An example of a historical scientific idea that would now be considered an alternative conception:
"When an electron is in motion it produces a disturbance in the ether which surrounds it. If its motion is rectilineal and uniform, this disturbance is reduced to the wake I spoke of in the last section. But it is not so if the motion is in a curve or not uniform. The disturbance may then be regarded as the superposition of two others, to which Langevin has given the names of wave of velocity and wave of acceleration.
The wave of velocity is nothing else than the wake produced by the uniform motion.
As for the wave of acceleration, it is a disturbance absolutely similar to light waves, which starts from the electron the moment it undergoes an acceleration, and is then transmitted in successive spherical waves with the velocity of light."
Henri Poincaré (1914) Science and Method (trans. Francis Maitland) Dover Publications, 1952.
