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Speed ​​of light: definition, history and research

Speed ​​of light: definition, history and research


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To be faster than light, is the dream of all super heroes, and not only, but how much does the speed of light measure? And is it possible to overcome this limit? These are questions that we have been asking ourselves for centuries and as our studies continue, we always find new answers. It is therefore interesting to ask ourselves about a magnitude that may seem obvious and banal to us, because if it were not constant, many things could change. Among the many scholars who have dedicated their lives, entirely or almost entirely, to the study of the speed of light, there is also the well-known Albert Einstein.

Speed ​​of light: definition

The speed of light in physics is denoted by the letter "c" because we refer to the Latin in which this magnitude can be defined as "celeritas". By definition it is the propagation speed of an electromagnetic wave and a free massless particle. In a vacuum it is worth 299 792 458 meters per second.

Just the speed of light in vacuum, according to the special theory of relativity, is a universal physical constant independent of reference system that we decide to adopt. It would therefore be the maximum speed with which any information is able to move in the universe, combining the classical physical quantities of space and time in the single entity of space-time and representing the conversion factor in the famous mass-energy equivalence equation.

If we turn to the theory of general relativity, the light speed becomes that predicted for gravitational waves.

Constant or not, and then we'll see why to insinuate this doubt in readers, is since October 21, 1983 that it has been established that the value of the speed of light in vacuum is an exact value, without error, and fundamental for physics, and not only. Precisely starting from this constant "c" in fact, the length of the meter is also defined in the International System.

Speed ​​of light: history

Einstein is certainly not the first man who has begun to investigate this magnitude, many before him have done so, developing rather "creative" theories or at least that appear to us today. In fact, some have in the past believed that light travels at an infinite speed. We had to wait Galileo Galilei to hear voices contrary to this theory, after him many others became convinced of his thesis and continued in this sense, helping science to reach the conclusions of which today we are certain, or almost.

After many centuries and many theories, years and years of calculations, it has come to be said that this magnitude is the maximum speed that can be reached in nature. It seems in fact, to date, that nothing and no one would be able to exceed the speed of light.

Speed ​​of light: Einstein

This fixed point is the one on which the theory of Einstein's relativity. Still up to a certain point, we will in fact see that there are some scholars who are questioning it. But let us return first to the theory of relativity of Albert Einstein to better understand its contents and its importance for humanity.

Einstein was able to argue that the speed of light was not only not infinite but that it was even possible to attribute a precise value to it, to be considered constant. We have already mentioned it but, being a non-trivial number to remember, let's repeat it: 299.792.458 meters per second.

It is clear that, when compared with the speeds we have to deal with every day, it is a very high speed. Nobody and nothing are able to overcome it in any way, according to Einstein, for the following reason. According to the theory of relativity, when an object increases its speed, it also increases its mass.

What does this entail? That every time an object accelerates, it also becomes heavier so it takes more energy to move it further. If so, then it is not possible for an object to reach infinite speed. In fact, there comes a time when the increase in speed it would begin to require an exaggerated amount of energy, so large that it cannot be found in the universe. All that remains is to accept the fact that the speed of light is constant and limited.

Speed ​​of light: research

Not to be mischievous, in science it is normal to verify and even disprove the theories developed by fellow predecessors and this is exactly what two physicists did when publishing a study in which it speaks of speed not constant, for light.

The two protagonists of this hypothetical revolutionary discovery are Magueijo and Afshordi. In the journal Physical Review D they made their conclusions appear that go against those reached by Einstein. These physicists argue that the speed of light was much higher in the primordial phases of the Universe and that, in reality, it has diminished with the passage of time.

We cannot say that we have proofs of all this in our hands, but research is still underway to prove this new thesis, by measuring the spectral index. What if the speed of light is really not constant? It would be a great revolution, and not just in the world of physics. Our whole universe and all theories about its creation should be changed from top to bottom. New theories, new questions, new frontiers for research would be found.

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Video: The Physics and Philosophy of Time - with Carlo Rovelli (July 2022).


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