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{{Short description|American physicist (1881–1948)}}
{{Infobox scientist
| name              = Richard C. Tolman
| image             = Richard C. Tolman.jpg
| caption           = {{longitem|Richard C. Tolman in 1945}}
| birth_date        = {{birth date|1881|3|4|mf=yes}}
| birth_place       = West Newton, Massachusetts, U.S.
| death_date        = {{death date and age|1948|9|5|1881|3|4|mf=yes}}
| death_place       = Pasadena, California, U.S.
| doctoral_students = [[Allan C. G. Mitchell]] <br/> [[Linus Pauling]]
| alma_mater        = [[Massachusetts Institute of Technology]] ([[B. S.|BS]], [[PhD]])
| workplaces        = California Institute of Technology
| doctoral_advisor  = [[Arthur Amos Noyes]]
| fields            = Physical chemistry <br/> Statistical Mechanics <br/> Cosmology
| thesis_title      = The Electromotive Force Produced in Solutions by Centrifugal Action
| thesis_year       = 1910
| thesis_url        = https://mit.primo.exlibrisgroup.com/permalink/01MIT_INST/ejdckj/alma990008427050106761
}}

'''Richard Chace Tolman''' (March 4, 1881&nbsp;– September 5, 1948) was an American [[Mathematical physics|mathematical physicist]] and [[physical chemist]] who made many contributions to [[statistical mechanics]] and [[Physical cosmology|theoretical cosmology]].<ref>{{Citation |last=Gale |first=George |title=Tolman, Richard Chace |date=2014 |pages=2164–2165 |place=New York, NY |publisher=Springer New York |bibcode=2014bea..book.2164G |doi=10.1007/978-1-4419-9917-7_1388 |isbn=978-1-4419-9916-0 |encyclopedia=Biographical Encyclopedia of Astronomers}}</ref> He was a professor at the [[California Institute of Technology]] (Caltech).<ref name=":0">{{Cite journal |last1=Kirkwood |first1=John A. |last2=Wulf |first2=Oliver R. |last3=Epstein |first3=P. S. |date=1952 |title=Richard Chace Tolman |url=https://www.nasonline.org/wp-content/uploads/2024/06/tolman-richard.pdf |journal=Biographical Memoir |publisher=National Academy of Sciences (NAS) |pages=139–153}}</ref>

== Early life and education ==
{{Cosmology}}Tolman was born in [[West Newton, Massachusetts]] to a successful businessman and a Quaker mother. Tolman attended the local public schools before matriculating at the [[Massachusetts Institute of Technology]] (MIT), where he earned his [[bachelor's degree]] in [[chemical engineering]] 1903.<ref name=":0" /> He spent the following year studying abroad in Germany before returning to MIT for further studies. He was mentored by [[Arthur Amos Noyes]], a pioneer of physical chemistry, and received PhD in 1910 under Noyes' supervision.<ref>{{MathGenealogy|id=138428}}</ref> He subsequently worked briefly at various universities before the outbreak of World War I.<ref name=":0" />

== Scientific career ==
In 1912, he conceived of the concept of [[relativistic mass]], writing that "the expression <math>m_0 \left(1 - \frac{v^2}{c^2} \right)^{-1/2}</math> is best suited for the mass of a moving body."<ref>{{cite journal|author=Tolman, R. C.|year=1912|title= Non-Newtonian Mechanics, The Mass of a Moving Body|journal=Philosophical Magazine|volume=23|issue=135|pages=375–381|url=https://archive.org/stream/londonedinburg6231912lond#page/374/mode/2up/search/tolman|doi=10.1080/14786440308637231}}</ref>

During the First World War, Tolman served in the Chemical Warfare Service, attaining the rank of Major. When the war ended, he continued working for the government for some years, researching [[nitrogen fixation]].<ref name=":0" />

In a 1916 experiment with [[Thomas Dale Stewart]], Tolman demonstrated that electricity consists of [[electron]]s flowing through a metallic [[Electrical conductor|conductor]]. A by-product of this experiment was a measured value of the [[Electron mass|mass of the electron]].<ref>{{cite journal|author=Tolman, R. C.|author2=Stewart, T. D.|title=The electromotive force produced by the acceleration of metals|journal=Physical Review|volume=8|issue=2|year=1916|pages=97–116|doi=10.1103/PhysRev.8.97|pmid=16576140|bibcode=1916PhRv....8...97T|url=https://babel.hathitrust.org/cgi/pt?id=pst.000050421268;view=1up;seq=115|pmc=1090978|hdl=2027/uc1.c3529756}}</ref><ref name=":0" /> This early work sparked Tolman's interest in [[chemical kinetics]] and statistical mechanics.<ref name=":0" /> Tolman and his collaborators at the Fixed Nitrogen Research Laboratory at the University of California thanked the government for enabling them to conduct fundamental research that had little immediate relevance to their assigned project, writing that "such a liberal policy is of great importance in maintaining a proper scientific attitude on the part of the staff of a research laboratory."<ref name=":0" />

Tolman was a member of the [[Technical Alliance]] in 1919, a forerunner of the [[Technocracy movement]] where he helped conduct an energy survey analyzing the possibility of applying science to social and industrial affairs.<ref>{{cite web |url=http://www.technocracy.org/technical-alliancetn/the-beginning/241-waringscheel |title=The Technical Alliance Profiles |access-date=2013-03-16 |url-status=dead |archive-url=https://web.archive.org/web/20121221195448/http://www.technocracy.org/technical-alliancetn/the-beginning/241-waringscheel |archive-date=2012-12-21 }} Retrieved March-16-13</ref><ref>{{cite book|author=Anderson, Larry|title=Benton MacKaye: Conservationist, planner, and creator of the Appalachian Trail|publisher=JHU Press|year=2002|page=136|url=https://books.google.com/books?id=I1hayhB0DEYC&pg=PA136|access-date=12 July 2013|isbn=9780801869020}}</ref><ref>{{cite book|author=Anderson, Larry|title=Benton MacKaye: Conservationist, planner, and creator of the Appalachian Trail|publisher=JHU Press|year=2002|page=48|url=https://books.google.com/books?id=pQxy2PRHWrwC&pg=PA48|access-date=13 July 2013|isbn=9780226465838}}</ref>

[[File:Richard C. Tolman and Albert Einstein at California Institute of Technology.jpg|thumb|Richard C. Tolman and [[Albert Einstein]] at Caltech, Pasadena, 1932]]

Tolman was elected a Fellow of the [[American Academy of Arts and Sciences]] in 1922.<ref name=AAAS>{{cite web |title=Book of Members, 1780-2010: Chapter T |url=http://www.amacad.org/publications/BookofMembers/ChapterT.pdf |publisher=[[American Academy of Arts and Sciences]] |access-date=20 April 2011}}</ref> The same year, he joined the faculty of the California Institute of Technology, where he became professor of physical chemistry and mathematical physics and later Dean of Graduate Studies.<ref name=":0" /> One of Tolman's early students at Caltech was the theoretical chemist [[Linus Pauling]], to whom Tolman taught the [[old quantum theory]]. Tolman was elected to the [[National Academy of Sciences]] of the United States in 1923.<ref>{{Cite web |title=Richard C. Tolman |url=http://www.nasonline.org/member-directory/deceased-members/20001648.html |access-date=June 28, 2023 |website=National Academy of Science of the United States (NAS)}}</ref> His years at Caltech were his most productive.<ref name=":0" />

In 1927, Tolman published a text on statistical mechanics whose background was the old quantum theory of [[Max Planck]], [[Niels Bohr]] and [[Arnold Sommerfeld]].<ref>{{cite journal|author=Bartky, W.|author-link=Walter Bartky|title=Review: ''Statistical Mechanics with Applications to Physics and Chemistry'' by Richard C. Tolman|journal=Astrophysical Journal|year=1927|volume=66|pages=143–144|bibcode=1927ApJ....66..143B|doi=10.1086/143076}}</ref> Tolman was elected to the [[American Philosophical Society]] in 1932.<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Richard+C.+Tolman&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-06-28 |website=search.amphilsoc.org}}</ref> In 1938, he published a new detailed work that covered the application of statistical mechanics to [[Classical physics|classical]] and [[quantum system]]s.<ref>{{cite journal|author=Sterne, Theodore E.|journal=Astrophysical Journal|title=Review: ''The Principles of Statistical Mechanics'' by Richard C. Tolman|year=1941|volume=93|page=513|bibcode=1941ApJ....93..513.|doi=10.1086/144301|doi-access=free}}</ref><ref>{{cite journal|author=Infeld, L.|author-link=Leopold Infeld|title=Review: ''The Principles of Statistical Mechanics'' by Richard C. Tolman|journal=Philosophy of Science|date=July 1939|volume=6|issue=3|page=381|doi=10.1086/286579}}</ref> In his work on the subject, Tolman built heavily upon the key contributions of [[Ludwig Boltzmann]], [[Josiah Willard Gibbs|J. Willard Gibbs]], [[Paul Ehrenfest|Paul]] and [[Tatyana Afanasyeva|Tatyana Ehrenfest]].<ref name=":0" />

Tolman took an interest in [[general relativity]]. He researched the application of [[thermodynamics]] to [[Relativity theory|relativistic systems]] and [[cosmology]]. He established a number of theoretical results important in the study of an expanding universe.<ref name=":0" /> In his 1934 [[monograph]] titled ''Relativity, Thermodynamics, and Cosmology,''<ref>{{cite journal|author=Chant, C. A.|author-link=Clarence Chant|journal=Journal of the Royal Astronomical Society of Canada|year=1934|volume=28|pages=324–325|title=Review: ''Relativity, Thermodynamics, and Cosmology'' by Richard C. Tolman|bibcode=1934JRASC..28Q.324C}}</ref> Tolman demonstrated how [[black body]] radiation in an expanding universe cools but remains [[Thermal radiation|thermal]]{{spaced ndash}}a key pointer toward the properties of the [[cosmic microwave background]].<ref name=Reynosa>{{cite web|last1=Reynosa|first1=Peter|title=Why Isn't Edward P. Tryon A World-famous Physicist?|url=http://www.huffingtonpost.com/peter-reynosa/why-isnt-edward-p-tryon-world-famous_b_9471504.html|publisher=Huffington Post|access-date=March 22, 2016|date=2016-03-16}} (See [[Edward Tryon]].)</ref> Also in this monograph, Tolman was the first person to document and explain how a closed universe could equal zero energy. He explained how all mass energy is positive and all gravitational energy is negative and they cancel each other out, leading to a universe of zero energy.<ref name=Reynosa/> His investigation of the [[oscillatory universe]] hypothesis, which [[Alexander Friedmann]] had proposed in 1922, drew attention to difficulties as regards [[entropy]] and resulted in its demise until the late 1960s. Tolman interpreted astronomical observations in terms of the new cosmology in collaboration with [[Edwin Hubble]].<ref name=":0" />

During the 1930s, Tolman obtained solutions to the [[Einstein field equations]] describing the [[static spherically symmetric perfect fluid]].<ref>{{cite journal |last=Tolman |first=R. C. |date=1934 |title=Effect of Inhomogeneity on Cosmological Models |url=http://authors.library.caltech.edu/9466/1/TOLpnas34c.pdf |journal=[[Proceedings of the National Academy of Sciences]] |volume=20 |issue=3 |pages=169–176 |bibcode=1934PNAS...20..169T |doi=10.1073/pnas.20.3.169 |pmc=1076370 |pmid=16587869 |doi-access=free}}</ref><ref>{{Cite journal |last=Tolman |first=Richard C. |date=1939 |title=Static Solutions of Einstein's Field Equations for Spheres of Fluid |url=https://journals.aps.org/pr/abstract/10.1103/PhysRev.55.364 |journal=Physical Review |volume=55 |issue=364 |pages=364–373 |bibcode=1939PhRv...55..364T |doi=10.1103/PhysRev.55.364}}</ref> [[J. Robert Oppenheimer]], [[Robert Serber]], and [[George Volkoff]], built upon this work in their investigation the stability of [[Neutron star|neutron stars]], obtaining the [[Tolman–Oppenheimer–Volkoff limit|Tolman-Oppenheimer-Volkoff limit]].<ref>{{cite journal |last1=Oppenheimer |first1=J.R. |last2=Serber |first2=Robert |author-link2=Robert Serber |year=1938 |title=On the Stability of Stellar Neutron Cores |journal=[[Physical Review]] |volume=54 |issue=7 |pages=540 |bibcode=1938PhRv...54..540O |doi=10.1103/PhysRev.54.540}}</ref><ref>{{cite journal |last1=Oppenheimer |first1=J.R. |last2=Volkoff |first2=G.M. |author-link2=George Volkoff |year=1939 |title=On Massive Neutron Cores |url=http://www.mpia-hd.mpg.de/home/fendt/Lehre/Vorlesung_CO/1939_oppenheimer_volkoff.pdf |url-status=live |journal=[[Physical Review]] |volume=55 |issue=4 |pages=374–381 |bibcode=1939PhRv...55..374O |doi=10.1103/PhysRev.55.374 |archive-url=https://web.archive.org/web/20140116084323/http://www.mpia-hd.mpg.de/home/fendt/Lehre/Vorlesung_CO/1939_oppenheimer_volkoff.pdf |archive-date=January 16, 2014 |access-date=January 15, 2014}}</ref>

During [[World War II]], Tolman served as scientific advisor to General [[Leslie Groves]] on the [[Manhattan Project]].<ref name=":0" /> At the time of his death in [[Pasadena, California|Pasadena]], he was chief advisor to [[Bernard Baruch]], the U.S. representative to the [[United Nations Atomic Energy Commission]].

He resumed civilian life in 1947 and published some papers on the thermodynamics of surface phases. He died on September 5, 1948, three weeks after suffering a [[cerebral hemorrhage]] without warning.<ref name=":0" />

Each year, the [[southern California]] section of the [[American Chemical Society]] honors Tolman by awarding its [[Tolman Award|Tolman Medal]] "in recognition of outstanding contributions to chemistry."

== Family ==

Tolman's brother was the [[Behaviorism|behavioral psychologist]] [[Edward Chace Tolman]]. He married psychologist [[Ruth Sherman Tolman]] in 1924.<ref name=":0" />

== See also ==
{{Portal|Biography|Physics}}
*[[List of textbooks in thermodynamics and statistical mechanics]]
* [[Tolman length]]
* [[Tolman surface brightness test]]
* [[Tachyonic antitelephone|Tolman's paradox]]
* [[H-theorem#Tolman's H-theorem|Tolman's H theorem]]
* [[Ehrenfest–Tolman effect|Tolman–Ehrenfest effect]]
* [[Tolman–Oppenheimer–Volkoff equation]]
* [[Lemaître–Tolman metric]]
* [[Trouton–Noble experiment#Right-angle lever paradox|Lewis–Tolman paradox]]
* [[Stewart–Tolman effect]]
* [[Oscillatory universe]]
* [[Thin Man (nuclear bomb)]]

== References ==
{{Reflist|30em}}

==Books by Tolman==
{{wikisource author}}
* {{cite book |title=Statistical mechanics with applications to physics and chemistry |url=https://archive.org/details/statisticalmecha00tolm |year=1927 |location=New York |publisher=The Chemical Catalog Company}}
* {{cite book |title=Relativity, Thermodynamics, and Cosmology |url=https://archive.org/details/in.ernet.dli.2015.177229 |location=Oxford |publisher=Clarendon Press |year=1934 |lccn=34032023 }} Reissued (1987) New York: Dover {{ISBN|0-486-65383-8}}.
* {{cite book |title=The Principles of Statistical Mechanics |publisher=Clarendon Press |year=1938 |location=Oxford |url=https://books.google.com/books?id=4TqQZo962s0C|isbn=9780486638966 }} Reissued (1979) New York: Dover {{ISBN|0-486-63896-0}}. {{cite book|title=1987 Dover reprint|url=https://books.google.com/books?id=kIcWAktlk7cC|isbn = 9780486653839|last1 = Tolman|first1 = Richard Chace|date = January 1987| publisher=Courier Corporation }}
<gallery>
File:Tolman-1.jpg|''Relativity, Thermodynamics and Cosmology'' (1934)
File:Tolman-4.jpg|Table of contents to ''Relativity, Thermodynamics and Cosmology'' (1934)
File:Tolman-5.jpg|Introduction to ''Relativity, Thermodynamics and Cosmology'' (1934)
</gallery>

== External links ==
* [http://content.cdlib.org/view?docId=tf4w1003fs&chunk.id=bioghist-1.7.3 Short biography] from the Online Archive of California
* [http://scalacs.org/?page_id=20 Short biography] from the "Tolman Award" page of the Southern California Section of the American Chemical Society.
* {{Gutenberg author | id=36080}}
* {{Internet Archive author |sname=Richard Chace Tolman}}
* [https://www.nasonline.org/wp-content/uploads/2024/06/tolman-richard.pdf Biographical memoir], National Academy of Sciences. Includes a complete bibliography of Tolman's writings. Retrieved October 4, 2024.

{{Special relativity|people}}
{{Authority control}}

{{DEFAULTSORT:Tolman, Richard Chace}}
[[Category:1881 births]]
[[Category:1948 deaths]]
[[Category:20th-century American physicists]]
[[Category:California Institute of Technology faculty]]
[[Category:American cosmologists]]
[[Category:Fellows of the American Academy of Arts and Sciences]]
[[Category:Manhattan Project people]]
[[Category:MIT School of Engineering alumni]]
[[Category:Scientists from Newton, Massachusetts]]
[[Category:American relativity theorists]]
[[Category:American physical chemists]]
[[Category:20th-century American chemists]]
[[Category:Members of the American Philosophical Society]]