Discovery of the Expanding Universe

For many centuries, scientists and astronomers have been battling over the question of how old and big the universe is? The ancient Greek civilizations came to the realization of how difficult it was to vision a infinite universe and what it would look like.

Georges Lemaitre

Sourced From: http://www.physicsoftheuniverse.com/scientists_lemaitre.html

Georges Lemaitre was a catholic priest and a Belgium cosmologist. He was born in 1894 in Charleroi, Belgium and even as a young boy he had a passion for science[1]. He completed his primary education at College du Sacre-Coeur which was located in Charleroi and later wen on to study at the catholic university of Louvain focusing on civil engineering at the age of 17[2]. As World War 1 began it unfortunately interrupted his education as he served as a artillery officer and witnessed the first poison gas attack in history. After the war he returned back to school and decided to focus his studies theoretical physics[1]. During the same time of his schooling he also worked on becoming a priest and by the year 1923 he was ordained a catholic priest. After being ordained he continued on in school to graduate studies in Astronomy at University of Cambridge which is located in England[2]. In 1924 he migrated to America and studied at the Massachusetts Institute of Technology. In the 1925, at the age of 31[1], Georges Lemaitre became a professor at the University of Louvian where he originally completed his studies at. Due to an injury he sustained in war, he was able secure his position as a teacher and he had a strong passion to teach[2]. Lemaitre had very strong religious beliefs but his love for science was that much stronger[3]. Einstein had already theorized about General Relativity and in 1927 Georges Lemaitre published a research paper that went unheard of but it went in depth in a solution to the equations of General Relativity specifically the case of an expanding universe.

Unfortunately, a Russian scientist by the name Alexander Friedmann had already derived he solution prior in 1922 which is 5 years earlier. Although Friedmann had a higher interest in the physics and mathematics of the solutions and possible expanding and contracting universes theoretically. Friedmann did not apply his solution to the physical universe. However, Lemaitre produced his solution with the sole purpose of explaining the cosmos and he realized that his solutions predicted the expansion of the real universe.

Edwin Hubble, another famous astronomer, in 1929 published his official report after discovering a redshift in the light emitted from distant galaxies further proving Lemaitres expanding universe theory. Lemaitre published his research in 1927 but it wasn't until astronomer Arthur Eddington who widely publicized the theory on again in 1931 by translating it and republishing it in English.

Later that year, Lemaitre further explored into our expanding universe and came to bold proposal that the universe originated at one point as a single particle. This theory came to be known as " The Big Bang Theory"

This is theory had some friction with other scientist when it was initial proposed. Einstein did not approve of the theory initially because he didn't agree with the physics but he did accept the argument that the static model that he proposed could explain indefinitely into the past. Although the theory caught on in later years by the media and Lemaitre obtained much praise for it.

Lemaitre eventually gave up his teaching career and retired but still continued to work on his calculations and developed an interest in computer language and sciences. He passed away on June 20, 1966 after the discovery of cosmic radio microwaves which further proved his theory[2].


Friedmann

Sourced From: http://www.physicsoftheuniverse.com/scientists_friedmann.html

Alexander Friedmann was born on June 16, 1888 in Russia and he known as a cosmologist and mathematician. Through out his career he developed many model that explained the universe and its development. He is also widely known in the scientific communtiy for his solutions to Albert Einstein's general relativity equations which provided early evidence of the Big Bang Theory and steady state model of the universe.

Alexander excelled in his studies both in highschool and at Saint Petersburg State University. Friendmann studied mathematics in university from 1906 to 1910 as well as attending Paul Ehrenfest's modern physics seminars. These seminars discussed in great detail about quantum theory, relativity, and statistical mechanics. In 1914 he graduated and received his master's degree in applied and pure mathematics.

While completing his graduate studies in 1913 he was given a position at the Aerological Observatory in Saint Petersberg, which was known for meteorology. At this observatory he studied theoretical meteorology and took part in many expeditions around the earth skies making meteorological observations. As Friedmann graduated, that same year the world war 1 had began and Alexander Friedmann decided to volunteer for the Russian army, specifically in the air force as a bomber pilot. After 1915 he decided to lecture pilots on the topic of aerodynamics and later taught mathematics and mechanics at Petrograd University. Once a professor he became very aware with Einsteins Theory of Relativity and in 1922 he discovered the solutions to the field equations of the expanding universe[4]. Einstein did not approve of the calculations that Friedmann made and sent a letter to the German Physics Journal saying that Friedmann's work was suspicious. Afterwords Friend sent Einstein proof of his work in a detailed letter and six months later Einstein wrote in the journal and apology saying that he himself made mistakes in his calculations.[5]

Friedmann published papers in 1924 which demonstrated 3 models of the universe with positive, zero, and negative space time curvature. These cosmological models helped explain general relativity and the big bang theory. In 1924 he also became a director of Main Geophysical Observatory in Leningrad where he met George Gamow who was a Russian physicist and cosmologist and he stuided under Friedmann for a number of years. Unfortunately for Alexander Friedmann on September 16, 1925 he was diagnosed with typhoid fever and suffered a tragic death[4].

George Gamow

Sourced From: http://www.physicsoftheuniverse.com/scientists_gamow.html

Geogre Gamow, born on March 4, 1904, was theoretical physicist who studied under Alexander Friedmann. He had many predictions about the cosmic microwave background radiation and he explained about the levels of hydrogen and helium in the universe. The explanations provided important evidence and support to the Big Bang Theory.

In 1948, George Gamow published a research paper that was very important in the world of theoretic physics. His paper about the universe was entitled "The Origin of Chemical Elements" and in it he explains the present levels of the element hydrogen and helium saying that they made up 99% of all matter in the universe. He also mentioned that this make up of the universe was due to the reactions that occured in the initial stages of the Big Bang. In the same paper he published a prediction of the cosmic microwave background radiation saying that after billions of years the radiation filling the universe would have cooled down to about 5 degrees above absolute zero. Surprisingly, in 1965 when cosmic microwave background radiation was accidentally discovered, that they were 2.7 degrees above absolute zero which was very accurate to the predictions.[6]


3 models of the Universe

Soured from: http://abyss.uoregon.edu/~js/cosmo/lectures/lec15.html

Positive Curvature - Spherical

Negative Curvature - Hyperbolic or saddled shape

Zero curvature - flat

According to the Friedmann Equations the shape of the universe depended on the overall mass / energy in relation to critical density [5]

Sources:

1. http://www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/p_lemaitre.html
2. http://www.pbs.org/wgbh/aso/databank/entries/dp27bi.html
3. http://www.physicsoftheuniverse.com/scientists_lemaitre.html
4. http://www.physicsoftheuniverse.com/scientists_friedmann.html
5. http://www.decodedscience.com/alexander-friedmann-unsung-hero-of-modern-cosmology/19423
6. http://www.physicsoftheuniverse.com/scientists_gamow.html
7. http://abyss.uoregon.edu/~js/cosmo/lectures/lec15.html