Light faster, in the early universe? Original article by Alessandro Brizzi.







Light faster, in the early universe? Original article by Alessandro Brizzi.

The spectral index, a measurable parameter of the cosmic background radiation, could show that the speed of light had a different value in the early universe.

This was stated by the latest development of a twenty-year theory that questions the constancy of the fundamental constants of nature and challenges the inflationary universe model, formulated to make uniformity account the average density of the observable universe. The constants of nature are really constant? It is a question that has taken away the sleep in more than a theoretical physicist, because if you were to vary certain parameters in space and time, even at a great distance from us, the description that the physical laws of the universe they would be decidedly different.

This is the case for example of the speed of light, according to Einstein’s theory of special relativity, does not change with the reference system used to measure it, as it should be if they continued to enforce the laws of Galilean relativity. In other words, the speed of light is an absolute constant, in addition to being a speed limit, can not be overcome either by particles with mass nor from information. It is a postulate that served to build other important theories such as general relativity of Einstein, a gravitational theory which explains the large-scale structure of the cosmos, the universe’s evolution from a catastrophic initial explosion, the Big Bang, and the existence of extreme objects like the blacks holes.

The predictions of the theory of general relativity have been confirmed countless times; yet there are researchers who now raise some doubts on its foundations: and if in the early universe, a few seconds after the Big Bang, things had been different? At the end of the nineties, some astrophysicists hypothesized that for example the speed of light may have been much higher just after the big bang.

Now the same researchers have formulated a prediction experimentally verifiable, which should allow to understand whether it is a plausible hypothesis. The structures in the Universe, such as galaxies, they are all formed from fluctuations in the early universe, that is, density differences from region to region.

A recording of these primordial fluctuations is imprinted in the cosmic microwave background, the “fossil” radiation that is all that remains of the first propagated light in the universe. So if the speed of light was changed in the early universe, the density fluctuations would be affected. And a track it would have been in a physical parameter associated with the cosmic background radiation: the spectral index, which in this case should be equal to 0.96478, compared with a currently unknown value of 0.968, with a certain margin of error. The theory we have proposed for the first time in the nineties has now reached full maturity, because it produced a prediction experimentally testable: if the observations in the near future were to confirm this value, you could get to a modification of Einstein’s theory of gravitation, and it would mean that the laws of the nature in the past could not be the same as today. If the idea of the authors had occurred, the expense could also be another very popular theory: the inflationary universe. The latter provides that the universe, in an early stage of its existence, it experienced an extremely rapid expansion phase, called inflation, which allows cosmologists to solve the “horizon problem”. In essence, the universe as we observe it in our time has a relatively uniform density, and this is possible only if in a primordial phase all the regions of the universe have been able to influence each other. To do this, or the universe at a certain stage was very small, as expected by the inflationary theory, and began to expand only after the uniformity of the mass was established, or the speed of light was very high, so as to allow the communication between the different parts of the universe even when it was in a phase of expansion.

Light faster, in the early universe? Original article by Alessandro Brizzi.

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