The virtual clock of the cosmos’ history strikes its last hours. Nothing of what is around us will survive the inevitable end: stars, planets, quasars and pulsars, galaxies and nebulae, even the mysterious black holes and the physical phenomena that have been only imagined so far, such as the wormholes. The universe is dying, or better, it is slowly and gradually extinguishing. This is what demonstrates a study carried out with the aid of innovative technologies by Simon Driver’s team, University of Western Australia, presented on the occasion of the last meeting of the International Astronomical Union, that took place in Honolulu, Hawaii.
This is the Gama project (Galaxy and Mass Assembly Survey) that has put together a huge amount of data collected for years from space- and ground-based telescopes. It has demonstrated, by analysing light samples of more than 200 thousand galaxies, that the energy produced by the cosmos today is about half of that emitted 2 billion years ago. Actually, we found out at the end of the ’90’s that the universe is slowly disappearing, but the new work shows that this is happening through all the wavelengths of light, from ultraviolet to infra-red. Using an apt metaphor, Driver has described everything around us as an old gentleman who is lying with a blanket on a sofa, waiting for the end to come.
According to Massimo Della Valle, director of the Capodimonte Observatory of the National Institute for Astrophysics (INAF), the research carried out by the Australian team is the result of a “herculean effort” because it required the measurement of energy emitted in the “last 2 billion years by a sample of 200 thousand galaxies” contained in a single section of the universe. A great result obtained by combining data provided by space telescopes such as European Space Agency (ESA)’s Herschel, Nasa’s Wise, and those of the European Observatory Southern (Eso) it the Chilean Andes. This way, he added, “the researchers have been able to measure the decrease rate of the radiation density on a broad spectrum; basically, a confirmation of the fact that the universe is extinguishing and of how it happens”.
What we still have to understand is how death will happen. On this point, the physicists continue to be at odds, because we do not know yet many of the laws that govern us. The most inflationary theories are the following two. The first one, that of the “Big Freeze”, argues that the cosmos, generated by the Big Bang will continue to expand indefinitely until all of the energy produced at the beginning of time will be finished, turning thus, everything into an immense black and frozen moor. The second one, that of the “Big Crunch”, imagines space as a kind of rubber band that, after it will have reached the maximum point of tension, will return precisely to the point where everything began. The gravity force, will gradually re-aggregate raw material into one single infinitely small and dense point. Similar, but more extreme than the Big Freeze theory is the one of the Big Rip, according to which infinite expansion will culminate in a return to a particle state of the universe. Essentially, when the forces that hold the celestial bodies together cease to operate, will begin a process of disintegration into progressively smaller pieces. Supporters of the Big Rip argue that at the end of time, in space there will be only photons, leptons and, perhaps, protons. There are also those who imagine a multiverse, i.e. the existence of multiple universes. But with this theory we move into the field of a suggestive hypothesis that is not scientifically provable yet.
Translated by Ecaterina Severin