II.b) Precursors of the Theory of relativity

At the end of the 19th century, Classical Mechanics from Newton and from Galileo’s relativity worked reasonably well. However, there were still things that did not quite fit, there were still things that did not quite fit, such as electromagnetism topics, nature of light or electromagnetic waves, their speed, and the elemental structure of matter.

These intriguing areas of physics impelled scientists to cultivate new solutions. One could say that nowadays the same is happening with other problems. Maybe it has always been that way.

By comparison with the rest of known types of waves, it seemed that electromagnetic waves needed a material through which to propagate.

This model based on the concept of aether, a supporting medium of light. To confirm the model, they hoped to find the absolute velocity of an object dependent on a universal frame of reference, given that the Earth was no longer the center of creation, and Ptolemaic system had long since been discarded.

 
 

II.b.1. Maxwell’s equations of the movement of electromagnetic waves

Maxwell’s equations describe movement of electromagnetic waves. Given that it is a wave motion, Maxwell’s equations incorporate an undeniable mathematical complexity due to the sinusoidal waves form.

In 1869, Maxwell’s equations made possible theoretical calculation of the speed of light, or electromagnetic waves in general. This drove scientists of the time to search for elements that would strengthen the classical model and would incorporate the dynamics of light propagation.

Hertz, in 1887, confirmed experimentally the speed of light determined by Maxwell’s equations.

What no one expected was that, what Maxwell had calculated for a supporting medium of light with a concrete set of conditions, would end up integrated as a postulate or axiom of Special Relativity, independently or without needing a medium.

Whilst aether remained undetected, they assumed its non-existent; the final error came with Einstein’s Theory of Relativity and its interpretation of Michelson-Morley experiment.

In other words, he included propagation of electromagnetic waves in vacuum independently of its conditions. Curiously, he later incorporated a different effect of the condition of gravitational intensity using the Equivalence Principle in General Relativity.

On Wikipedia, I saw something interesting that I have heard many times. It said that Maxwell’s electromagnetic wave equations predicted a wave that, contrary to the ideas of the time, did not need a medium for propagation. This electromagnetic wave could transmit in a vacuum due to the mutual generation of electric and magnetic fields.

I have finally understood the error that is made in this affirmation; in Maxwell’s time many things were thought of, some correct and others not. In this case, they accepted a priori the content of the incorrect notion of the electromagnetic wave equation, and therefore the conclusion was just as incorrect. In other words, on the one hand they did not accept that a wave needs a supporting medium through which to propagate, and on the other, they embraced the incorrect idea –electromagnetic waves transmit in a vacuum.

The idea about mutual generation is better not to comment. Anyway, it was an ingenious idea…

Global Mechanics understands the so-called electric field and magnetic field of the electromagnetic wave equation as the perpendicular components necessary to define torque. This is because torque is in the perpendicular plane to that of the direction of wave propagation. In other words, the difference between magnetic and electric field is completely conventional and for historical reasons.

Of course, it was not only in Maxwell’s time, but also in almost the whole of the 20th century –and indeed, even now– that scientists still confuse vacuum with nothingness –like on Wikipedia–. However, some quantum theories are beginning to recognize openly that classical vacuum is not as “empty” as thought.

Moreover, a dangerous epistemological problem of the philosophy of science acts. In order to accept a proposition, the argument is that because its acceptance in the past, it must be true now. Interesting indeed!

In the section Properties of light waves or photons of the book Global Mechanics, I explore the relative movement of electromagnetic waves and Maxwell’s equations more in depth.