Image possible evolution

The Evolution of the Universe

To understand the possible evolution of the Universe, we must refer back to the figure, beginning with the first circle at the top left. The circle represents a sphere and on its surface, there are two big dots. The surface of the sphere represents the Universe, while the dots are two galaxies.

The galaxies are subject to two forces, which have clashed since the birth of the Universe. One of these is the gravitational pull exercised by the galaxies, which attracts them mutually and, therefore, tends to make the Universe collapse on itself, and the second is the push caused by the Big Bang expansion. Which of the two forces will win is difficult to say.

The 3 circles on the top of the figure, going from left to right, describe the case in which the pushing pressure will win and therefore the case in which the Universe will keep its expansion forever.

The 3 circles on the bottom of the figure, always from left to right, represent instead the case in which the gravitational pull will win: there will be a time in which the expansion of the Universe will slow down until it will stop and afterwards it will begin to contract itself under the action of its own gravitational force.

What we have tried to describe here, in a very simply way, is the field of research of that branch of Astrophysics which studies the formation and evolution of Universe, that is Cosmology. We are making constant progress and we are gaining an ever more complete and precise picture of this, even if we continue to find new questions to adress. Indeed, the matter which emits radiation, that is the matter we can detect and therefore study, is only a very little part of the whole matter which constitutes the Universe. There is a lot of unknown material that is called Dark Matter: we argue from observations that it has to exist but, at the moment, we can’t see (detect) it.

According to even more recent studies, there is also Dark Energy which, it si supposed, played a fundamental role in the evolution of Universe: it is a force whose nature is, at the moment, little known and which could be responsible for the accelerated expansion of the Universe.

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