View source for Alexander Friedmann

{{short description|Russian and Soviet physicist and mathematician (1888–1925)}}
{{About|the Russian cosmologist|the Russian astrophysicist|Alexei Fridman|the Polish Orthodox Jewish rabbi|Alexander Zusia Friedman}}
{{family name hatnote|Alexandrovich|Friedmann|lang=Eastern Slavic}}
{{Infobox scientist
| name              = Alexander Friedmann
| native_name       = {{nobold|Александр Фридман}}
| native_name_lang  = ru
| image             = Aleksandr Fridman.png
| image_size        = 
| caption           = 
| birth_name        = Alexander Alexandrovich Friedmann
| birth_date        = {{Birth date|1888|6|16}}
| birth_place       = [[Saint Petersburg]], [[Russian Empire]]
| death_date        = {{death date and age|1925|9|16|1888|6|16}}
| death_place       = [[Leningrad]], [[Russian SFSR]], Soviet Union
| residence         = 
| citizenship       = 
| nationality       = Russian
| ethnicity         = 
| field             = [[Mathematics]] and [[physics]]
| work_institutions = [[Petrograd Polytechnical Institute]] <br/> Main Geophysical Observatory
| alma_mater        = [[St. Petersburg State University]]
| doctoral_advisor  = [[Vladimir Steklov (mathematician)|Vladimir Steklov]]
| doctoral_students = {{plainlist|
*[[George Gamow]]
*[[Nikolai Kochin]]
*[[Pelageya Polubarinova-Kochina]]}}
| known_for         = {{plainlist|
*[[Friedmann equations]]
*[[Friedmann–Lemaître–Robertson–Walker metric]]}}
| author_abbrev_bot = 
| author_abbrev_zoo = 
| influences        = 
| influenced        = 
| prizes            = 
| religion          = 
| footnotes         = 
| signature         = Aleksandr Fridman signature.png
| spouse            = Natalia Malinina
}}
{{Cosmology|scientists}}
'''Alexander Alexandrovich Friedmann''' (also spelled '''Friedman''' or '''Fridman'''; {{IPAc-en|ˈ|f|r|iː|d|m|ə|n}}; {{langx|ru|Алекса́ндр Алекса́ндрович Фри́дман}}; {{OldStyleDate|June 16|1888|June 4}} – September 16, 1925) was a Russian and Soviet [[physicist]] and [[mathematician]]. He originated the pioneering theory that the [[expanding universe|universe is expanding]], governed by a set of equations he developed known as the [[Friedmann equations]].

==Early life==
Alexander Friedmann was born to the composer and ballet dancer Alexander Friedmann (who was a son of a baptized [[Jewish]] [[cantonist]]) and the pianist Ludmila Ignatievna Voyachek (who was a daughter of the Czech composer Hynek Vojáček).<ref>{{cite book |title=Mathematical Physics: A Modern Introduction to Its Foundations |last=Hassani |first=Sadri |date=2013 |publisher=[[Springer Science+Business Media]] |isbn=9783319011950 |access-date=May 22, 2021 |url=https://books.google.com/books?id=uRa4BAAAQBAJ&dq=friedmann+voj%C3%A1%C4%8Dek&pg=PA1166}}</ref> Friedmann was baptized into the [[Russian Orthodox Church]] as an infant, and lived much of his life in [[Saint Petersburg]].

Friedmann obtained his degree from [[St. Petersburg State University]] in 1910, and became a lecturer at [[Saint Petersburg Mining Institute]].

From his school days, Friedmann found a lifelong companion in [[Jacob Tamarkin]], who was also a distinguished mathematician.<ref>Pyenson L. Book review. ''Physics Today'' [serial online]. September 1994; '''47'''(9):93. Available from: MasterFILE Premier, Ipswich, MA. Accessed October 18, 2012.</ref>

==World War I==
Friedmann fought in [[World War I]] on behalf of [[Imperial Russia]], as an army aviator, an instructor, and eventually, under the revolutionary regime, as the head of an airplane factory.<ref>Pyenson L. Book review. ''Physics Today'' [serial online]. September 1994;'''47'''(9):93. Available from: MasterFILE Premier, Ipswich, MA. Accessed October 18, 2012.</ref>

==Professorship==
Friedmann in 1922 introduced the idea of an expanding universe that contained moving matter. Correspondence with Einstein suggests that Einstein was unwilling to accept the idea of an evolving Universe and worked instead to revise his equations to support the static, eternal Universe of Newton's time.  In 1929 Hubble published the [[Hubble's law|redshift vs distance relationship]] showing that all the galaxies in the neighborhood recede at a rate proportional to their distance, formalizing an observation made earlier by [[Carl Wilhelm Wirtz]]. Unaware of Friedmann's work, in 1927 [[Belgians|Belgian]] astronomer [[Georges Lemaître]] independently formulated a theorem of an evolving Universe.<ref>Daintith J. Dictionary Of Scientists [e-book]. Oxford University Press; 1999. Available from: eBook Collection (EBSCOhost), Ipswich, MA. Accessed October 18, 2012.</ref>

In June 1925 Friedmann was appointed as director of the Main Geophysical Observatory in Leningrad. In July 1925 he participated in a record-setting balloon flight, reaching an elevation of {{convert|7400|m|ft|abbr=on}}.<ref name="Davidson">Davidson et al., ''A Voyage Through Turbulence'', Cambridge University Press, {{ISBN|9780521149310}}, September 2011 (for a partial and legal <!-- from one of the contributors pages --> excerpt of the book, see: [http://www.weizmann.ac.il/home/fnfal/papers/FalkovichRussians.pdf])</ref>

==Work==
Friedmann's 1924 papers, including "{{lang|de|Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes}}" ("On the possibility of a world with constant negative curvature of space") published by the German physics journal ''[[Zeitschrift für Physik]]'' (Vol. 21, pp.&nbsp;326–332), demonstrated that he had command of all three Friedmann models describing positive, zero and negative curvature respectively, a decade before [[Howard Percy Robertson|Robertson]] and [[Arthur Geoffrey Walker|Walker]] published their analysis.{{cn|date=November 2022}}

This dynamic [[physical cosmology|cosmological]] model of [[general relativity]] would come to form the standard for both the [[Big Bang]] and [[Steady State theory|Steady State]] theories. Friedmann's work supported both theories equally, so it was not until the detection of the [[cosmic microwave background radiation]] that the Steady State theory was abandoned in favor of the current favorite Big Bang paradigm.{{cn|date=November 2022}}

The classic [[Riemannian metric|solution]] of the Einstein field equations that describes a homogeneous and isotropic universe was called the [[Friedmann–Lemaître–Robertson–Walker metric]], or ''FLRW'', after Friedmann, [[Georges Lemaître]], [[Howard P. Robertson]] and [[Arthur Geoffrey Walker]], who worked on the problem in the 1920s and 30s independently of Friedmann.{{cn|date=November 2022}}

In addition to general relativity, Friedmann's interests included [[hydrodynamics]] and [[meteorology]].

Physicists [[George Gamow]], [[Vladimir Fock]], and Lev Vasilievich Keller<ref name="Davidson"/> were among his students.

==Personal life and death==
[[File:А. А. Фридман..jpg|thumb|Friedmann's grave at [[Smolensky Cemetery]], [[Saint-Petersburg]]]]
In 1911, he married Ekaterina Dorofeeva, though he later divorced her. He married Natalia Malinina in 1923. They had a religious wedding ceremony, though both were far from religious.<ref>{{cite book|title=Alexander A Friedmann: The Man who Made the Universe Expand|date=2006|publisher=[[Cambridge University Press]]|isbn=9780521025881|chapter=The final year|page=209|author=Eduard A. Tropp|author2=Viktor Ya. Frenkel|author3=Artur D. Chernin|quote=[Alexander Friedmann and Natalia Malinina] even had a religious wedding ceremony in the Crimea, though both were far from religious. “Just to make it stronger,” Friedmann said to his wife (she told this to her sister Sofia).}}</ref> They had a son Alexander Alexandrovich Friedman (1925—1983), born after his father's death.

Friedmann died on September 16, 1925, from misdiagnosed [[typhoid fever]]. He had allegedly contracted the bacteria on return from his honeymoon in [[Crimea]], when he ate an unwashed pear bought at a railway station.<ref>{{Cite journal|last=Френкель|first=Виктор Яковлевич|date=1988-07-01|title=Александр Александрович Фридман (Биографический очерк)|url=https://ufn.ru/ru/articles/1988/7/d/|journal=Успехи физических наук|language=ru|volume=155|issue=7|pages=481–516|issn=0042-1294}}</ref>

==Legacy==
The Moon crater [[Fridman (crater)|Fridman]] is named after him.<ref>{{Cite journal|last=Menzel|first=D. H.|date=1971|title=Report on Lunar Nomenclature by The Working Group of Commission 17 of the IAU|url=http://adsabs.harvard.edu/full/1971SSRv...12..136M|journal=Space Science Reviews|language=en|volume=12|issue=2|pages=136–186|doi=10.1007/BF00171763|bibcode=1971SSRv...12..136M|s2cid=122125855}}</ref>

Alexander Friedmann International Seminar is a periodical scientific event. The objective of the meeting is to promote contact between scientists working in the field of Relativity, Gravitation and Cosmology, and related fields. The First Alexander Friedmann International Seminar on Gravitation and Cosmology devoted to the centenary of his birth took place in 1988.

During the [[2022 COVID-19 protests in China]], [[Tsinghua University]] students were seen displaying Friedmann's equation as if it were a protest slogan, which was understood as an [[Censorship in China#Circumventing_censorship|evasion of censorship]] by punning multilingually on "free man" and referring to liberalization and opening via the expansion of the universe.<ref>{{cite web | url=https://www.vice.com/en/article/china-zero-covid-protest-signs/ | title=Why Are Students Holding up This Physics Equation During China's COVID Protests? | date=28 November 2022 }}</ref>

==Selected publications==
*{{cite journal|last=Friedman|first=A.|date=1922|title=Über die Krümmung des Raumes |journal=Zeitschrift für Physik|volume=10|issue=1|pages=377–386|doi=10.1007/BF01332580|bibcode=1922ZPhy...10..377F|s2cid=125190902}}. English translation in: {{Cite journal| first1 = A.| title = On the curvature of space | journal = General Relativity and Gravitation | volume = 31| issue = 12| last1 = Friedman | pages = 1991–2000 | date = 1999 | doi = 10.1023/A:1026751225741| bibcode=1999GReGr..31.1991F| s2cid = 122950995 }} The original Russian manuscript of this paper is preserved in the [http://ilorentz.org/history/Friedmann_archive Ehrenfest archive], together with some letters and unpublished work.
*{{cite journal|last=Friedman|first=A.|date=1924|title=Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes|journal=Zeitschrift für Physik|volume=21|issue=1|pages=326–332 |doi=10.1007/BF01328280|bibcode=1924ZPhy...21..326F|s2cid=120551579}}. English translation in: {{Cite journal| first1 = A.| title = On the Possibility of a World with Constant Negative Curvature of Space| journal = General Relativity and Gravitation| volume = 31| issue = 12| last1 = Friedmann| pages = 2001–2008| date = 1999| doi = 10.1023/A:1026755309811| bibcode=1999GReGr..31.2001F| s2cid = 123512351}}

==References==
{{Reflist}}

==Bibliography==
*{{cite journal|author=Poluboyarinova-Kochina, P. Ya.|date=January–February 1964|title=Aleksandr Fridman|url= http://www.iop.org/EJ/article/0038-5670/6/4/E01/PHU_6_4_E01.pdf?request-id=7429cf76-2dd8-4055-87c8-fa001c02acd1 |journal=Soviet Physics Uspekhi (English Edition)|pages=467–472}}
*{{cite book|title=Stephen Hawking: Quest For A Theory of Everything|last=Ferguson|first=Kitty|date=1991|publisher=[[Bantam Books]]|location=New York|isbn=0-553-29895-X|url-access=registration|url=https://archive.org/details/stephenhawking00kitt}}
*{{cite journal|journal=Soviet Physics Uspekhi|volume=31|issue=7|first=V.Ya.|last=Frenkel'|date=1988|pages=645–665|doi=10.1070/PU1988v031n07ABEH003574|title=Aleksandr Aleksandrovich Fridman (Friedmann): a biographical essay|bibcode=1988SvPhU..31..645F}}

==External links==
*[https://books.google.com/books?id=mSt2uH5BizMC  ''Alexander A Friedmann: The Man who Made the Universe Expand'' – Biography written by Eduard A. Tropp, Viktor Ya. Frenkel and Artur D. Chernin]
*{{MacTutor Biography|id=Friedmann}}
*[https://books.google.com/books?id=hvKzeJouZ9UC&pg=PA16 ''How Do We Know the Age of the Universe'' – Mary Lynn Germadnik]

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[[Category:1888 births]]
[[Category:1925 deaths]]
[[Category:Soviet mathematicians]]
[[Category:20th-century Russian mathematicians]]
[[Category:Russian relativity theorists]]
[[Category:Jewish Soviet physicists]]
[[Category:Scientists from Saint Petersburg]]
[[Category:Pennsylvania State University faculty]]
[[Category:Russian people of Jewish descent]]
[[Category:Russian people of Czech descent]]
[[Category:Recipients of the Lenin Prize]]
[[Category:Russian scientists]]