ASTB03 – Assignment 5 – Discoverer of Expanding Universe

Alexander Friedmann was born in St. Petersburg, Russia on June 16, 1888.[1] In his school life, he was one of the top students in his classes and had organized student protests against the repressive government in Russia at the time.[2] In 1913, he was appointed a position at the Aerological Observatory in Pavlovsk, where he studied meteorology.[1][3] In 1914, he completed his master’s degree in pure and applied mathematics, but had also done research on aeronautics, the magnetic field of the earth, the mechanics of liquids and theoretical meteorology.[1] The next year, Friedmann served in the Russian air force and was awarded a military cross for his work on several missions.[1][2] He would then later become the head of the Central Aeronautical Station in Kiev.[1]

At the conclusion of the First World War, Friedmann had become a professor at Perm University.[1][2] While the First World War had ended, there was still a Civil War happening in Russia, until 1920. This made it difficult for Friedmann and other Russian scientists to communicate with scientists around the world. When the Civil War ended in Russia, Friedmann was able to learn of Einstein’s Theory of General Relativity, which had already been published in Europe during the First World War, but was not known to Russia until the end of the Russian Civil War.[2][3]

The relationship between mass, space, and time was explained in a set of differential equations known as Einstein’s field equations.[3] Friedmann had begun to focus on attempting to solve these equations after learning of the Theory of General Relativity.[2] Scientists at the time believed the universe was static and that it has always been, and will always be the same size.[2] Friedmann however, looked at the universe as a fluid, made up of the same material, and spread in every direction.[3] He was then able to use Einstein’s field equations to show how the universe would act with the Theory of General Relativity.[3] Finally, in 1922, Friedmann was able to publish solutions to Einstein’s field equations.[1][2] There were three models created by Friedmann’s solution, one for each of the positive, negative, and zero curvature.[1] In the models, if the curvature was zero, then the universe would be flat, while a positive curvature would result in a sphere, and a negative curvature would be a hyperbolic space.[3] Once time was added to the equations, Friedmann saw that the curvature could be an increasing or periodic function, which gave way to the possibility of an expanding, dynamic universe, instead of the static universe that scientists believed.[2][3] Einstein originally believed that the solution had contained errors and called it “suspicious”.[1][2] Friedmann then wrote to Einstein with more detail of his work to try to convince him that the solution was in fact correct, but Einstein did not receive the letter right away because he was on a trip to Japan.[3] However, when he did receive the letter, he admitted that Friedmann was in fact correct and said, “. . . my criticism . . . was based on an error in my calculations. I consider that Mr. Friedmann’s results are correct and shed new light”.[2] The reason this was so important was because it created the basis that lead to the Big Bang Theory and Steady State Theory of the universe.[1][3]

Afterwards, Friedmann was given the job of the Director of the Main Geophysical Observatory in Leningrad.[1] While there, he taught George Gamow, who would go on to become a theoretical physicist and cosmologist.[1] Gamow is known for doing calculations that showed that complex nuclei (ie. helium) could be formed with the hydrogen from the Big Bang.[4] This, along with the creation of heavier elements within stars made it easy to accept the Big Bang Theory on the origins of the universe.[4]

Late in the 1920’s, both George Lemaître, and Edwin Hubble would find evidence of the expansion of the universe, which further supported Friedmann’s solutions.[2] Einstein would eventually remove the cosmological constant from his equations after evidence of redshifts by galaxies.[2] Arthur Eddington would also later go on to show that the static universe would be unstable, which provided further support of the expanding universe theory.[2]

Friedmann, after publishing his solution to Einstein’s field equations, would later take part in a balloon flight which reached an elevation of 7400m.[1] However, a few months later, on September 16, 1925, he would die of typhoid fever, which he may have caught while on vacation in Crimea.[1]

While Friedmann was a very important figure in modern astronomy, was not very well known in the western world, even with the significant contributions he made in his short life. One reason for this is that there was a disconnect between Russia and the western world during World War I, and also the following Russian Civil War.[1] Because of this, it was difficult to stay in contact with scientists outside of Russia. This meant learning about Einstein’s theories later than the rest of the world, and later having his work be less known around the world. Another possible contributing factor was that he died at a younger age, and may have been able to contribute more had he lived a longer life, thus gaining more publicity. Even though he is not as well-known as other scientists at the time, Friedmann provided the foundation for what we now know today about the origins of the universe.







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