We had finished post scientific method without filling the void left by the shortcomings of the inductive method. Epistemological reflection on the natural sciences, especially physics has acquired great force after the affirmation of Theory of relativity of Albert Einstein, which gave a new methodological approach to theoretical physics and the philosophy of science.
Foto di Albert Einstein
Once again the winning move of Einstein was adopted heuristics and his great insights. La teoria della Relatività di Einstein non salta fuori da un cilindro magico o da una mind supernatural, but is the synthesis and enrichment of knowledge circulating among scientists of. For example, the transformations of space and time cordinates, They had already been discovered by Hendrik Lorentz (1853-1928) from which they took the name (Lorentz-FitzGerald)
From these formulas it obtains the famous laws of length contraction and time dilation of moving objects. The problem is that Lorentz had not given a plausible explanation, which would accord with the physics of time and those formulas they seemed to make little sense, apart from be highly counterintuitive. Albert Einstein Instead wonders (as he had done Galileo Galilei) how can verify these physical laws through experimental procedures . How do I measure the length of a body moving at near the speed of light relative to the observer?
Per Lorentz, the effect would not be verifiable because, the measuring instrument, that moves together with the object would have suffered the same contraction of the object, and then the effect would be somehow canceled. If it took a meter on a spacecraft moving at nearly the speed of light, the meter would undergo the same contraction of the object.
Instead Einstein found to an objective measure obtained by sending an electromagnetic signal from an observation point fixed against an object that is moving at near the speed of light. By measuring the time of return in which the light beam is reflected from the two ends of the object, I can get an objective measure of the object.
Therefore, a possibility that we have to measure the length of a moving object is to send a ray of light, wait for his return and measure times. From this starting point and by two simple postulates (also the science It has its dogmas) proceeding heuristically, eventually formulates special relativity.
But let's step back. A key event for modern physics is the formulation of the general theory of electromagnetism. Main protagonists Ampere, Faraday, Hertz e Maxwell. The latter, in particular, He discovered the electromagnetic nature of light phenomena. Said in a simple way, the light is an electromagnetic field. The problem is that in those days, It is imbued with the physical mechanism, thought (and our players have never doubted) the light to propagate needed a substance called luminiferous ether.
The movement is transmitted only through the matter, with actions force between adjacent elements.
The air must be formed by an invisible substance that allows the movement to propagate.
Each body moving in’universe It produces an ether wind that moves at the same speed of the moving body, but with the opposite direction.
We try to follow this simple reasoning. If the land is surrounded this mysterious ether, and as we know revolves around the sun with a velocity v = 30 km / s (which corresponds to a wind of ether with the same speed but opposite direction), and if we were to send a ray of light in the direction of the motion and one perpendicular to it, the speed of the light rays would be different. Imagine giving a kick to a ball on a train in the direction of motion of the train. To an outside observer, the ball has the speed of the train, the more the speed that has been imprinted with calcium. In this way, if we measure the speed of the wave in the direction of motion of the earth and that of a beam that moves horizontally in relation to it, the two speeds should have a difference (according to the Maxwell equations) proportional to (v/c)2.