📜 Origins of the aether concept
Wave theories of light and the aether
1600s–1800s
- Huygens and later Fresnel champion wave optics, motivating a medium — the aether — to carry light.
- James Clerk Maxwell (1860s) unifies electricity and magnetism; light emerges as an electromagnetic wave in the aether.
🧪 19th-century experimental puzzles
Clues from key experiments
1851–1887
- Fizeau (1851): light in moving water shows partial dragging, suggesting complex medium behavior.
- Michelson–Morley (1887): famous null result — no detectable aether wind at Earth’s surface.
🧠 Early explanations
Dragged vs stationary aether; invariance ideas
1850s–1890s
- G. G. Stokes: proposes a dragged aether to fit optical results.
- W. Voigt (1887): introduces transformations preserving wave equations, a precursor to later Lorentz transformations.
- G. F. FitzGerald (1889): suggests length contraction for bodies moving through aether.
📘 Toward a systematic theory
Electron theory and relativistic effects
1890s–1900
- H. A. Lorentz: builds an electron theory with a stationary aether, introducing “local time.”
- J. Larmor (1900): derives time dilation and length contraction within an aether framework.
- O. Heaviside: modernizes Maxwell’s equations; considers velocity-dependent electromagnetic mass.
🧩 Lorentz era
From hypotheses to the Lorentz transformations
1895–1904
- Consolidation of Lorentz transformations to keep Maxwell’s equations form-invariant across moving frames.
- Physical length contraction and time effects viewed as consequences of motion through the aether.
🔁 Transitional ideas
Relativity principle and simultaneity
1900–1905
- Henri Poincaré: articulates the principle of relativity and the conventionality of simultaneity via light-signal synchronization.
- Places Lorentz’s equations on firm mathematical footing (group properties), foreshadowing spacetime ideas.
⚡ Special Relativity
Reframing without a mechanical aether
1905
- Einstein dispenses with a mechanical aether: takes light-speed invariance and the relativity principle as postulates.
- Relativistic effects become kinematic properties of spacetime; LET and SR remain empirically equivalent in many tests.
🌌 Legacy & modern views
Why LET still gets discussed
20th–21st century
- Historical interest and pedagogy: understanding how SR emerged from aether-based attempts.
- Philosophy of time: presentism and neo-Lorentzian interpretations (e.g., appeal to the CMB rest frame for a convenient foliation).
- Mainstream physics uses SR/GR; aether is not required for current empirical models.
See also: Famous Figures of LET for short bios, and your site’s main page Home.