Models of the Aether Chapter 13 By Michael Dolan.
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Transcript of Models of the Aether Chapter 13 By Michael Dolan.
Newton Disagreed with Hooke’s notion that light
was a wave
Before Principia: “All space filled with an aether of variable density.”
Newton In Principia: Kepler’s 1st and 3rd laws show
that a dense aether does not exist
After Principia: Associates existence of an aether with his belief in God’s omnipresence
Huygens Against Corpuscular
Theory: When two beams cross there is no scattering
Believed light waves are propagated through a very elastic medium
His views were not widely accepted
Lesage Instantaneous propagation of gravity
= NO need for aether
= NO wave theory
= support for Corpuscles Corpuscular
explanation of gravity Eventually disproved
Stellar Aberration Discovered by Bradley in 1728 Used as support for corpuscular theory Proves speed of light is constant
Euler Proponent of Wave
Theory Light sources do not lose
mass Claimed gravity was also
explained by the aether that is responsible for the propagation of light
Young Constructive and
Deconstructive interference of light waves
Used analogy with water waves
Transverse vibrations
Wave Theory of Light Started by Fresnel, uses aether to explain
polarization Measurement of the speed of light in water vs.
speed of light in air Supported by Poisson’s “Bright Spot” experiment
The Elastic Solid Aether Navier, Cauchy and MacCullagh’s
mathematical equations Riemann unifies optics and
electromagnetism Boussinesq proposes one aether, which is
present (and the same) everywhere Result: the Electromagnetic Theory of Light
Electromagnetic Aether Faraday’s study of magnetism He breaks from traditional scientific thought
of his day
Thomson Gave legitimacy to Faraday’s concept of an electric
medium, “Faraday saw a medium where they saw nothing but distance”
Equated lines of (electrostatic) force to lines of heat flow
(Poor) reproductions of figures 13.3 and 13.4 on p. 189 in the text
Thomson (cont’d) Analogy between E field and an elastic solid Described B field as rotary phenomenon Mechanical model for aether
Maxwell (cont’d) Vortices imply viscosity Adamantly defended existence of the aether
Whether this vast homogenous expanse of isotropic matter is fitted not only to be a medium of physical interaction between distant bodies, and to fulfill other physical functions of which, perhaps, we have yet no conception, but also… to constitute the material organism of beings exercising functions of life and mind as high or higher than ours are at present, is a question far transcending the limits of physical speculation.
Michelson-Morley Experiment Produces the null result Challenged the belief of an absolute aether
http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/mmexpt6.htm
Saving the Aether Lorentz-Fitzgerald
contraction hypothesis, 1904
Kennedy-Thorndike experiment, 1932
But both experiments merely provided ad hoc parameters
Saving the Aether Aether Drag: lessens magnitude of aether’s
effects, but fails to explain other phenomena Experiments by Hamar and Hoek again find
the null result
Fall of the Aether Einstein’s theory of
relativity No longer needed one
universal frame, and therefore no longer needed the aether either
Light in a Vacuum? Einstein solved this
problem as well Considered light a
wave-particle This eventually led to
the beginning of quantum mechanics