The Day the Universe Changed - James Burke [137]
The scientists themselves were more worried than impressed by all this. During the process of electrolysis an electric current produced a chemical action; however, a chemical solution of lead acid would produce current. Was there some connection between chemistry and electricity?
The idea of connections between things was very fashionable at the time, especially in Germany, where the Romantic movement had produced the school of thought known as Naturphilosophie. Originating with the philosophy of Kant, whose dialectical view of nature explained all phenomena as the result of opposing forces reconciled into synthesis, Naturphilosophie held that nature was in perpetual struggle, that all progress came from synthesis, born of stress, and above all, that everything was related to everything else. The puzzle of the attractive and repulsive effects of electricity and magnetism was irresistible to the Naturphilosophs.
In 1820 a Dane called Hans Christian Oersted, educated in Germany and much influenced by Naturphilosophie, decided to examine electricity and magnetism to see if they were related. Oersted followed the tenets of Naturphilosophie by putting the electricity under stress. He forced it along a highly resistant platinum wire. Sure enough the wire behaved like another phenomenon: it glowed like lightning. More important, however, it affected a nearby compass needle as though the current were a magnet. Oersted showed that the magnetic effect of the electric current circled the wire, in space. There was some kind of force at work around the wire.
The discovery of electromagnetism. Oersted, Professor of Physics at Copenhagen University, first succeeded in disturbing a magnetic needle with an electric current during a lecture demonstration.
Young’s light fringes. The light (right), goes through two pinholes. When it emerges, instead of continuing unchanged, it interacts like ripples, alternately enhancing and cancelling itself, producing light and dark bands.
In an apparently unrelated set of experiments earlier in the century, Thomas Young and Augustin Fresnel had shone light through narrow slits set at varying distances from each other, and proved that the light emerging from the slits interacted much as did ripples on a pond, by adding to or cancelling each other and producing interference patterns accordingly. Where the waves cancelled each other out there were black bands. Light plus light made dark. It began to look as if the old Newtonian idea that light was composed of fiery pieces of matter was wrong, and that light travelled in waves.
By the time Oersted began to experiment with his wire and needle, Fourier and Fresnel had developed comprehensive theories to explain the transmission of heat and light by wave form, and had shown that polarised light travelled in transverse waves. But in what medium were the waves travelling? The same question was soon to concern the researchers of electricity and magnetism.
Their first problem was that the new interactive forces did not fit Newtonian mechanics. They did not move straight from the centre of one body to the centre of another, as did gravity, but along the curved lines of force. The force was purely electrical, and unaffected by the medium through which it passed. Did the medium affect its flow? With no simple electrified bodies to examine, only a ‘current’, where were they to begin? It became a matter of urgency to be able to take measurements, to turn the mystery force into a quantifiable phenomenon.
In 1879 Andre Ampere put two live wires next to each other and saw that when