Wolfgang Korsus Dipl.-Ing. NT , Astrophysikist
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Website: Wolfgang.Korsus.net
I like to come back to my last sentence of the last chapter.
A Christian Ørsted in Copenhagen stated electricity and magnetism occur together.
Yes, to this can be said, certain materials allow a „current flow“ exactly between „plus“ and „minus“ ; thus two opposite charges !
That is, we can build an electric circuit. Also, Ørsted had noticed that magnets aligned themselves perpendicular to the direction of the current, as if the current had created magnetic lines of force around its direction of flow. Continuing, it was still possible to imagine endless magnetic lines of force, -closed-, circles wrapped around the direction of the current. A further explanation followed from it, namely that the cutting of a magnet resulted in two new ones and cannot lead to an isolated pole.
This means in the end nothing else than that electric and magnetic forces are in fact closely related. The electric currents produce magnetic fields, and moving magnets induce electric currents on their part.
This points to a unified theory of electromagnetism, which is confirmed by the very famous equations of the Scottish physicist James Clerk Maxwell. There the unification of the theory of electricity and magnetism is confirmed. Maxwell also showed that a long-distance effect of electromagnetic charges is possible. Thus, a variable electric field produced a magnetic field; likewise, a variable magnetic field induced an electric field. The combination of both, electromagnetic fields, got therefore a perfect independent existence, without the necessity of currents or magnets.
Continuous waves form a rather simple solution of Maxwell’s equations, similar or comparable to the vibration of a string or a wave on a lake. The remote effect searched for consisted therefore of electromagnetic signals, which propagate like waves. They cross the space with constant speed, which one could measure – and thus one found the known speed of light.
But hello, the basic question „What is light?“ was thus answered: light is simply an electromagnetic wave propagating through space, and the different colors correspond accordingly to the different wavelengths.
If we consider more than the visible range, s today we know electromagnetic radiation in both directions: radio waves once longer wavelength than that of infrared radiation and the X-rays shorter wavelength known as ultraviolet radiation. By the exchange of such waves also distant electric charges can interact with each other remotely .
If one approaches today the topic „electromagnetism“ more near, one finds out, it determines actually our whole life and its forms are hardly manageable.
Dear reader, please do not forget the times of Faraday and Maxwell, the topic was pure basic research at that time. Some said, pure spinning of a few scholars. So hardly noticed by the public.
Like almost every scientific story, these ideas of Faraday and Maxwell had a catch to be considered.
Let us now approach the subject of „waves“ cautiously and please not hastily. It was said : …distant charges communicate by waves – so what is excited to produce such waves? Let’s look at our everyday life. There it is e.g. violin strings or a water surface or the density of the air. But the question remains, what vibrates in empty space?
Now there were some gentlemen of science who brought the ether into the world of physics, it should be an invisible medium which fills the whole allegedly empty space. Of course, this sounded very reassuring for all those who considered a completely empty space as unnatural anyway. I mention now briefly the French philosopher Blaise Pascal, who meant even „the nature is the empty space abhorrent“ – strange statement ! Also the Evangelista Torricelli in Italy, who succeeded in removing all air from a container, reaped a tired utterance from Pascal, who only meant that the absence of air was not synonymous with empty. Let’s stay with the ether……because Robert Hooke had introduced it in 1665 as the „medium for light“; he had imagined a pulse of light like a stone thrown into water, this spread out with concentric waves.
Still another known example from our today’s world that also scientifically touches the investigated reality : thus not correctly……
a tsunami wave, generated by a seaquake deep under the sea level and spreads then up to distant shores, so an electromagnetic change of state reaches most distant receivers by an electromagnetic tsunami wave in the ether sea. Strange example !
So let’s detach the ether and say clearly: Ether turned out to be a dead end in physics. Even Hooke up to Einstein have tried their luck with it like many well-known physicists, but always with quite limited success.
I just don’t stop and ask the next „ether question“ . Is the aether something
stationary, or is it even dragged along by moving stars?…..further, …possibly the earth produces an ether wind on its orbit? Does matter perhaps consist only of aether vortices? The existence of the aether made long-distance effect by waves possible.
But the aether suffered from the fact to be simply a substance and nevertheless not to influence the movement of the celestial bodies essentially. So it had to come to a final end of the ether and this happened by one of the most famous experiments of physics. Naturally this was also carried out by someone. So in the years around 1880 by the American physicists Albert Michelson and Edward Morley .
They intended to prove the existence of the invisible medium.
So if the light spreads everywhere through the ether with constant speed, then follows from it: it should be slower in the direction of the earth movement than perpendicularly to it and in addition is to be noticed…The faster the earth turns, the slower would be a light beam following the movement.
These two, Michelson and Morley constructed an interferometer, in which a light beam is divided in two; afterwards both partial beams must cover the same distance, one along the earth movement, the other perpendicularly to it. This should be done with a suitable mirror arrangement, because they then meet again at a certain point at the end. I represent it schematically for this arrangement in the following picture.
What has happened there and what has been clearly shown with it.
The, quasi any, light beam is directed to a partially transparent mirror M. One part is reflected to mirror 1 and goes from there to the detection device, the other to mirror 2 and then to the detection device. It is essential to note, the direction mirror 1 to the detection device is chosen south-north, that from the light source to mirror 2 west-east. Without any doubt, mirrors 1 and 2 are equidistant from the center mirror M.
Now it was expected that the earth rotation slows down the beam directed to mirror 2. Consequently, the two beams would arrive at the detection device with unequal phases – the wave trough of one meets the wave crest of the other. Thus, a detectable interference pattern must be generated……
…..but guess what, the result obtained was extraordinarily disappointing for the two physicists: they could twist and turn they found no effect at all, the waves always arrived in phase. It didn’t matter which way they turned their apparatus, the speed of light always seemed to stay the same….no not seemed, it always stayed the same. There was no hint of any form of aether. The ether should be buried with it !
It was not left out that despite a phase of protracted search for a way out, in which many physicists were involved, finally Albert Einstein spoke then twenty years later a power word and banished the idea of the ether from the physics.
This applies at least to light and electromagnetism; in the areas of gravity and the expanding universe, such ideas still haunt us today…. extremely strange and belong to the topic of science fiction.
Let’s go back to Maxwell’s equations, from them follows that light propagates through space with constant speed – and that with a universal speed of light. A statement which is much more far-reaching than it seems to us at first: we like to say such a behavior is simply not in accordance with our world of experience. Let us look at this example :
A car driving at 100 km/h moves only at 70 km/h for the person driving at 30 km/h in the same direction. Further with this statement, two cars driving with 100 km/h next to each other in the same direction do not move relative to each other at all ! And still something to think and let work, let times in a moving train a coin fall, it falls straight to the ground; train, traveler and coin rest relatively to each other, but for an observer standing at the platform the train moves with high speed.
Thinking further, I say : „Light is quite different“.
There, all observers, regardless of how they move relative to each other, always measure the same speed of light. No matter how fast someone moves, he always measures this certain 300,000 km/s; from this I conclude before a light beam we can neither run away nor catch up him.
I must mention now, in the world of Newton’s laws such a thing is not possible. Because in a fixed world with a uniform time, the speed of light must change for observers who are in relative motion to each other. So to make a constant speed of light possible, we must fundamentally change our conception of space and time. The units of length and time must depend on the observer himself. For if I measure the speed of light here on earth, and an astronaut flying at high speed through space does the same and finds the same value, then his units of measurement, his meter and his minute, must be different from mine here – and indeed, they are.
A real upheaval of physics was initiated with it, it was Albert Einstein’s theory of relativity, more specially mentioned, his special theory of relativity. Don’t be afraid, this addition special is to indicate that it is valid only in spatially limited areas of the universe. In addition and including follows an important extension on the whole cosmos, of course including gravity, it is the general relativity theory – I add, also this one a result of Einstein’s imagination….My respect…
Einstein established for the special relativity theory a mental relations between the just proved universal speed of light with an equivalence principle established four hundred years earlier. It came from Galileo, he had demanded that the laws of physics must always remain the same for all observers who move uniformly relative to each other.
Let’s express it in a more understandable way, if I measure how long a stone needs to fall one meter, once in my laboratory and another time in a fast train, then the two results must agree. It was clear to him, i.e. to Einstein: This is an equivalence and in order to preserve this equivalence and at the same time to obtain the same universal speed of light for all observers moving relative to each other, the ideas, i.e. ours, of space and time had to be changed. Space and time would have to be actually connected and the scales would have to depend on the speed of the observer. Back to Newton, in his world there was a uniform time, it was the same everywhere, and one could imagine that two events happened simultaneously.
But in the relativistic world, synchronization over long distances is not possible, and what is earlier there for one observer may be later for another. …Easy, not to believe…
The relativity theory said still more what was very significant, namely no body can ever reach light speed. Again I go to Newton and his law of force says : an increase in force leads to an increase in acceleration. Further one would conclude that one can bring each mass on arbitrarily high speed, thus faster than the speed of light. But now Einstein comes forward again and has shown that Newton’s law is changed if the speed of the mass comes near the speed of light. Say and write, only a part of the force leads to acceleration; a larger and larger part produces an increase of the mass, the inertial behavior of the body. So in our normal world, all velocities are so far below the speed of light that we can safely neglect such relativistic effects and therefore assume a velocity-independent inertial mass.
Watch out and pay attention……in high-energy accelerators, such as the Large Hadron Collider at the European Center for Particle Physics CERN in Geneva, where protons are brought to about 95% of the speed of light, their effective mass is then more than three times their rest mass. From this result it is clear that we can never bring a massed body to the speed of light – that would require a truly infinite force. Furthermore, it must be said, nothing and nobody can ever catch up with a beam of light in empty space – light remains the fastest signal in the universe. So it is and this is valid without contradiction.
We now know that the light from the stars that we see today has been traveling for many years, electromagnetic radiation in an empty space, without any ether, propagating at 300,000 km/s, no matter who measures it. This leads I can return to the initial question and to my initial question:
Why is the sky dark at night ?