by. B. BOLOTOVSKY, D. Sc. (Physics and Mathematics)

Among fellow scientists Dr. Andrey Sakharov is remembered as the "father" of the Soviet H-bomb. And this is what he was, having dedicated to the project close upon twenty years of his life. His main sphere of interest, however, was not the applied side of it ail, but the associated basic problems of physics.
Andrey Sakharov was a truly outstanding man of science in his own right, although the exact scale of his achievements is fully understood and appreciated only by experts.


It was in 1948 that the young physicist Sakharov was appointed to the Soviet H-bomb project surrounded by an impenetrable veil of secrecy. But even before he left for the project site, he, as many of his associates, was already doing some top-secret research. As a matter of fact, most, if not all research conducted in this country at that time was classified in line with a general obsession with secrecy.
As for the basic physical facts of the matter, when two light nuclei "merge" or fuse into one, a certain amount of energy is released. But for the fusion to take place the nuclei must come very close to one another, and this is very hard to achieve since both of them happen to have a positive charge and repulse each other. To over- come this mutual repulsion, which continues to grow as the nuclei approach each other, one can try and heat the gas consisting of such light nuclei to a high temperature. Then the kinetic energy of the nuclei will be high enough for them to overcome mutual repulsion so that the dis- tance between them would be small enough to permit what physicists call hot fusion to take place.
As for Sakharov, he hit upon another way of achieving such fusion which does not require the heating of gas. Suppose a negatively charged particle enters the gap between the two positively charged nuclei which repulse one another. Then the two nuclei become attracted by this particle so that a molecule can be formed of the three. In this new molecule the distance between the two light nuclei will depend on the mass of the nega- tive particle - the greater this mass the closer the distance. Now, what if this "uniting" particle is a mu-meson, an elementary particle twiee as heavy as an electron? It can bring the nuclei in the molecule so close to one another that they can fuse and energy is released. Acting as a ^ catalyst, the mu-meson promotes the formation of new molecules. This work, pioneered by Dr. Sakharov, opened up a whole new field of research which is rapidly developing today.
In an H-bomb explosion light hydrogen atoms fuse into heavier atoms of helium. This fusion sustains the energy of the blast which scatters the light nuclei so that not all of them have time to enter into the aforesaid reaction, or "burn down." The more hydrogen "burns down" in this way, the greater is the power of the blast. Dr. Sakharov resolved this problem by putting hydro- gen into a "vessel" of a heavy element, in a ther- monuclear blast, of course, any such "vessel" would be evaporated within fractions of a second. But as Sakharov had figured out, this vapor con- sisting of the heavy element atoms exerts a strong enough pressure upon the hydrogen in its midst for it to "burn out" to the required extent. The mechanism suggested by Sakharov was so unorthodox, that after the initial dismay, the enraptured physicists called it "sakharization."
It was in the late Forties and early Fifties that Dr. Sakharov, then working on the H-bomb pro- ject together with lgor Tamm, put forward the idea of peaceful uses of thermonuclear energy. in the bomb a vast amount of this energy is released instantly. For peaceful uses this energy release should be slow and kept under control. These basic ideas were formulated in the works of the two Soviet physicists, and at about the same time similar concepts were advanced both in the United States and Great Britain. All this work, however, was absolutely top-secret, but in 1956 another top Soviet nuclear scientist, lgor Kurchatov, shed light on Soviet research into controlled nuclear fusion in a report made at Harwell in Britain. That event marked the begin- ning of international cooperation in this field. And although the problem is still far from being resolved, experts remain optimistic and say that in the first quarter of the next century mankind will have at its disposal a safe, inexhaustible and environmentally pure source of energy.
Among the new ideas "generated" by Sakharov in those years was a new way of obtaining super-strong magnetic fields.
As is known, any variations of a magnetic field encircled by a loop generates electrical currents in this loop. These currents are such that they try to "prevent" magnetic field variations. Experts say that amagnetic field inside a highly conducting loop is "frozen." Now if we somehow constrict the loop, the magnetic field inside will likewise be constricted and will grow (the strength of the field multiplied by the area of the loop as a physical constant), leaving put forward this general idea, Dr. Sakharov also suggested its practical applica- tions. He wrote, for example, of a hollow metal cylinder placed within a coil through which a cur- rent flows. The cylinder embraces a "bunch" of magnetic lines of force of an "initial field" generat- ed by the coil. Outside the cylinder we place an explosive charge which is then detonated. The blast compressed the cylinder and the "bunch" of magnetic lines of force inside. The intensity and strength of the magnetic field soar.
A strong magnetic field can be used, for exam- ple, for studies and processing of materials, for the conservation of large amounts of energy with- in a small volume and for charged particles acceleration. This research was pursued with Sakharov's active participation during his work on the H-project and after he joined the Institute of Physics of the USSR Academy of Sciences (bet- ter known among experts as FIAN). The record magnetic field obtained by this method measured 25 million Gauss, a value that cannot be reached by any other known methods.


As the work on the H-bomb was moving towards fruition, Dr. Sakharov began to devote more of his time to his favorite theoretic physics. He focused his gaze on phenomena just as impressive as the bomb. As for the H-bomb, its blast releases vast amounts of energy generated by forces contained in truly microscopic space. Dr. Sakharov turned his attention to a space of entirely different dimensions. In our expanding Universe stars and galaxies are "flying away" from a hypothetical center and the further is a space object from the center the greater is its velocity. This picture leads us to the assumption that originally the whole matter of the Universe was compressed within a very small volume, much smaller than the size of an atom. The den- sity of the energy it contained much have been truly staggering. This original "core" was like a boiling pot in which elementary particles were constantly born, absorbed, disintegrating and undergoing all sorts of transformations. After the bang, and as the initial matter began to scatter, its temperature and density continued to drop, the interaction among the particles weakened, leading to the formation of atomic nuclei, stars, systems of planets and galaxies, finally produc- ing the Universe as we see it today. If this hypothesis is generally correct, then we would be right to assume that the properties of the bound- less Universe are governed by the laws that gov- erned the "behavior" of matter within the initial tiny "core." Dr. Sakharov turned his attention to problems betraying a cause-and-effect connec- tion between things infinitely great and infinitely small.
In his work published in 1967 he tried to answer the question of how the Universe has reached its present stage. In the part of the Universe which we know there are heavy ele- mentary particles called protons, but no corre- sponding anti-protons. But according to theory a proton is always born in pair with an anti-proton. And the two cease to exist also in pairs with the proton annihilating its opposite. This being so, there should be just as many anti-protons in our Universe as there are protons. Alas, this is not really so. in his publication Dr. Sakharov offered a brilliant explanation of this puzzling assymetry. If, as was generally assumed, a proton can only be annihilated by an anti-proton, protons would have to exist forever in a world devoid of anti-pro- tons. In other words, the proton was regarded as a stable particle. In his work in 1967 Dr. Sakharov suggested that this is not so. A proton is unstable and disintegrates into a mu-meson and two neutrinos. The anti-proton also disinte- grates, but in its own and "opposite" way. Anti- protons formed when the Universe was still young have all died down since, but protons linger on. If Dr. Sakharov's view is correct, it leaves no hope for an "anti-world," a world of antimatter, a mirror image of our own.
This work led to an important conclusion which could be ascertained experimentally. If proton is unstable - why not try and measure its lifetime? Such attempts have been made in many labora- tories around the world and Dr. Sakharov was looking forward to the results as long as he lived. On the other hand, it can very well be so that the lifetime of a proton is something very long, much longer than the time of these observations.
It is interesting to note that ten years after this publication, several physicists, including Prof. Abdus Salam and Prof. Stieven Weinberg, sug- gested a Great Unification Theory for the weak, strong and electromagnetic interactions of elementary particles. This theory regards from a common perspective phenomena of an apparently abso- lutely different nature. And it too suggests that the proton is an unstable particle.
Had the hypothesis about the instability of the proton been supported by experimental data when Dr. Andrey Sakharov was still alive, he would have certainly been awarded a Nobel Prize for physics in addition to his Nobel Peace Prize.
In physics he was in his "natural element," dis- cerning by intuition things which took others whole decades to grasp. This remarkable insight was his natural gift, like the gift of an artist, which defies any logical explanations.
Sakharov pioneered a method of obtaining magnetic fields of record strength. This method remains unsurpassed to this day.


Ever since he was a young man, Dr. Sakharov was noted for taking absolutely unorthodox views of commonly accepted things. His judgements and opinions puzzled even experts at first sight.
Here is just one, but fairly typical episode. When young Sakharov was taking his exam for the degree of Candidate of Science, the exami- nation board included three leading authorities in the field: lgor Tamm (later a member of the Academy), Sergey Rytov and Yevgeniy Feinberg (both later elected Corresponding Members of the Academy), lgor Tamm was puzzled by one of Sakharov's answers, and when members of the board were later discussing the results of the examination, he communicated his misgivings to Rytov and Feinberg. All said they failed to follow Sakharov's line of reasoning and decided that he did not deserve the top mark. Back at home that evening Tamm kept thinking about Sakharov's answer. Finally he grasped his point, which was absolutely correct. And just at that moment the telephone rang and Feinberg called to say they all had to appologize to Sakharov and correct the mark. And that was exactly what they did on the following day. I heard this story first from Academician Tamm and later from Prof. Feinberg. In 1967, Dr. Sakharov published the first in a series of works on the nature of gravitation. These publications offered a novel and most promising approach to gravitational forces.
Gravitation was always regarded as a basic natural phenomenon, more "basic" than many others. The G-constant is as "constant" as the charge of the electron or the velocity of light. History of science remembers outstanding natu- ral scientists and philosophers who tried to explain gravitation in terms of mechanics and later of electricity, or electrodynamics to be more exact. Following the failure of these attempts, gravitation was simply called together with all other and really fundamental forces, like the elec- tromagnetic ones, for example.
Our modern views on gravitation rest on the general relativity theory formulated by Einstein. According to this theory, the properties of space change in the vicinity of massive bodies, with the space being "bent" or "distorted," so that the shortest distance between two points is no longer a straight line, but a curve. One common illustra- tion of this is a ray of light which deviates from a straight path near the Sun.
Let us now take a copper strip and bend it slightly. When the pressure is off the strip becomes straight again. When we bend the strip we perform some work and the strip accumulates a certain amount of energy at the bend. This energy is later expended to restore the strip to its original shape.
And this is exactly how Dr. Sakharov explained the "bending" of space in the theory of relativity. The space "unbends" (and becomes Euclidean again), when these large bodies, or masses, are removed. Dr. Sakharov described this property of space (and time) as "metrFc elas- ticity". The greater is the "bending" of space, the greater energy is stored therein. Dr. Sakharov assumed that this energy, stored in distorted space, is the energy of the fields describing material particles. If one examines the energy of material fields in non-distorted space and then try and calculate this same value in distorted one and compare the two results, one can measure the energy expended on the distortion. This of course, is a very rough and general description of Dr. Sakharov's ides.
Within the general theory of relativity equa- tions describing the gravitational field are obtained with the help of a function postulated by Einstein and Gilbert (the action function). Using it one can obtain an equation describing the prop- erties of space and time. And it may be interest- ing to note at this point that the Einstein-Gilbert function was not calculated, but just postulated.
Having said all that, let us now set aside the relativity theory and consider in terms of the quantum theory a certain field describing parti- cles of a specific kind. An equation describing the quantum field can be obtained if we know the function of action of this field. This is different from the Einstein-Gilbert action, and quantum field equations are different from those of the general relativity theory.
Let us consider the action function for a quan- tum field in two cases - a straight and a distorted space. The difference between the two action functions describes the distortion of space. Dr. Sakharov demonstrated that under certain condi- tions this change of action for a quantum field is the same as the Einstein-Gilbert action in the general relativity theory. This leads to the same equations as in the general relativity theory, but now these are not postulated, but derived from the quantum field theory. And that means (if Dr. Sakharov's theory is right) that gravitation is not something basic and fundamental, but secondary and deriving from the quantum theory. Dr. Sakharov also obtained an expression describing the gravitational constant through such constants as the velocity of light, the Plank quantum con- stant and a certain minimal length. In this manner Dr. Sakharov obtained the general relativity equation from quantum field theory equations. Gravitation - this basic force of nature - has lost its status of a fundamental interaction. To my mind, Dr. Sakharov's works on this matter have not yet received the recognition they deserve.


This phrase applies to Dr. Sakharov the scien- tist and Dr. Sakharov the public figure. And when he saw what he saw, he made his views public. This gift of insight, to my mind, is the hallmark of the creative personality, and Dr. Sakharov was just that. He was among the first to alert the pub- lic to the grave menace from nuclear arms to all living beings on this planet. I was told that before each new H-bomb test, he would lock himself up in his room, calculating how many more human lives it would claim, including cases of cancer, leukemia and congenital deformities. These cal- culations, which often lasted for weeks, were done as professionally as everything else he did. His conclusions did a lot to change our ideas of radiation hazards.
People are usually afraid of heavy doses of radiation causing radiation sickness. In a high- altitude bomb test there are no any such immedi- ate casualties. But, as Dr. Sakharov pointed out, an H-bomb blast released a flood of neutrons into the atmosphere. These are captured by nitrogen
Had Sakharov's ideas on the instability of the proton received experimental proof in his lifetime, he could have been awarded a Nobel Prize for physics in addition to his Nobel Peace Prize.
nuclei, producing a radioactive isotope of carbon which has a life of about six thousand years. This radioactive isotope gets into the human body, food chains and water, affecting many succes- sive generations. According to Dr. Sakharov a bomb test of one megaton would claim more than 6 thousand human lives over a period of 8 thou- sand years. And there were atmospheric nuclear weapons tests of 100 megatons and more. All such tests were denounced by Dr. Sakharov as mass murder, and he pressed for a comprehen- sive test ban. His views were summed up in an article published in a collection of papers called "Soviet Scientists on Dangers of Nuclear Weapons Tests" published in Moscow in 1959. His protests, however, were dismissed as ill-con- sidered whims and were frowned upon by Nikita Khruschev. The then Soviet leadership was all in favor of keeping up the tests at any cost.
But the persistent anti-test campaign of Dr. Sakharov was not in vain and in 1963 the nuclear powers signed the test ban treaty in three media - water, air and on the ground, in the subsequent years the scientist continued to focus his atten- tion problems of radiation safety. After the Chernobyl catastrophe he suggested placing nuclear stations in underground tunnels. As for
Sakharov's remarkable intuition let him see things which remained hidden from others.
the increased costs, he pointed out that the cost of dealing with the aftermath of Chernobyl exceeded the building costs of a score of under- ground stations. Among the discouragingly few supporters of Dr. Sakharov's idea are men like Dr. Edward Teller.
All who followed the public statements of Dr. Sakharov were impressed with his courage. I even thought he simply lacked the instinct of self- preservation. I know now that he was so fearless because he was a man of inner freedom in a country which was not free. The roots of his courage was his erudite knowledge and his per- sonal kindness. When the Sakharovs were in their exile in Gorky, my feeling was that they were more free than we who were allowed to visit them, more free than their captors.
After his return from the exile, Dr. Sakharov plunged into public campaigning on vital issues of global importance, like nuclear safety and pre- vention of ecological catastrophes. In dealing with these issues he relied on his vast store of scientific knowledge and experience.
Here is just one example of this work. Two years after his return from the Gorky exile, in October 1988, there was a Soviet-American sem- inar in Leningrad on earthquake prediction. Dr. Sakharov addressed the participants with a report in which he suggested detonating small nuclear charges at shallow depth in earthquake- prone areas in order to reduce the accumulating tension in the crust. This idea may very well be of considerable practical importance.
In an interview for an Estonian youth newspa- per Dr. Sakharov said his might well be an exceptional career. He said he was expected to do more than he really could. "I merely tried to live up to that challenge." "Do you believe in des- tiny?", asked the reporter. "All I believe in," was the answer, "is some inner logic of events. And not only. in human life, but in the life of this world in general, i don't think there is. any such thing as destiny. Our future is uncertain and unpre- dictable. It is we ourselves who are building and shaping this future through a process of endless- ly complex interactions."
The more we learn about men like Dr. Sakharov the better we become ourselves. .Men like him are our hope for the future.