4. THE ETHER AS A CARRIER OF ELECTROMAGNETIC PHENOMENA
 
   In the middle of the 17th century, Descartes presented the idea of the existence of the ether as a carrier of light. This idea was a predecessor to the wave theory, first proposed by Hook in 1667, but first clearly formulated by Hygens in 1678. Their great contemporary Newton was the author of the opposite doctrine - corpuscular theory. This theory, which dominated for a hundred years thanks to Newtonian authority, claims that glowing bodies radiate tiny particles, corpuscles which move according to the laws of mechanics. The wave theory, however, established the analogy between the propagation of light and wave motion on water or sound waves in the air. Because of that it supposes an elastic medium which fills all the empty space and transparent bodies. special particles of this substance simply oscillate in relation to their balanced position and in such a way make the transfer.
   At first it was supposed that there was not only one but a whole series of ethers: optical, thermal, magnetic etc. For each phenomenon a corresponding ether was assumed as a carrier. At the beginning all these ethers had nothing in common. But as time passed a connection was found between phenomena from different areas of physics, phenomena which had not seemed to be related. Finally the ether appeared as a carrier of all physical phenomena, occurring in space without matter. The ether hypothesis was given great support by the revelation that light presents the oscillating electromagnetic process. Keeping in mind, that light as electromagnetic oscillation process comes to us from far away stars, passing through enormous tracts of empty space, and since most physical phenomena and influences propagate throughout the cosmic space, it is quite logical that the hypothesis was reached that this space is not empty, but filled with a fine, weightless substance - called the ether, which is the carrier of all phenomena and influences. Further more, it is assumed that ether is isotropic, absolutely quiescent and can penetrate anywhere and that coarse cosmic bodies and others material bodies move through it. As such, the ether would be suitable for the absolute inertial system, and the coordinate system connected to the ether would be the absolute coordinate system where the velocity of light would be equal in all directions. The presentation of electromagnetic phenomena would be simplified in it. All positions and motions of bodies in the universe could be considered and calculated relatively to that system, which would make the presentation and calculation of motions much simpler.
   Einstein was the greatest opponent of the idea of the ether's existence. A large part of his opus is related to the ether.
 
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