English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Ninety years ago, in 1922, Alexander Friedman (1888-1925) demonstrated forthe first time that the General Relativity equations admit non-static solutionsand thus the Universe may expand, contract, collapse, and even be born. Thefundamental equations he derived still provide the basis for the currentcosmological theories of the Big Bang and the Accelerating Universe. Later, in1924, he was the first to realize that General Relativity allows the Universeto be infinite. Friedman's ideas initially met strong resistance from Einstein,yet from 1931 he became their staunchest supporter. This essay connectsFriedman's cosmological ideas with the 1998-2004 results of the astronomicalobservations that led to the 2011 Nobel Prize in Physics. It also describesFriedman's little known topological ideas of how to check General Relativity inpractice and compares his contributions to those of Georges Lemaitre. Recentlydiscovered corpus of Friedman's writings in the Ehrenfest Archives at LeidenUniversity sheds some new light on the circumstances surrounding his 1922 workand his relations with Paul Ehrenfest.

"The Waters I am Entering No One yet Has Crossed": Alexander Friedman and the Origins of Modern Cosmology