When you’ll turn up your eyes to the moon…
Is this title too poetic for a blog science’ passionate?
Tell me about it 🙂 So if it bother you or give you a strong particular impression shield it or leave it behind – if you can handle that – until the end of this post.
In fact, yesterday I’d the idea for this post having the usual evening promenade in my area with my beloved retriever. He was searching for something, struck by the smells and curiosity of the suburban areas of a town that despite being the capital of country is becoming less and less illuminated (perhaps to avoid any hope of re-qualification?) and thrown to the common sense of its inhabitants. But, in many ways, STILL with something to offer to those who can pick the positive side of this vast urban landscape that can be accepted or not.
In fact, the main source of light was the one coming from dim lunar rays, the uncovered sovereign on a row of street lamps trying to keep us some company. A presence able to make us a surprise, if they – in the upcoming future – will decide to turn on in their automatic scheduled time. Perhaps a curious metaphor of the vacuum around us and the far noisy houses due to continuous vacation time.
As you may have noticed, I want to write about void.
Newton’s law of universal gravity postulates the presence of attractive forces that act with no delay in time and between bodies that are separated in space. The magnitude of these forces depends on the separation of the bodies, falling off as the square of the distance. Important passages that cannot be replicated in space where the absence of bodies cannot allow any transmission of force. Newton’s dedicated lot of time, days of reflection, pages filled with formulas and alternatives postulated by his own hand, such this one that he do not hesitate to define an ‘absurdity’:
That one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that, I believe, no man who has in philosophic matter a competent faculty of thinking could ever fall into it.
The experience help him to depict the definition of what might be a visualization, a dance of concepts through space and time, beauty and balance. Equations have to display this precise perspective in an explicable system.
Physics proceeds with fine observations and experiments that can reflect the standards underlined by the hypothesis and deductions of a clear methodology that allow to have precise calculation of the law taken in reference. This is the first main reason why Newton’s followers became soon more “newtonian” that he was in his first career, when he loathes the void if he might explain how forces act at a distance through an empty space and fall off as the square of the distance, so when the firsts are four time weaker at twice the distance, and so continuing in that reasoning.
At the end of his Principia this expression are for us a remarkable source of reflection on his perspective at the time. Probably he felt sorry for us to haven’t yet the clue for this subtle and complicated element:
And now we might add something concerning a certain most subtle Spirit, which pervades and lies hid in all gross bodies; by the force and action of which Spirit, the particles of bodies mutually attract one another at near distances, and cohere, if contiguous; and electric bodies operates at greater distances, as well repelling as attracting he neighboring corpuscles; and light is emitted, refracted, inflected and heath bodies. And all sensation is excited and the members of animal bodies move at the command of the will, namely, by the vibrations of this Spirit, mutually propagated along the solid filaments of the nerves, from the outward organs of sense to the brain, and from the brain into the muscles. But these are thing that cannot be explained in few words, nor are we furnished with that sufficiency of experiments which is required to an accurate determination and demonstration of the laws by which this electric and elastic Spirit operates.
This void based theory of forces at a distance has no trouble to account for another demonstration that led to Faraday’s work that up to Maxwell’s words “saw lines of force” traversing all space and where mathematicians saw centers of force attracting at a distance, Faraday saw a medium when they saw nothing but distance and sought the seat of the phenomena in real actions, going on in the medium.
I think that at this point you had the right impression! Faraday’s lines of (magnetic) force 🙂 In other words, iron filings, moving freely on a thin sheet of paper help over a bar magnet, trace out a striking pattern. The iron filing line up under the influence of the bar magnet close to them, to align into a space-filling system of curved lines. This effect demonstrate how each shred of iron perceive forces from the poles of the magnet, acting through empty space to align accordingly.
Faraday’s interpretation was that the filings merely reveal this state of a space-filling medium which continue to be there, despite the presence or absence of the filings or in this specific case even the magnet that stirs up that medium. Namely, Faraday’s approach led him to several remarkable discoveries based upon his theoretical ideas and experimental procedures. This is the case when magnetic fields change in time produce magnetic fields and Faraday’s law of induction (as it’s called) gave a big stimulus to tech underlying how design of electric motors and generators can make a difference in physical reality.
Then was the turn of Maxwell, coming out in this frame, with his model able to calculate how an excitation in electric and magnetic fields begin a life on its own, with the fields dancing as a pair cause they go together and inspire each other. In fact this combination allow dramatic new possibilities able to vary in time and speed. No, there is no coincidence in this aura: electromagnetic disturbances are light, and light is (at the bottom) the element that interfere in the electric and magnetic field.
Imagine how excited he was after this discovery! Rather to tell and firstly because he was able to go a piece further than his peers, creating a fantastic unification of electromagnetism and optics.
Have a great day, and keep passionate on science until the next post 😉