And Friedman on Einstein's theory of relativity. "The waters I step into have never been crossed by anyone" Alexander Fridman and the origins of modern cosmology. Russian and Soviet mathematician, physicist and geophysicist, creator of the theory of the non-stationary Universe
Introduction
Since ancient times, mankind has been trying to understand what kind of world they live in, how big it is, what the world is. In pursuit of understanding the nature of the space in which a person lives, many different theories, concepts, assumptions were created, but in truth our civilization came close to the answer only by the 20th century.
Thanks to the work of many scientists of that time, we were able to get answers to many questions about the essence of the world, to some extent its nature. We were able to find answers to many questions, but these answers gave rise to another set of questions that we needed to find answers to.
GR (General Theory of Relativity) created by A. Einstein gave us an idea and a partial understanding of our world, the space in which we live, time, which inexorably strives forward, but even Einstein did not fully understand the magnitude, complexity and volume of which the Universe has.
But there was one person who was able to comprehend, understand and realize this value, the person who predicted the expansion of the Universe. His name is Alexander Alexandrovich Fridman.
Alexander Friedman. short biography
“If I opened a star,
I would call her Friedman ... "
Leonid Martynov
Alexander Alexandrovich Fridman- one of the founders of the modern theory of turbulence and the Soviet school of dynamic meteorology, the author of important works on the theory of relativity, mathematics and theoretical mechanics.
Born on June 16, 1888 in St. Petersburg in the family of a graduate of the St. Petersburg Conservatory (at that time a student and artist of the ballet troupe), composer Alexander Alexandrovich Fridman (1866--1909) and a piano teacher (at that time also students of the conservatory) Lyudmila Ignatievna Fridman (nee Voyachek, 1869-1953). Maternal grandfather, Ignaty Kasparovich Voyachek (1825-1916), was an organist and conductor at the Imperial Mariinsky Theatre.
In 1897, when the future scientist was 9 years old, his parents separated and later he was brought up in the new family of his father, as well as in the families of his grandfather - the medical assistant of the Court Medical District and the provincial secretary Alexander Ivanovich Fridman (1839--1910) and aunt, pianist Maria Alexandrovna Fridman (with his mother A. A. Fridman resumed relations only shortly before his death). He studied at the 2nd St. Petersburg gymnasium. In his gymnasium and student years he was fond of astronomy.
In October 1905, Friedman, together with classmate Yakov Tamarkin, sent his first mathematical work to one of the leading scientific journals in Germany, Mathematische Annalen; an article on Bernoulli numbers was published in 1906. During the revolution of 1905, he participated in political activities, was a member of the Central Committee of the Northern Social Democratic Organization of Secondary Schools in St. Petersburg, printed proclamations on a hectograph.
Fridman's classmate (at the gymnasium, later at university and postgraduate studies) and friend was Ya. V. I. Smirnov studied one class older, in the future also a mathematician, academician of the USSR Academy of Sciences, author of the popular five-volume Course of Higher Mathematics.
After graduating from the gymnasium with a gold medal, Fridman in 1906 entered the mathematical department of the Faculty of Physics and Mathematics of St. Petersburg University, from which he graduated in 1910. Was left at the Department of Pure and Applied Mathematics under prof. V. A. Steklov to prepare for a professorship.
Until the spring of 1913, Friedman studied mathematics, and also led practical classes at the Institute of Railway Engineers, and lectured at the Mining Institute. Fridman and Tamarkin, while still students, regularly attended the classes of the circle of new theoretical physics, organized in 1908 by PS Ehrenfest, who had recently arrived from Germany, whom Friedman considered, like Steklov, one of his teachers.
In 1913 he entered the Aerological Observatory in Pavlovsk near St. Petersburg and began to study dynamic meteorology (now this field of science is called geophysical hydrodynamics). In the spring of 1914 he was sent on a business trip to Leipzig, where the famous Norwegian meteorologist Wilhelm Freeman Koren Bjerknes (1862-1951), the creator of the theory of fronts in the atmosphere, lived at that time. In the summer of that year, Friedman flew airships, taking part in preparations for observing the solar eclipse in August 1914.
With the outbreak of World War I, Friedman volunteered for an aviation unit. In 1914-1917, he participated in the organization of aeronautical and aerological services on the Northern and other fronts, was a test pilot, participated in combat sorties, bombed Przemysl, and conducted aerial reconnaissance. Friedman - Knight of St. George, was awarded a golden weapon and the Order of St. Vladimir with swords and a bow. He draws up tables for precision bombing and checks them in combat.
In 1917 he was invited to lecture at Kyiv University, then he moved to Moscow. For some time he worked at an aircraft instrument factory. The war undermined his health. Doctors did not advise to go to Petrograd and he chose Perm. In November 1917, he applied for participation in the competition, and in April 1918, Fridman took the post of extraordinary professor in the department of mechanics at Perm University. For some time, A.A. Fridman worked as Vice-Rector of Perm University.
In 1920 he returned to Petrograd and worked at the Main Physical Observatory (since 1924 - the Main Geophysical Observatory named after AI Voeikov). Since 1920, A.A. Fridman taught at various educational institutions in Petrograd. Since 1923 he is the editor-in-chief of the Journal of Geophysics and Meteorology. Shortly before his death, he was appointed director of the Main Geophysical Observatory.
In 1931, by a decree of the Soviet government, A.A. Friedman was posthumously awarded the Lenin Prize.
June 16, 1888 - September 16, 1925
Russian and Soviet mathematician, physicist and geophysicist, creator of the theory of the non-stationary Universe
Biography
Born June 16, 1888 in St. Petersburg in the family of a graduate of the St. Petersburg Conservatory (at that time a student), composer Alexander Alexandrovich Fridman (1866-1909) and a piano teacher (at that time also a student at the conservatory) Lyudmila Ignatievna Fridman (nee Voyachek, 1869-1953). In 1897, when the future scientist was 9 years old, his parents separated and later he was brought up in the new family of his father, as well as in the families of his grandfather - the medical assistant of the Court Medical District and the provincial secretary Alexander Ivanovich Fridman (1839-1910) and aunt, pianist Maria Alexandrovna Fridman (A. A. Fridman resumed relations with his mother only shortly before his death).
With the outbreak of World War I, Friedman volunteered for an aviation unit. In 1914-1917 he participated in the organization of the air navigation and aerological service on the Northern and other fronts. Participated as an observer in combat missions.
Friedman was the first in Russia to understand the need to create a domestic aircraft instrument industry. During the years of war and devastation, he brought the idea to life, becoming the founder and first director of the Aviapribor plant in Moscow (June 1917).
In 1918-1920 he was a professor at Perm University. From 1920 he worked at the Main Physical Observatory (from 1924 the Main Geophysical Observatory named after A. I. Voeikov), at the same time from 1920 he taught at various educational institutions in Petrograd. From 1923 he was editor-in-chief of the Journal of Geophysics and Meteorology. Shortly before his death, he was appointed director of the Main Geophysical Observatory.
Friedman's main works are devoted to the problems of dynamic meteorology (the theory of atmospheric vortices and wind gustiness, the theory of discontinuities in the atmosphere, atmospheric turbulence), compressible fluid hydrodynamics, atmospheric physics, and relativistic cosmology. In July 1925, for scientific purposes, he flew in a balloon together with pilot P. F. Fedoseenko, reaching a record height of 7400 m for that time. general relativity course. In 1923, his book The World as Space and Time (republished in 1965) was published, introducing the new physics to the general public.
Friedman predicted the expansion of the universe. The first non-stationary solutions of Einstein's equations obtained by him in 1922-1924 in the study of relativistic models of the Universe marked the beginning of the development of the theory of the non-stationary Universe. The scientist studied non-stationary homogeneous isotropic models with a space of positive curvature filled with dust-like matter (with zero pressure). The nonstationarity of the considered models is described by the dependence of the radius of curvature and density on time, and the density changes inversely as the cube of the radius of curvature. Friedman found out the types of behavior of such models allowed by the equations of gravity, and Einstein's model of the stationary Universe turned out to be a special case. Refuted the opinion that the general theory of relativity requires the assumption of finiteness of space. Friedman's results demonstrated that Einstein's equations do not lead to a unique model of the universe, whatever the cosmological constant. From the model of a homogeneous isotropic Universe, it follows that when it expands, a redshift proportional to the distance should be observed. This was confirmed in 1929 by Edwin Hubble on the basis of astronomical observations: the spectral lines in the spectra of galaxies were shifted to the red end of the spectrum.
Friedman died in Leningrad from typhoid fever on September 16, 1925. He was buried at the Smolensk Orthodox cemetery.
The first wife of A. A. Fridman (since 1911) is Ekaterina Petrovna Fridman (nee Dorofeeva). The second wife (since 1923) - Doctor of Physical and Mathematical Sciences Natalya Evgenievna Fridman (nee Malinina), their son - Alexander Alexandrovich Fridman (1925-1983) - was born after the death of his father.
Alexander Friedman - Knight of Science
Aron Chernyak
If I opened a star
I would call her Friedman...
Friedman! Until now, he is a resident
Only a few bookshelves -
mathematician amateur,
Young meteorologist
And a military aviator
in germa
nsky front somewhere ...
The fact that he went to something
Feeling the forms of impermanence
In this hurricane world
Seen in the curvature of space
He is a galactic runaway.
The expansion of the universe?
This needs to be sorted out!
This Friedman was a scientist
With a very enviable future.
Oh shine above the sky
A new star, Friedman!
These are lines from a poem by the outstanding Russian poet Leonid Martynov (1905-1980) “If I discovered a star…” It is not so often that poets dedicate their poems to scientists; It can be said that this phenomenon is unique. What attracted L. Martynov so much in the life and work of A. Fridman? He overtook Einstein, touched the mystery of the expanding Universe, a mathematician, a meteorologist and, in addition, a combat pilot - is this not enough to inspire a poet?! Let's try to briefly talk about A. Fridman, of course, in prose.
In the tenth issue of the journal of the Air Force of the Red Army "Bulletin of the Air Fleet" for 1925, an obituary "In memory of Professor, pilot-observer A.A. Friedman". But Friedman was not just an ordinary pilot-observer: during the First World War, when his plane took off on combat duty in the sky of the northwestern front, the German front radio station transmitted a warning: “Attention! Friedman is in the air! The Germans were not worried in vain: they knew who they were dealing with ... This man was a "cosmonaut", but not in the now generally accepted sense of the word. He did not ascend into outer space, was not a conqueror of space, although in the early 1920s the very idea of interplanetary travel had already become “fashionable”, the names of N. Kibalchich, K. Tsiolkovsky, R. Goddard, G. Oberta and others were already known space exploration enthusiasts, scientific and popular science works were already published and films about upcoming space achievements were made, quite serious people were already talking about this ... Even the socio-political science fiction writer V. Ulyanov-Lenin showed interest in space topics.
The name of A. Friedman was not known to the general public, he did not become the idol of the crowd, eager for an immediate "jump into space." However, such fundamental concepts as "redshift", "recession of Galaxies", "world equations", "models of the Universe" are inextricably linked with his name. For A. Friedman was the founder of modern cosmology - the physical doctrine of the Universe as a whole. It was not easy to rise to such a scientific peak: for this it was necessary to enter into a discussion and shake the position of the brilliant Albert Einstein. The great scientist and the young professor from Petrograd never met. They crossed arms in the pages of the prestigious scientific journal Zeitschrift fur Physik (Journal of Physics). More precisely, they met in the vast expanses of the universe. And a miracle happened on this global arena: the little-known A. Friedman won - and the great Einstein nobly acknowledged that he was right. Who else can boast of such success!
A. Fridman cannot be categorized as "forgotten scientists". Articles about him are available in all Russian and most foreign encyclopedias, in which he is characterized as an outstanding physicist and mathematician. Friedman is rarely mentioned in popular science literature. Jewish encyclopedic publications, as a rule, “forgot” about Fridman, and only the Russian Jewish Encyclopedia of 1997 placed information about this remarkable scientist, and even then for some reason in an article about Father A. Fridman, a little-known musical figure.
Alexander Alexandrovich Fridman was born on June 17 (29), 1888 in St. Petersburg. In 1910 he graduated from the Faculty of Physics and Mathematics of the Moscow University and was left at the Department of Mathematics. His pedagogical and scientific activity begins. He lectures on higher mathematics and works at an aerological observatory. With the outbreak of World War I, A. Fridman joined a volunteer air squadron, taught at an aviation school, and organized an army air navigation service. In 1916, he headed the central air navigation and aerological service of the front. In all his undertakings, he showed brilliant engineering abilities and the qualities of an outstanding organizer. In 1917, Friedman took an active part in the construction of the Moscow Aviation Plant and soon became its director.
A year later, he went to Perm to provide scientific assistance to a local university, worked there as a professor and deputy rector, and created a number of technological departments. Perm University is becoming a major center of higher technical education. Since 1920, Friedman has been a professor at Petrograd University, working at the main geophysical observatory, and in 1925 he headed it. Back in 1906, at the age of eighteen, he, together with the mathematician Ya. Tamarkin, who soon became famous, completed a work on number theory, which was published on the pages of the German journal Mathematical Annals.
Immediately after the creation of the general theory of relativity by A. Einstein, A. Friedman showed the deepest interest in this great discovery, especially in the "world equations" introduced by Einstein. Based on the solution of these equations, Einstein tried to determine the geometric properties of the universe. In particular, he allowed the thesis that the world has the shape of a cylinder. Einstein also came to the conclusion that, under certain conditions, the universe is spatially limited. Naturally, such a serious and very unexpected statement, which struck contemporaries, could not be unequivocally accepted by everyone. There were criticisms that were not convincing enough: in order to disprove Einstein, a scientific charge of extraordinary strength was required. And such a "charge" exploded: in 1922, the journal "Izvestiya Fiziki" published an article "On the curvature of the space of the world." The author subjected Einstein's conception to a deeply justified and very significant criticism. He showed that Einstein's "world equations" under no circumstances can be unambiguous and with the help of these equations it is impossible to give a definite answer to questions about the form (if the word is applicable at all) of the Universe and its finiteness or infinity.
Further, the author considered the question of the radius of curvature of space. Einstein, presenting his theory, considered this radius to be a constant value. The unknown author of the article stated: the radius of curvature of space changes in time, and under this condition, the possibility of non-stationary solutions of "world equations" arises. The author proposed three options for such solutions and, accordingly, built three possible models of the Universe. Two of them - with a monotonous increase in the radius of curvature, and one of the first two allows for the expansion of the Universe from a certain point, and the second assumes an expansion from a mass that has finite dimensions. The third model is a pulsating Universe, the radius of which changes with a certain periodicity. The author recognized the infinity of the Universe, its space and mass.
deeply grounded and highly
significant criticism.
This polemical article was sent from Petrograd, signed under it - Alexander Fridman. The name said little even to specialists. However, Einstein was attentive to the new view, which rejected his claims. In the eleventh issue of the same journal, he published an article "Remarks on the work of Friedman" On the Curvature of Space "", in which he defended his positions. But some time passed, and in the sixteenth issue of the journal, a new publication by Einstein appeared on the same topic, in which he admitted his mistake and, accordingly, the correctness of Friedman. Thus ended the scientific dispute between Einstein and Friedmann.
It is interesting to note one circumstance that is very characteristic of Einstein: despite the defeat, the great physicist found it necessary to perpetuate the name of his opponent in his writings. In all subsequent editions of the famous book “The Essence of the Theory of Relativity”, Einstein specifically emphasized: “His (Friedman’s. – A.Ch.) result then received unexpected confirmation in the expansion of the star system discovered by Hubble ... The following is nothing more than a presentation of Friedmann’s idea ... Therefore, there is no doubt that this is the most general scheme that gives a solution to the cosmological problem.
The end of the controversy with Einstein, so favorable for Friedmann, stimulated his further work in the field of cosmology. They played a fundamental role in the development of this science. The universal scientific recognition of the model of the non-stationary Universe developed by Friedman occurred after the approval of the discovery by the American astronomer E. Hubble of the so-called red shift - in other words, the shift of lines towards the red part of the source spectrum. Redshift occurs when the distance between the radiation source and the observer increases. This testifies to the process of expansion of the Universe - the effect of "running away" of Galaxies in all directions is observed. In turn, this effect confirms the correctness of the assumption about the non-stationary model of the Universe.
Shortly after the death of Friedmann, the Belgian abbot J. Lemaitre (later the first president of the Pontifical Academy of Sciences), based on his ideas, created his own concept of the emergence of the Universe at a certain moment from one “father atom” - the theory of the “Big Bang” (“Big-Bang "). She received support in the works of the greatest astrophysicist A. Eddington. Currently, this model is increasingly called the Friedmann-Lemaitre model. During the years of Soviet power, this theory was declared idealistic. “It is interesting that in Stalin's times,” writes the director of the Institute of Theoretical Physics. Landau of the Russian Academy of Sciences V. Zakharov, - this theory was fought mercilessly, and those who preached it could easily end up in jail. This theory was absolutely forbidden, since consistent atheism, which was the religion of the time, is compatible only with the idea of infinite time, the infinite repetition of everything.
We, separated from Friedman's time by dozens of years, are struck by the exceptional breadth of scientific interests of this remarkable man. Figuratively speaking, he seemed to be looking for empty spaces of science in order to fill them. All of Friedman's works are marked by an outstanding intellect, they are distinguished by a high level of novelty, brilliant mathematical talent, convincing evidence, and clarity of presentation. In the field of the theory of relativity, together with V. Frederiks, he prepared fundamental works, but managed to publish only the first volume of the five planned - "Fundamentals of the Theory of Relativity". Of great interest is Friedman's book The World as Space and Time (1923), a talented popularization of the theory of relativity.
Another direction of Friedman's scientific activity is hydromechanics and hydrodynamics. In the fundamental work "Experience in the Hydromechanics of a Compressible Fluid" (1922, 1934, 1963), the author outlined a comprehensive theory of vortex motion in a fluid, the problems of possible movements of a compressible fluid when certain forces act on it, and studied the kinematic properties of a compressible fluid.
Dynamic meteorology is another area of Friedman's work. His work in this area is fundamental. In works on the theory of atmospheric vortices, an equation was derived to determine the speed of a vortex. The vertical atmospheric currents were studied, the regularities of temperature changes at different heights were established - the foundations of the theory of studying the weather and its forecasting were laid. Friedman created the foundations of the statistical theory of turbulence. He also made a significant contribution to the theory and practice of aeronautics: in 1925 he made a record flight in a balloon, reaching a height of 7400 meters. All A. Fridman's activities are characterized by the desire to bring the results of research to the end, from theory to practice.
His wife Ekaterina Fridman gave an accurate assessment of Friedman as a scientist: “The ability to peer into depth, with a wide sweep, clearly, briefly state, apply to practice or leave it in the form of a new theory, illuminate from all sides and give a new impetus to thought - these were the characteristic features of his works, and his creative thought penetrated into all the nooks and crannies of his accumulated knowledge and illuminated them with the bright light of his disciplined mind and creative imagination.
September 16, 1925 A.A. Friedman died in the prime of life from typhoid fever. He was only 37 years old. The scientist's death caused a flood of obituaries in scientific journals in Russia and other countries. Among the authors of these commemorative articles are the great mathematician V. Steklov, a prominent mechanic, an expert in the field of the theoretical foundations of rocket technology I. Meshchersky, and many others. In 1931, A. Fridman was posthumously awarded the highest Soviet award for scientific activity. And the poetic wish of Leonid Martynov came true only in part: if not a star, then one of the objects on the moon is named after Alexander Fridman.
The painting by A. Tyshler "Cosmos Series" was used in the design. 1970
Monthly literary and journalistic magazine and publishing house.
Who Invented Modern Physics? From Galileo's pendulum to quantum gravity Gorelik Gennady Efimovich
Alexander Fridman: "The Universe does not stand still"
In the spring of 1922, the Zeitschrift für Physik, the main physics journal of that time, published an appeal “To the Physicists of Germany”. The Board of the German Physical Society reported on the difficult situation of colleagues in Russia, who had not received German journals since the beginning of the war. Since German-speaking physics was then in the lead, it was a severe information hunger. German physicists were asked for publications of recent years to be sent to Petrograd.
In the same journal, twenty-five pages below, there is an article received from Petrograd and contradicting the call for help. The name of the author - Alexander Fridman - was unknown to physicists, but the article entitled "On the curvature of space" claimed a lot. The author argued that the solutions of Einstein and de Sitter, published five years earlier, are not the only possible, but only very special cases, that the density, which is constant throughout space, does not have to be constant in time. It was in this article that the "expansion of the Universe" was first mentioned. It will become an astronomical fact seven years later; it remains to be measured and calculated how many billions of years the expansion lasted and what is the distance to the cosmic horizon, but the horizon of science was expanded in 1922 by 34-year-old Alexander Fridman.
Alexander Fridman
If, having plucked up courage, we liken the Universe to a pendulum, then the solutions of the cosmological problem obtained by Einstein and de Sitter can be compared with the positions of the pendulum at rest. There are two such positions: when the pendulum just hangs and when it stands “upside down”. And Friedman discovered that the universal pendulum does not have to rest at all, it is much more natural for it to move. And he calculated the law of motion based on Einstein's equations. At the same time, he showed that motion is also possible when the cosmological constant is equal to zero. The universe can both expand and contract depending on its density and speed at some point. So,
Let us now compare the Universe to a rubber ball, remembering the essence of Einstein's theory of gravity - the connection between the curvature of space-time and the state of matter. Einstein, one might say, discovered how the radius of the ball is related to the density and elasticity of rubber. He started with a ball whose radius is constant.
Simplification of the problem is one of the main tools of the theoretician. In the darkness of ignorance, sometimes they look for a key under a lamppost only because it is impossible to look in other places. Oddly enough, such searches are successful. Even the author of the equations cannot solve complex equations for an arbitrary case. Einstein started with the simplest case - with the most homogeneous geometry, although the observations of astronomers in 1917 did not speak of the homogeneity of matter in the universe.
But his second assumption - about the immobility of the ball - looked as obvious as the constancy of the starry sky. Only against the background of fixed stars did astronomers manage to study the motion of the planets, and physicists to find the laws governing this motion. And finally, the eternity of the Universe habitually, on behalf of science, opposed the religious idea of the creation of the world.
Friedman raised his hand to this axiom.
Let us return to the rubber, more precisely to Riemann, ball of the Universe, which Einstein picked up in 1917. Having made his simplifying assumptions, Einstein discovered with chagrin that in fact there was no ball in his hands, there were only disembodied axioms. He discovered that the gravity equations he had suffered two years ago did not have the expected solution! Any child could help him, knowing that the real life of a rubber balloon begins when it is inflated. But Einstein - not without reason the great physicist - himself thought of this. The cosmological constant he added to the equations became the air, the elasticity of which balanced the elasticity of the universal ball.
Having become acquainted with Einstein's cosmology, Friedman appreciated the enormity of the posed physical problem, but its mathematical solution caused him doubts. Of course, the pendulum can be at rest, but this is only a special case of its general oscillatory motion. Or in the language of mathematics: a differential equation, like Einstein's equation of gravity, usually has a whole class of solutions depending on the initial conditions.
In his article, Friedman showed how the spherical space-time changes in accordance with its "elasticity", determined by the Einstein equation. In one of the possible solutions, the radius of the Universe increased, starting from zero, to a certain maximum value, and then again decreased to zero. What is a sphere of zero radius? Nothing! And Friedman wrote:
Using an obvious analogy, we will call the time interval during which the radius of curvature from 0 reached R 0 , time elapsed since the creation of the world.
It’s easy for a mathematician to say so, but for the physicist Einstein, the result was so strange that ... he didn’t believe him, found an imaginary error in the calculations and reported this in a brief note in the same journal. Only after receiving a letter from Friedmann and doing the calculations again, Einstein recognized the results of his Russian colleague and in the next note called them "shedding new light" on the cosmological problem. For historians, Einstein's mistake sheds light on the scope of Friedmann's work.
Einstein on the work of A. Friedman
Note on the work of A. Friedman "On the curvature of space" (09/18/1922)
…The results on the dynamical world contained in the mentioned work seem doubtful to me… In fact, the solution indicated in it does not satisfy the field equations. The significance of this work lies in the fact that it proves the constancy of the radius of the world in time ...
To the work of A. Fridman "On the curvature of space" (31.05.1923)
In a previous note, I criticized the above work. However, my criticism, as I learned from Friedman's letter, was based on a calculation error. I think Friedman's results are correct and shed new light. It turns out that the field equations allow, along with static ones, also dynamic (time-varying) solutions for the structure of space.
Today's student can go through Friedman's calculations on two pages and think skeptically: “Well, what did he actually do?! I solved the equation, that's all! This is how students solve equations. Yes, Einstein's equations are more complicated than quadratic ones, but Friedman is not a schoolboy either. Einstein found one "root" of his equations, Friedman - the rest.
So, maybe talking about the greatness of Fridman's work is an echo of those years when the guardians of Russian glory at any cost looked for domestic discoverers? No, if only because those very guardians tried to forget about the domestic contribution to cosmology, which was declared a servant of the "clergy", in the language of Soviet ideology. If Friedman himself wrote about the "creation of the world", then the guardians of the state atheistic religion could not allow such freedom of speech. Cosmology in the USSR was closed in 1938 and allowed only after the death of Stalin.
Formulas in physical works have a life of their own. This is both good and not so good. Good, because scientific prejudices and optional interpretations are more easily separated from formulas. But, on the other hand, looking at the formulas written many years ago, it is difficult to delve into the meaning that was put into them when they appeared.
Friedman's work is not just another cosmological solution that has been shelved alongside Einstein's first solution. Friedman opened up the depth of the cosmological problem by discovering that change is a generic property of the universe. Thus the concept of evolution was extended to the most comprehensive object. In addition, a question arose that still does not have a convincing answer: how does the multiplicity of cosmological solutions of the theory of gravity correlate with the fundamental uniqueness of the Universe itself?
Was Friedman's result a stroke of luck or a reward for courage?
He did his first scientific work, while still a schoolboy, in the purest mathematics - in number theory. After graduating from the mathematical department of the university, he was engaged in dynamic meteorology - the science of the most chaotic processes in the sublunar world, simply speaking, weather forecasting. The mathematics of his science resembled the mathematics of Einstein's theory of gravity. And most importantly - it was easier for him, a mathematician, to resist the authority of the great physicist and doubt his results.
So Friedman is a pure mathematician? Not only. While still a student, he participated in the "Circle of New Physics" under the guidance of Paul Ehrenfest, who was then living in Russia, a friend of Einstein.
History took care of other favorable circumstances. During the Civil War, due to a shortage of teachers, Friedman taught courses in physics and Riemannian geometry. And in 1920, fate brought him together with Vsevolod Frederiks. The World War found this Russian physicist in Germany. The sad fate of a subject of an enemy power would have awaited him, if not for the intercession of Hilbert, the famous German mathematician. As a result, Frederiks became his assistant for several years - just when the creation of the theory of gravity was being completed and when Einstein came to Hilbert to discuss his theory. Fredericks was a witness to all this.
Until 1922, German physicists tried to help their colleagues in Russia. Ehrenfest was especially concerned about this. In the summer of 1920, his letter arrived in Petrograd, the first after a long break. In August 1920, Friedmann replied to Ehrenfest that he was studying the theory of relativity and was going to study the theory of gravity.
A boom around the new theory was already raging in the world - after the deflection of light rays from distant stars predicted by Einstein was confirmed. Popular pamphlets about the new theory began to appear, including Einstein's own book. In the author's preface to the Russian translation, published in Berlin in the autumn of 1920, we read:
More than ever, in this troubled time, everything that can bring people of different languages and nations closer together should be taken care of. From this point of view, it is especially important to promote a lively exchange of artistic and scientific works even under the current difficult circumstances. That is why I am especially pleased that my little book appears in Russian.
The bilateral exchange of physical and mathematical ideas in cosmology took place surprisingly quickly.
So who was the founder of dynamic cosmology - a mathematician or a physicist? A person who knew him well said about Friedman better than others: “A mathematician by education and talent, he was eager to apply the mathematical apparatus to the study of nature both in his youth and in his mature years.”
To apply the mathematical apparatus to such a unique volume as the Universe, courage is needed, which is not taught in either mathematics or physics departments. She either exists or she doesn't. Friedman's courage is visible to the naked eye: he voluntarily went to the front - to aviation, and being already a professor (and the author of a new cosmology), he participated in a record flight in a balloon.
So, talent, knowledge and courage. Such a combination is quite worthy of an award, which is sometimes called luck, sometimes - favorable historical circumstances. But Friedman was not destined to live until the time when the scale of his discovery became clear. A talented and courageous man died at the age of 37 from typhoid fever.
Seven years later, in the diary of Academician V.I. Vernadsky, an entry appeared:
Conversation with Verigo about A.A. Fridman. He died early, maybe a brilliant scientist, which B.B. Golitsyn described to me extremely highly in 1915 and then I paid attention to him. And now - in connection with my current work and his idea of an expanding pulsating universe - I have read what is available to me. A clear, deep thought of a widely educated, God-gifted person. According to Verigo - his comrade and friend - he was a charming personality, a wonderful friend. He got along with him at the front. At the beginning of the Bolshevik regime, Fridman and Tamarkin, his friend, but much lighter than him, were expelled from the University. At one time, Friedman wanted to run away with Tamarkin: maybe he would have survived?
After the German physicist, the Dutch astronomer, and the Russian mathematician, the next important contribution to cosmology was made by American astronomers.
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Russian and Soviet mathematician and geophysicist A.A. Friedman was born on June 16 (28), 1888 in St. Petersburg into a musical family. His father was a corps de ballet dancer at the Imperial St. Petersburg Theatres, and his mother, Lyudmila Voyachek, was a pianist, a graduate of the conservatory, the daughter of a famous Czech musician and composer. However, little Alexander was attracted not by music, not by theater, from an early age he was fond of mathematics. In school and student years, a passion for astronomy was added to this. In 1906, Alexander Fridman graduated from the 2nd St. Petersburg gymnasium with a gold medal and entered the mathematical department of the Faculty of Physics and Mathematics of St. Petersburg University. In the same year, 18-year-old Alexander published his first mathematical work in one of the leading scientific journals in Germany "Mathematical Annals" ("Mathematische Annalen"). The years of study at the university were decisive for A.A. Fridman. His teacher, reliable protection and support was the brilliant mathematician Vladimir Andreevich Steklov, whose name is now the Mathematical Institute of the Academy of Sciences. Professor Steklov, who moved to St. Petersburg from Kharkov, was an unusually bright person, a future academician and vice-president of the Russian Academy of Sciences. He had a huge influence on the formation of a young scientist.
While still a student of the Faculty of Physics and Mathematics of St. Petersburg University, A.A. Friedman wrote a number of works, of which one - "Investigation of indefinite equations of the second degree" - was awarded a gold medal in 1909. In 1910, Alexander graduated from St. Petersburg University and, on the recommendation of V.A. Steklova, together with his friend, Ya. Tamarkin, was left at the Department of Pure and Applied Mathematics to prepare for a professorship. Until the spring of 1913, Friedman studied mathematics - led practical classes at the Institute of Railway Engineers (1910-1914), lectured at the Mining Institute (1912-1914). And in the spring of 1913, after passing the master's exams, he went to work at the Aerological Observatory of the Russian Academy of Sciences in Pavlovsk near St. Petersburg and began to study methods of observing the atmosphere, dynamic meteorology (now this field of science is called geophysical hydrodynamics). In addition to weather forecasting and dynamic meteorology, he had to get acquainted with the theory of terrestrial magnetism. Soon he became an outstanding specialist in meteorology and related fields. In 1913, Friedman published in the "Geographical Collection" a very important work "On the distribution of air temperature with height." In this work, he theoretically considered the question of the existence of an upper temperature inversion (in the stratosphere).
In the spring of 1914, Friedman was sent for an internship to Leipzig, where the famous Norwegian meteorologist Wilhelm Freeman Koren Bjerknes, the creator of the theory of fronts in the atmosphere, lived at that time. In the summer of that year, Friedman flew airships, taking part in preparations for observing the solar eclipse in August 1914. With the outbreak of World War I, Friedman volunteered for an aviation unit. In 1914-1917, he participated in the organization of the air navigation and aerological service on the Northern, Southwestern and other fronts. Friedman repeatedly participated as an observer pilot in combat flights and reconnaissance operations.
Having mastered the profession of a pilot, A.A. Fridman teaches at an aviator school in Kyiv. In 1917 he was invited to lecture at Kyiv University, and then he moved to Moscow. For some time he worked at an aircraft instrument factory. The war undermined his health, Friedman was diagnosed with heart disease. The doctors advised against going to Petrograd, and he chose Perm. In November 1917, he applied for participation in the competition, and on April 13, 1918, Fridman took the position of an extraordinary professor in the department of mechanics at Perm University. Until 1920, Professor A.A. Friedman worked as Vice-Rector of the University of Perm, taught courses in differential geometry and physics.
In May 1920, Alexander Fridman took an academic leave and left for Petrograd. The life of a young scientist in the first years after the Revolution was very difficult. At one time he wanted to flee abroad with Tamarkin, who eventually emigrated alone. But Friedman was lucky, in Soviet Russia he was given the opportunity to work. In 1920, in Petrograd, he began working at the Main Physical Observatory (since 1924 - the Main Geophysical Observatory named after A.I. Voeikov), at the same time he taught at various educational institutions of Petrograd - at the Polytechnic Institute (1920-1925), the Institute of Railway Engineers (1920-1925), etc. In December 1920, the scientist resigned his duties as a professor of mechanics at Perm University completely.
In 1923 A.A. Friedman was appointed editor-in-chief of the Journal of Geophysics and Meteorology. The main works of A.A. Friedman are devoted to the problems of dynamic meteorology (the theory of atmospheric vortices and wind gustiness, the theory of discontinuities in the atmosphere, atmospheric turbulence), hydrodynamics of a compressible fluid, atmospheric physics and relativistic cosmology. In July 1925, for research purposes, he flew into the stratosphere in a balloon together with pilot P.F. Fedoseenko, having reached a record height of 7400 m at that time, Fridman was one of the first to master the mathematical apparatus of Einstein's theory of gravity and began to teach a course in tensor calculus at the university as an introductory part to the course of general relativity. In 1923, his book The World as Space and Time (republished in 1965) was published, introducing the new physics to the general public.
Friedman's scientific activity was concentrated mainly in the field of theoretical meteorology and hydrodynamics. In these areas, his brilliant mathematical talent, his invariable desire and ability to bring the solution of theoretical problems to a concrete, practical application, manifested itself. A.A. Friedman is one of the founders of dynamic meteorology. He also dealt with the application of the theory of physical processes in the atmosphere to aeronautics. He devoted a lot of energy to the search for patterns, perhaps the most chaotic processes in the world - processes in the earth's atmosphere that make the weather. Despite the physical-sounding words, he was engaged, in essence, in mathematics - equations in partial derivatives.
Friedman's main work on hydromechanics is his work "Experience in the hydromechanics of a compressible fluid" (1922). In it, he gave the most complete theory of vortex motion in a fluid, considered, and in a number of cases solved the important problem of the possible movements of a compressible fluid under the action of certain forces on it. This fundamental research allows Friedman to be considered one of the creators of the theory of compressible fluids. In the same work, Friedman derived a general equation for determining the velocity vortex, which has become fundamental in the theory of weather forecasting.
In the spring of 1922 in the main physical journal of that time - "Zeitschrift fur Physik" appeared an appeal "To the German physicists". The Board of the German Physical Society informed about the difficult situation of colleagues in Russia, who had not received German journals since the beginning of the war. Since the leading position in the then physics was occupied by German-speaking scientists, it was a question of many years of information hunger. German physicists were asked to send publications of recent years to the indicated address in order to send them later to Petrograd. However, in the same journal, only twenty-five pages below, there was an article received from Petrograd and, at first glance, contrary to the call for help. The name of the author - A. Fridman - was unknown to physicists. His paper entitled "On the curvature of space" dealt with the general theory of relativity. More precisely, its most grandiose application: cosmology.
It was in this article that the "expansion of the Universe" was born. Prior to 1922, such a phrase would have looked completely absurd. Of course, the fact that the expansion of the universe began billions of years ago, astrophysics had yet to learn; still to be measured and calculated; still had to reflect on the problem of the horizon of the universe. But this idea was put forward for the first time in 1922 by the thirty-four-year-old Alexander Fridman. In his work "On the curvature of space" Friedman essentially gave an outline of the main ideas of cosmology: about the homogeneity of the distribution of matter in space and, as a consequence, about the homogeneity and isotropy of space-time, i.e. about the existence of "world" time, for which at each moment the metric of space will be the same at all points and in all directions. This theory is important primarily because it leads to a fairly correct explanation of the fundamental phenomenon - the redshift effect. The solution of the field equations obtained by Friedman under the indicated assumptions is a model for any cosmological theories.
It is interesting to note that the author of the theory of relativity, Einstein, initially believed that the cosmological solution of the field equations should be static and lead to a closed model of the Universe. In September 1922, he criticized Friedman's work: "The results on the non-stationary world contained in the mentioned work seem to me suspicious. In fact, it turns out that the solution indicated in it does not satisfy the field equations." Einstein did not believe Friedmann's results. Considering his cosmological picture implausible, he easily, but, alas, without any reason, found an imaginary error in the calculations of the Petrograd scientist. Only after receiving a letter from Friedmann, who defended his innocence, and having done the calculations again, Einstein in May 1923 recognized the results of his Russian colleague and in a special note called them "shedding new light" on the cosmological problem. And for posterity, the very error of Einstein sheds light on the meaning and scope of Friedmann's work.
The modern theory of gravity (general relativity) was created by Albert Einstein in 1915. According to this theory, under the influence of the mass and energy of bodies, space (more precisely, space-time) is curved, which, in turn, leads to curvature of the trajectories of bodies, which is perceived by us as a manifestation of gravity. Immediately after the emergence of the theory of relativity, its creator tried to apply it to the universe as a whole, but this attempt was unsuccessful. And now, after 7 years, an unknown author from Soviet Russia - a country seemingly isolated from world science - boldly asserts that Einstein's result is not at all necessary, but is a very special case. Friedman was the first to reject the dogma about the immutability of the Universe, which had dominated the minds of researchers since ancient times. His conclusions were so unusual that Einstein at first disagreed with him and claimed that he had found an error in his calculations.
Studying the general theory of relativity in Russia before 1920 was difficult: there were no foreign publications or reviews in domestic journals. And the real boom around the new theory was already raging in the world. It began in 1919, immediately after the confirmation by English astronomers of the deflection of light rays from distant stars predicted by Einstein. And the triumph of the theory of relativity nevertheless reached Russia. Popular pamphlets about the new theory began to appear. One of the first was a book by Einstein himself. The author's preface to the Russian translation, published in Berlin and dated November 1920, said: lively exchange of artistic and scientific works, even under such difficult circumstances. Therefore, I am especially pleased that my little book appears in Russian. "
Friedman's preoccupation with general relativity was by no means accidental. In the last years of his life, he, together with Professor V.K. Frederiks (1885-1944) began to write a multi-volume textbook on modern physics, which opened with the book "The World as Space and Time", dedicated to the theory of relativity, the knowledge of which Friedman considered the cornerstone of physical education. It is surprising how Friedman managed to master the theory according to its popular presentation in only a year and a half, but already in August 1920 he wrote to his teacher and colleague P. Ehrenfest: “I studied the axiom of the small [special] principle of relativity ... I really want to study the big [general ] the principle of relativity, but there is no time". Friedman's work on the general theory of relativity provided a dynamical model of the universe and for the first time made it possible to explain the structure and development of the world as a whole. But it is unlikely that Friedmann's cosmology would have appeared in 1922 if it were not for the physicist Fredericks. It is he who owns the first exposition of the general theory of relativity in Russia. His 1921 review in Advances in the Physical Sciences, as well as several other articles on general relativity, may have helped Friedman master this theory.
Obtained by Friedman in 1922-1924, the first non-static solutions of Einstein's equations in the study of relativistic models of the Universe marked the beginning of the development of the theory of a non-stationary, moving apart or pulsating Universe. The scientist studied non-stationary homogeneous isotropic models with a space of positive curvature filled with dust-like matter (with zero pressure). The nonstationarity of the considered models is described by the dependence of the radius of curvature and density on time, with the density changing inversely as the cube of the radius of curvature. Friedman elucidated the types of behavior of such models allowed by the equations of gravitation, and Einstein's model of the stationary Universe turned out to be really only a special case. He refuted the notion that general relativity requires the assumption of a finite space. Having solved the equations of Einstein's theory of gravity, taking into account the cosmological principle, Friedman showed that the Universe cannot be unchanged, depending on the initial conditions, it must either expand or contract. He was the first to give a correct order of magnitude estimate of the age of the universe.
Friedman's results demonstrated that Einstein's equations do not lead to a unique model of the universe, whatever the cosmological constant. From the model of a homogeneous isotropic Universe, it follows that when it expands, a redshift proportional to the distance should be observed. In 1927, the Belgian scholar and Catholic abbot Georges Lemaitre came to the same conclusions as Friedman. Lemaitre paid great attention to the comparison of theory and observations, for the first time indicating that the expansion of the Universe can be observed using redshift in the spectra of galaxies. Thus, the expansion of the Universe was predicted theoretically, on the basis of the theory of relativity, first by Friedmann and a little later by Lemaitre. It was one of the most brilliant examples of predictions in the history of science. In 1929, Edwin P. Hubble, on the basis of astronomical observations, confirmed that the spectral lines in the spectra of galaxies were shifted to the red end of the spectrum. So astronomers, who did not pay attention to Friedman's theory, were convinced that he was right. But Alexander Fridman, unfortunately, did not live to see the discovery of Hubble's law. Already after the discovery of Hubble, it was shown that the non-stationarity of the Universe actually follows from the law of universal gravitation (discovered by Isaac Newton at the end of the 17th century), more precisely, from the most general property of gravity, which consists in the fact that this force only attracts, but does not repel bodies .
In February 1925 A.A. Friedman was appointed director of the Main Geophysical Observatory, but held the position for less than a year. Died A.A. Friedman in Leningrad from typhoid fever on September 16, 1925. He was only 37 years old. The outstanding scientist was buried at the Smolensk Orthodox cemetery. Friedman's work was nevertheless appreciated, although many in the USSR called cosmology "the servant of obscurantism." In 1931, by a decree of the Soviet government, A.A. Friedman was posthumously awarded the Lenin Prize.
Alexander Alexandrovich Fridman, a talented Soviet scientist, one of the founders of modern dynamic meteorology, the modern theory of turbulence and the theory of a non-stationary Universe, was a very brave person. He volunteered for the Russian-German front, and being already a professor (and the author of a new cosmology), he participated in a record-breaking balloon flight. But Friedman was not destined to live to see the true scale of his discovery, which had so widely expanded the horizon of science. At the same time, let's not forget in which country and at what time the "expanding Universe" managed to be born.
On May 31, 1923, Albert Einstein wrote: “In a previous note, I criticized the work named above, but my criticism, as I was convinced from Friedmann’s letter, was based on an error in calculations. I consider Friedmann’s results to be correct and shed new light. It turns out that the equations fields allow, along with static, also dynamic (i.e., time-varying) solutions for the structure of space."
