鈥� ...The accelerated expansion of the Universe discovered during the last decade may be interpreted in two ways: either by the presence of a new state of the matter called 鈥渄ark energy鈥� or by the variation of gravitational interaction at large distances.
According to the conventional theory of gravitational interaction, all bodies of a finite dimension are attracted to one another. But bodies of an infinite dimension are repelled from one another. It would be interesting to note that according to Newton鈥檚 old theory gravitational repulsion is never possible or the Universe wouldn鈥檛 be able to expand and life would be impossible. The starting impetus that has led to the Universe expansion (the so-called cosmological inflation) may be only in Einstein鈥檚 theory.&苍产蝉辫;鈥�
Prof. Alexandre Dolgov is engaged in some lines of investigation in cosmology, astrophysics and physics of elementary particles. At NSU he has been at the head of the Laboratory of Cosmology of Elementary particles since 2011. It was created due to the megagrant given by the government of the Russian Federation. But this year the financing will end.
鈭� Professor Dolgov, do you think you the state will give you support again?
鈭� Nobody knows. But I hope it will. Large sums of money have been invested already, expensive equipment has been bought. We are doing serious research and I think it will continue. Otherwise, we鈥檒l have to look for other ways of proceeding with the research. One of the problems of the Laboratory to solve is to make a group at NSU that will do research in cosmology and astrophysics. But it is impossible to do it during two years. In September an inspector who is going to evaluate our work of this period of time is arriving.
鈭� What have you done?
鈭� First of all, a decisive step in constructing a detector has been made. We鈥檝e passed on to a working device from a small model.
In the theoretical part of the investigation we鈥檙e dealing with two branches of science: cosmology and astrophysics. In particular, the research workers have discovered a new technique for the determination of cosmologic distances. It is very important for studying the properties of dark energy. The accelerated expansion was discovered when it became known that distant supernova of 1a type appeared to be dimmer than it used to be considered in cosmology. Thus they are farther and expand quicker than it was expected. It is important to know at what distance the supernova were. The traditional techniques of distances determination are multistep and may have systematic errors. Our theorists have found a new faultless technique. They suggest supernova of another type that throw down their coats repeatedly should be observed. Then it would be possible to determine the distance from them seeing the dimensions of the coats. This is the right technique of determining the expansion rate of the Universe.
Besides, we try to understand what is a carrier (or carriers) of the dark matter when we study the consequences of this or that form.
An important problem connected to dark energy is the problem of vacuum energy that, according to the theoretical conclusions, exceeds the permitted value to 50 or even 100 orders. In this case the life in the Universe wouldn鈥檛 be possible. The problem of vacuum energy is one of the most significant in physics, and to solve it the basic principles of the theory will have to be changed. But the problem can鈥檛 be solved yet.
It should be said that according to the results of the theoretical and experimental work of the Laboratory, about 20 scientific works were published and reports were read at many international conferences.
鈭� Were you able to 鈥渇eel鈥� the dark matter with the help of the detector?
鈭� It is impossible to do it with the detector prototype developed in the laboratory. Firstly, a detector of a bigger volume is needed. Now we have got a working model. Secondly, one should work in a place protected against solar radiation. Italian researchers do so under the supervision of Rita Bernabea. Her laboratory is in Central Italy in a cave under Gran Sasso mountain. The experiments they perform there are unique as the cave is under the mountain. They see a signal that can be interpreted as the registration of the dark matter. The detector is constantly counting something and they see that the signal force changes like the seasons. And it is natural because the Earth either meets the particles of the dark matter or escapes from them. The chance of their interaction depends on the speed. It is an interesting fact but in other similar experiments the effect isn鈥檛 seen yet. The absence of the signal may be accounted for the difference of experimental conditions and sensitivity of the detectors.
Besides, a wonderful highway leads to Gran Sasso. There the allowed speed is 130 km per hour but Italians don鈥檛 like restrictions.
Our detector can also be used but for lighter particles.
鈭� Why should the dark matter be looked for? What are the prospects of finding it?
鈭� What will the national economy get? (Prof.Dolgov laughs) . Nobody knows. Once when Faraday was showing his experiments with electricity, he was asked,鈥漌hat good will it do?鈥� He answered,鈥漎ou鈥檒l get taxes to pay鈥�. I don鈥檛 know if we鈥檒l have to pay taxes. Dramatic discoveries always bring benefits. Pauly, to whom we are indebted for the discovery of neutrino, said,鈥滻 did an awful thing. I thought there were particles that nobody would ever see.鈥滲ut now neutrino is seen. With it the Earth is going to be sounded, atomic power stations are going to be diagnosed etc. It is difficult to predict how the problem of the dark matter will be solved, perhaps, physics will have to be revised.
鈭� Were any discoveries announced at the last conference 鈥淒ark matter, dark energy and their detection鈥�?
鈭� No discoveries were announced. Discoveries are seldom made. It was a good conference. There were many participants.
鈭� What lays in store for the Laboratory of Cosmology and Elementary Particles?
鈭� I hope the term of financing will be prolonged but it is for the Ministry to decide. We try to satisfy all the demands and no censure can be roused. Some leading research workers from Moscow arrive at the University to deliver lectures because, unfortunately, cosmology and astrophysics are not developed here. We hope to make a group of young research workers who will live and work in Akademgorodok.
