Assignment 5. Discoverer of Expanding Universe

Overview

Alexander Friedmann was a Russian cosmologist along with being a mathematician.  He helped develop various models that explained the development of the existing universe. He provided solutions to Eintsein’s field equations that provided early evidence of the expanding universe, and the theoretical foundations for two models of the universe.  These two models include the Big Bang, along with the steady state models of the universe.  The Big Bang was a huge explosion about 13.7 years ago, is the theory in which states the declaration of the creation of the universe.  According to this theory, the universe began in a super dense, hot state and has been expanding and cooling off ever since.  Fred Hoyle coined the phrase during a 1949 radio broadcast.  The steady state model was a cosmological model created in 1948 as the main alternative to the standard Big Bang Theory.  This theory holds that the universe is expanding but the new matter and new galaxies are continuously crated in order to maintain the perfect cosmological principle (idea that the universe is isotropic and homogenous in both space and time).  Therefore it has no beginning or end. 

Biography of Alexander Friedmann

Alexander Friedmann was born on 16 June 1888 in Saint Petersburg, Russia to his father who was a ballet dancer and his mother who was a pianist. He was an excellent scholar, both in high school at the Second Saint Petersburg Gymnasium, along with Saint Petersburg State University, where he studied mathematics from the years 1906 to 1910.  He received his master's degree in pure and applied mathematics in 1914, although his research had also touched on aeronautics in theories around the magnetic field of the earth, the mechanics of liquids and theoretical meteorology.  In 1913, he was appointed to a position in the Aerological Observatory where he studied meteorology. The year after,  he attended Leipzig to study with Vilhelm Bjerknes, the leading theoretical meteorologist of the time. He participated in several flights in airships to make meteorological observations.  However, when the First World War started later that year, Friedmann volunteered to serve with the Russian air force as a technical expert and soon became a bomber pilot. Post1915, he lectured pilots on aerodynamics, and and rapidly moved up the ladder and in 1916 he became the head of the Central Aeronautical Station in Kiev, prior to moving to Moscow with the Central Aeronautical Station.   Since the Central Aeronautical Station disbanded after the Russian Revolution of 1917 and, from 1918 to 1920, Friedmann worked as a professor of theoretical mechanics at Perm University.  Friedmann returned to Saint Petersburg in 1920, since the civil war made his position very difficult at the Main Geophysical Observatory. He also took up several other concurrent appointments such as being a teacher of mathematics and mechanics at Petrograd University, a professor of physics and mathematics at Petrograd Polytechnic Institute, and lastly, as a researcher at the Petrograd Institute of Railway Engineering, the Naval Academy and the Optical Institute.

By late 1920, he had belatedly become familiar with the General Theory of Relativity by Albert Einstein, which was published several years late in war-torn Soviet Russia. In 1922, he discovered the expanding universe solution to the field equations of general relativity Einstein conducted. The expanding universe solution states that a universe in which is constantly growing in size and in which the constituent parts such as the galaxies, clusters etc. are flying even further away from each other.  It also suggests that, in the distant past, the universe was much smaller and ultimately had its beginning in a Big Bang type event. Einstein did not agree with this solution at first, and thought that the solution was erroneous.  However, he later agreed that they were in fact correct, and indeed that they shed new light on the whole subject. The expansion of the universe was finally corroborated several years later by Edwin Hubble’s observations in 1929.

3 Friedmann Models

diagram depicting Friedmann's 3 models 

Friedmann’s papers from 1924 demonstrated all three Friedmann models.  The three Friedmann models include:

1.    Describing Positive

2.    Describing Zero

3.    Describing Negative curvature of space-time

Space-time is any mathematical model that combines space and time into a single construct.  The fourth dimension of time is traditionally considered to be of a different sort than the three dimensions of space in that it can only go forwards and not backwards.  However, in Einstein’s General Theory of Relativity, space and time are seen to be essentially the same thing and can therefore be treated as a single entity.   Friedmann’s work of the 3 models supports both the theory of the Big Bang, and the Steady State theory of the universe equally.  However the steady state theory was later abandoned after the discovery of the cosmic microwave background radiation in 1985.

References:

http://www.physicsoftheuniverse.com/scientists_friedmann.html
http://www.intechopen.com/source/html/41230/media/image6.JPG
http://decodedscience.com/wp-content/uploads/2012/10/Geometry-of-Universe3.jpg
http://cdn2-b.examiner.com/sites/default/files/styles/image_content_width/hash/53/fb/53fb27bf0ac092fad6912073c2073820.jpg?itok=njtr0okk