Matter as we know, the one made up of protons, neutrons and electrons, is only a small part of the total matter and energy in the universe. 95% of the universe is composed apparently of dark matter and dark energy. A new theory is that dark matter might turn in time intodark energy. This fact would explain a series of measurements that have to do with the rate of formation of mega-structures in the universe. However, there are many doubts about this theory.
Currently, most scientists are convinced that the universe is dominated by the dark matter and dark energy. Dark matter would explain a number of facts that have to do with how the stars move in galaxies or even the galaxies in the galaxy mega-groups, while the dark energy would explain why the expansion of the universe is accelerating.
While the dark matter have gravitational effects like normal matter – the one we know and study in our laboratories – the dark energy is a big mystery: acts like an anti-gravity force – a somewhat strange energy, which we know very little about. Dark matter may be composed of particles that we have not discovered yet, but we search in various experiments at accelerators or underground laboratories. But the dark energy gives us headache: is there a vacuum energy, quantum effects related? Or something else?
Recently, the observations using Planck space telescope have complicated further the situation: Planck measured an abnormal rate of formation of mega-structures in the Universe. From observations made on the cosmic background radiation (microwave) was inferred that the rate of formation of these mega-structures was slowed in the last 8 billion years of life of the Universe (recall that the universe, according to the Big Bang theory would be born about 13.8 billion years ago).
What caused the slowdown in the rate of formation of these structures in the Universe? Researchers Valentina Salvatelli, Najla Said and Alessandro Melchiorri of the University “La Sapienza” in Rome, and Marco Bruni and David Wands of the University of Portsmouth, UK, had a very interesting idea: what if dark matter is transformed into dark energy? They created a model in which this transformation was authorized and thus they were able to explain why mega-structures in the universe are formed more slowly than in the past. The disappearance of dark matter would be to blame! The results of this study were published in Physical Review Letters.
If indeed this is so – then the fate of our Universe is not too happy: when all the dark matter will turn into dark energy will no longer be forming structures! It will be a cold universe, unwelcoming and with no matter! When will happen this cosmic tragedy? If we are to believe this study, the process would take about 100 billion years.
Not all scientists, however, agree with this idea. There are a number of alternative ideas that explain the current situation. Some of these ideas have to do with changes to the theory of gravitational interaction. Others claim that the dark matter is composed of so-called sterile neutrinos, and in this case would explain the mystery of decreasing rate of structures form in the Universe. At present we do not know which of these theories could be applicable; the answer may be different from anything we imagine today!
But what is certain is that we need experimental observations – such as Astronomy and Astrophysics and in studying particles laboratories on Earth – of greater precision, able to guide us to the right answer. In the coming years we will probably unravel the mystery of the dark matter, which will help us to better understand what might be the origin of ther dark energy, energy that is one of the biggest mysteries in today physics.