by Acad. Anatoly CHEREPASHCHUK, Director of the State Institute of Astronomy named after P. Sternberg, Lomonosov Moscow State University

Contemporary cosmology is focused on a mysterious phenomenon called "dark matter". The only thing we know is that it is a matter neither radiating nor absorbing light. Moreover, astronomers and many physicists believe in existence of "wormholes", the discovery of which enable people to travel in time and space. All this is very intriguing and gives rise to numerous questions. The well-known scientist Academician Anatoly Cherepashchuk, Director of the State Institute of Astronomy named after P. Sternberg, MSU, clarified some of these questions to Margarita Timofeyeva, journalist.

-- Anatoly Mikhailovich, could you explain, what is "dark matter"? Have scientists managed to find a key to this mystery?

-- To start with, I must say that after the Big Bang, all matter in the Universe divided into a number of components. Cosmological data demonstrate that only 4 percent of its mass is made up of ordinary matter, i.e. all of us and everything around us, everything made of visible particles and able to radiate light due to electromagnetic interaction. Thus, we consist of baryon matter that includes atomic nuclei made of widely known protons and neutrons. They were studied long ago and classified in Mendeleev's Table. About 0.5 percent of the mass falls on neutrino. They are particles without charge emitted by the Sun, and their studies make it possible to get information on all processes running in the center of our luminary. The remaining 96 percent of the Universe's mass fall on the so-called "black sec-

tor", prevailing in the Universe, with two fractions, where 23 percent is occupied by "dark matter" and 73 percent by "dark energy". Like ordinary matter, "dark matter" exists in all galaxies and clusters of galaxies; it can thicken and twist under gravity. Indeed, it neither radiates nor absorbs anything, as it does not participate in the electromagnetic interaction. Astronomers discover it due to gravitation produced by it. Perhaps, we deal here with weakly interacting elementary particles weighing 1,000 times more than protons unevenly spread in space.

In contrast to "dark matter", "dark energy" is spread in space evenly and has exceptional properties. It is a certain field of unknown physical nature. The only thing we know is that it has negative pressure which leads to gravitational repulsion and accelerated expansion of the Universe. The nature of "dark energy" is the main scientific mystery of the 21st century. A key to

this mystery will irreversibly change our vision of the world.

In late November 2009, the Large Hadron Collider (LHC)* was successfully launched at the European Center for Nuclear Research (CERN, Switzerland). Unique research conditions will enable scientists to watch rare physical processes and unconventional peculiarities of already known particles and reactions, as well as to discover absolutely new phenomena. Different experiments and research works implemented on this Supercollider will help us to unravel the mystery of "dark matter", which undoubtedly will make mankind reconsider the history of the Universe.

-- Is Russia participating in these experiments?

-- Yes, it is, but, unfortunately, we are not prime sponsors, so we are engaged only in designing of different devices and appliances. For example, to become a member of the South-European Observatory uniting 40 countries, Russia must contribute 120 mln Euro;

* See: L. Smirnova, "The Future of Marine Nuclear Power", Science in Russia, No. 5, 2010.--Ed.

only after this we'll have access to telescopes located in Chili, where perfect environmental conditions enable scientists to carry out astronomical studies. Up to now our government did not make any decision on this issue. It is really disappointing: they have already started developing the largest telescope on the Earth with a 42 m diameter. Scientists are putting hopes on this telescope, as they believe it will help answer all fundamental and exciting questions of present-day physics and delve deeper into the mysteries of the Universe. By the way, the largest existing telescopes are 10 m in diameter; Russian telescopes are even smaller--not more than 6 m. We hope this new telescope will become a benchmark to confirm or deny some of the proposed theories and hypotheses.

-- Anatoly Mikhailovich, can you tell anything new about "black holes"? Have scientists found any evidence of their existence ?

-- At the moment, there is no final evidence of their existence, but scientists have discovered thousands of compact objects very similar to "black holes". But this is only for the moment. As an astronomer, I believe

mankind is on the verge of discovery of this unique phenomenon. This will be a breakthrough in our understanding of space and time, as space and time can change places in "black holes". "Black holes" come into being in the course of contraction of central parts of massive stars with nuclei weighing more than three Suns. As a result of contraction, there forms a certain very small object of an enormous mass characterized by unique properties: it has "a horizon of events", where time stops for an observer, and all processes run with decelaration. But there is no observed surface there. We can get into a "black hole" on a space shuttle, but due to strong gravity we'll never return or send a signal. A man inside "black hole" will move towards the so-called "singularity" and finally die; from the observer's point of view, the man will be moving towards the horizon of events for an endlessly long time. For example, a spaceman in the space shuttle can get into the "black hole", and it will seem to us as if it has stopped near the horizon of events. A paradox!

As I have already said, there have been discovered thousands of objects looking like "black holes", and the only thing we must prove is that they have no observed surface, only the horizon of events.

-- How would you assess the probability of our planet to be taken up by such "black hole"?

-- "Black holes" are located at distances comparable with mileages to stars, i.e. very far away. Their effect is similar to other stars of the Galaxy, it is negligibly small, and we do not feel it. Gravitation field of black holes located at big distances is indistinguishable from that of stars. You can feel its effect only if you approach them closer.

-- Today there are held many discussions on the existence of the so-called "wormholes". Is it true they could help create a "time machine"? What is the difference between a "black hole " and a "wormhole"?

-- Yes, it is true. Einstein's general theory of relativity that describes the gravitation field does not exclude existence of such objects. There exists a matter they could be formed of--recently discovered "dark energy". The only missing component is evidence of stability of "wormholes". As soon as scientists prove this theory, the "time machine" will become true.

Unlike a "black hole", a "wormhole" has no singularity in its center. It has no horizon of events, which makes it possible to get into the hole and get back. Negative pressure forms so-called tunnels in time and space, and you can get through them to different Universes not interconnected causally.

Today astronomers and an increasing number of physicists say such "holes" may exist. These objects are very exotic, they heat up imagination, and many people hope scientists are very close to discover them. But here we come into antagonism with a principle of causality when you can change the future from the past. Besides, there is another thing called "the grandfather's paradox". Imagine, you discovered a "worm-hole", entered it and found yourself in the past. There you meet your grandfather whom you can kill. A question arises: how could you be born then? Is not it in contradiction with the classical principle of causality? Scientists are trying to solve this complex problem.

-- When man is in the "hole ", what will happen at that moment in the present?

-- Inside and outside of "wormholes" time goes in different ways.

-- Perhaps, we'll be able to get in touch with extraterrestrial civilizations through "wormholes"? Anatoly Mikhailovich, do you think they exist?

-- Yes, of course. I'm sure one day, traveling in time and space, we'll meet them. Search for extraterrestrial civilizations is the main scientific task for the next twenty years. We are really taken by an idea of getting acquainted with extraterrestrial strangers. A special radiotelescope was designed in the USA that will rake

around the sky for signals of other civilizations. Many millions of dollars are spent to develop necessary instrumentation. By the moment, over 500 planets orbiting around other stars have been discovered; it seems quite possible that almost each star has its own planetary system. And this means there might exist planets similar to the Earth.

-- In other words, if it is necessary, Earth men could move to another planet?

-- You know, scientists have already some speculations in this respect. For example, Jupiter has a satellite where water covered with ice has been discovered and it cannot be ruled out that we would move there, if necessary. According to the estimates of astronomers, in 4.5 bln years the Sun's radius will increase 100 times. The star is constantly expanding. In due course the Earth will start sliding over its atmosphere and finally will make part of the star. All flesh on the Earth will die. Jupiter is located much far away from the Sun, so it can be assumed that we might settle on the satellites of Jupiter or Saturn. In this respect mankind should be more persistent and try to find ways enabling us to populate another planet fit for normal existence.

-- Does this mean that in the next 4.5 bln years we can live in safety and be indifferent to the danger coming from the Sun ?

-Astronomers have calculated evolution of the Sun. We know the nature of many stars; we know their internal structure and understand mechanisms of evolution. The Sun is a stationary star. Its radius will increase gradually but there will be no explosion, so we should not be afraid of it. There are many variable stars in our Galaxy. But astronomers know the mass, radius and temperature of the Sun. Hence, we can make a conclusion that our celestial body is a stable star that will ensure our being for billions of years.

- Anatoly Mikhailovich, what do you think about comet and asteroid hazards ? Do they exist? If yes, can we prevent them?

-This problem is pressing for many scientists worldwide. The point is that we have already developed efficient methods to exert influence on asteroids and comets*. A special RAS Committee for studies of near-Earth objects, asteroids and comets has been established and is headed by Boris Shustov, RAS Corresponding Member. If one day we localize such an object, we'll be able to oppose it. For example, we will manage to exert influence on it: to launch a space shuttle as a gravitational tractor to deflect for several centimeters in the orbit. If necessary, we'll blow it up with nuclear charge, though we must be very careful in this case. Anyway, we have efficient technological opportunities to influence these objects; that is why mankind is focused on this topic now. As I have already mentioned, scientists all over the world are engaged in designing of large telescopes that will enable us to study near-Earth space more thoroughly.

- How often do these objects "visit" the Earth? Which one was the most interesting?

- Ten years ago there were discovered meteorites coming from Mars. Scientists found them, sawed them and revealed traces of fossilized microorganisms. It was a sensation: as if we discovered life in the form of microbes on the other planet. But, unfortunately, further studies revealed some problems of this interpretation. Those traces could well be crystals of a certain matter looking like bacteria. But it was one of the most intriguing findings coming from outer space. As you know, an enormous quantity of frozen water was discovered on Mars**. Probably there exists life in the form of microorganisms under soil. It is true: at the equator of the Red Planet temperature rises up to 10ºC in summer. At the same time terrestrial microbial flora in the depths of our planet exceeds the volume of life on the surface and in the atmosphere. So, why cannot there be a similar life on Mars? After discovery of these "suspect" microorganisms in Martian meteorites, the American government launched a Red Planet research program aimed to find traces of life on this planet.

* See: A. Litvak et al., "Cosmic Wanderers". Science in Russia, No. 2, 2003.--Ed.

** See: 1. Mitrofanov, "Unlocking Martian Enigmas", Science in Russia, No. 6, 2002: M. Litvak, I. Mitrofanov, "Martian Seasons", Science in Russia, No. 4, 2004.--Ed.

- Are there any lunar research programs being implemented at the moment? Is it true that we are more and more close to the construction of lunar bases and observatories?

- Exploration and development of the Moon is one of the most important tasks for astronomers; it will give a key for understanding of the origin of the Moon-Earth system. I hope Russia will focus its attention on this topic. At present scientists discovered water on the Moon in the so-called "cold traps"*. There are craters in its polar areas never warmed up by the Sun. Shadows produced by tops of the craters exist eternally, and the temperature is very low there. When comets fall, they evaporate and frost forms a sediment in cold traps. For many billions of years a lot of water could accumulate there.

Consequently, a potential scenario of development of our closest neighbor can be elaborated with regard to this circumstance: water is indispensable for life on a future lunar base, as oxygen released from water will provide air atmosphere at the station and hydrogen will be efficiently used as a fuel for space shuttles and vehicles. Establishment of a polar space observatory on the Moon will be of great help for further construction of astronomical, heliophysical and meteorological stations. Hence we hope that asteroid threat control systems, monitoring and early warning of terrestrial catastrophes, studies of far outer space, etc. will be soon set up there.

- What are the main tasks of astronomy as a science for today ?

- From the philosophical viewpoint, our top priority task is search for life beyond Earth. Contemporary astronomy has all instruments to manage this task. As a part of an extraterrestrial life search program, we should also explore planets of the Solar System. Another task is to understand the nature of "dark energy" and gravitational repulsion. Even now we can say that existence of "dark energy" testifies to a new stratum of physical phenomena taking place at superlong distances. There are still undiscovered types of matter-they are sought for on the Large Hadron Collider. Finally, there exist "black" and "wormholes", and, consequently, we have to solve the causality problem. All these tasks are a great challenge to fundamental science.

There are also applied tasks. The one we are dealing with is the GLONASS navigation system**. It is essential for successful achievement of many national goals, First of all, in the field of national security and defense potential. Among other priorities are tasks set before other fundamental sciences, navigation support of land, marine, air and space means and objects, distribution of uniform geodetic systems and time scales, preliminary mapping and survey works on land and sea, demarcation of boundaries. The GLONASS navigation system requires very exact measuring of time and irregularities of the rotation of the Earth. Even insignificant deviation of the axis will be enough to deteriorate navigation accuracy. This must be taken into account. And the main task is mastery of the Moon as a storeroom of natural resources, a unique place for space observatories, a launching pad to get to Mars and other planets of the Solar System.

Illustrations supplied by the author

* See: E. Galimov, "'Luna-Helium-3' Project", Science in Russia, No. 6, 2006; Yu. Avsyuk, "Focus on Lunar Studies", Science in Russia, No. 6, 2006.--Ed.

** See: Yu. Nosenko et al., "G LONASS: Today and Tomorrow", Science in Russia, No. 5. 2008.--Ed.