Question

What was the major difference between Einstein’s static universe and Friedmann’s universe?

Answer 1

Before giving the difference in both the theories, let me introduce both of the genious. Albert einstein (1879-1955) was the famous scientist in the world and Aleksandr Friedmann (1888-1925) was a famous Russian mathematician and meteorologist.

Major differences between both types of universe are as follow:

1. Albert Einstein proposed a relativistic model of the universe called as Einstein universe or Einstein world or Einstein static universe.He published general theory of relativity which is the geometric theory of gravitation and current description of gravitation in modern physics.  Einstein viewed the Universe as static. Friedmann proposed an expanding Universe within the spaceteime and mathematics of general relativity.

2. When Einstein completed the general theory of relativity, Einstein applied his new theory of gravity to the universe as a whole. Assuming a universe that was static in time, and possessed of a uniform distribution of matter on the largest scales, Einstein was led to a finite, static universe of spherical spatial curvature. According to Friedmann there was no unique solution to Einstein's equations, rather there was a whole family of solutions possible.This family of solutions thus allowed for different cosmological models of the Universe.

3. In Friedmann's models the only force that is considered is gravitation. His model universes are homogeneous and isotropic (look the same in every direction). The concept of expansion and in some cases, contraction. Einstein himself had viewed the Universe as static. Friedmann thus provided the theoretical framework for an expanding Universe within the spaceteime and mathematics of general relativity. Unfortunatley he contracted typhoid and and died in 1925 during the Russian civil war before his work became widely known.