a hidden polarization1. See polarized light.
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David Brewster
Scottish physicist (1781–1868). He discovered the angle at which reflected light is completely polarized — now Brewster’s angle2 — studied the polarization of light by absorption, and invented the kaleidoscope.
Augustin-Jean Fresnel
French civil engineer and physicist (1788–1827). Working in his spare time, he gave the wave theory of light its rigorous mathematical form, explaining diffraction3 and interference in detail and settling the long argument between the wave and particle pictures in the wave’s favour.
Michael Faraday
English scientist (1791–1867). One of the greatest experimentalists in history, he discovered electromagnetic induction and showed that a conductor in an electric field4 develops induced surface charge — the mechanism behind the pearl chains.
Joseph von Fraunhofer
German optician and physicist (1787–1826). Orphaned and apprenticed to a glassmaker, he became the finest lens-maker of his age. He invented the diffraction grating5, used it to measure the wavelengths6 of light, and catalogued the dark lines in the Sun’s spectrum that still bear his name.
William Gilbert
English physician (1544–1603), physician to Queen Elizabeth I. His 1600 treatise De Magnete was the first systematic study of magnetism and static electricity; he distinguished electric from magnetic attraction and coined the word “electric” from the Greek for amber. See pearl chains.
Christiaan Huygens
Dutch mathematician, astronomer, and physicist (1629–1695). He proposed that light is a wave and formulated Huygens’ principle7 — that every point on a wavefront8 is itself a source of wavelets — which still underlies our explanation of diffraction. He also discovered Saturn’s rings and built the first pendulum clock.
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Edwin Land
American scientist and inventor (1909–1991). While still a student he made the first inexpensive sheet polarizer by aligning tiny crystals in plastic, and founded the Polaroid Corporation. Polarizing film now appears in every LCD screen — the same physics as the three-polarizer paradox.
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Étienne-Louis Malus
French army engineer and physicist (1775–1812). Looking at sunset reflected in a palace window through a calcite crystal, he realized that reflection can polarize light, and worked out Malus’s law9 relating transmitted intensity to angle. He died at thirty-six, never knowing the deeper reason his law holds.
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James Clerk Maxwell
Scottish physicist (1831–1879). His equations of electromagnetism (1865) showed that a changing electric field makes a magnetic field and vice versa, and that the pair travel together as a transverse wave10 at the speed of light — proving that light is an electromagnetic wave.
Lord Rayleigh
English physicist (1842–1919), born John William Strutt. He explained Rayleigh scattering11 — why the sky is blue and skylight is partly polarized — discovered argon (winning the 1904 Nobel Prize), and wrote the foundational treatise on the theory of sound.
Thales of Miletus
Greek philosopher (c. 624–546 BCE), traditionally counted the first scientist. He recorded that amber, when rubbed, attracts light objects such as feathers and straw — the earliest known note of static electricity. The Greek word for amber, ēlektron, became the root of “electricity.”
Willis Winslow
American inventor working in his home laboratory in the 1940s. He found that fine particles suspended in oil could change the fluid’s viscosity a thousandfold under an applied electric field — the electrorheological effect, the same field-driven self-assembly seen in electric pearl chains.
Thomas Young
English physician, physicist, and polymath (1773–1829). In 1801 he shone light through two closely spaced slits and saw a pattern of bright and dark bands — a demonstration of interference12 that could only be explained if light is a wave. He also helped decipher the Rosetta Stone. See the double-slit experiment.
Footnotes
Polarization — The orientation of a transverse wave’s oscillation; for light, the direction in which its electric field vibrates.↩︎
Brewster’s angle — The angle of incidence at which light reflected from a surface is completely polarized parallel to that surface.↩︎
Diffraction — The bending and spreading of a wave as it passes an edge or through a gap comparable in size to its wavelength.↩︎
Electric field — The region around a charge in which another charge feels a force; measured in volts per metre.↩︎
Diffraction grating — A surface ruled with many closely spaced slits or lines that spreads light into sharp, widely separated orders.↩︎
Wavelength — The distance between successive crests of a wave; it sets the colour of visible light.↩︎
Huygens’ principle — Every point on a wavefront acts as a source of secondary wavelets; their envelope forms the next wavefront.↩︎
Wavefront — A surface joining all the points of a wave that are in the same phase, such as a crest.↩︎
Malus’s law — The transmitted intensity through a polarizer is I = I₀cos²θ, where θ is the angle between the light’s polarization and the filter axis.↩︎
Transverse wave — A wave whose oscillation is perpendicular to its direction of travel, as with light on the electromagnetic field.↩︎
Rayleigh scattering — The scattering of light by particles much smaller than its wavelength; it polarizes skylight and makes the sky blue.↩︎
Interference — The addition of two or more overlapping waves, producing regions that reinforce (bright) and cancel (dark).↩︎