Greer Garson
Marie Curie
Acting
Walter Pidgeon
Pierre Curie
Acting
Henry Travers
Eugene Curie
Acting
Albert Bassermann
Professor Jean Perot
Acting
Robert Walker
David Le Gros
Acting
C. Aubrey Smith
Lord Kelvin
Acting
May Whitty
Madame Eugene Curie
Acting
Victor Francen
President of University
Acting
Elsa Bassermann
Madame Perot
Acting
Reginald Owen
Dr. Becquerel
Acting
Van Johnson
Reporter
Acting
Margaret O'Brien
Irene Curie - Age 5
Acting
James Hilton
Narration Spoken By (voice)
Writing
Mariska Aldrich
Tall Woman (uncredited)
Acting
Tony Carson
Man at Accident (uncredited)
Acting
Ruth Cherrington
Swedish Queen (uncredited)
Acting
Ray Collins
Lecturer (voice) (uncredited)
Acting
Guy D'Ennery
Professor (uncredited)
Acting
George Davis
Cart Driver (uncredited)
Acting
Harold De Becker
Professor (uncredited)
Acting
Franz Dorfler
Assistant Tailor (uncredited)
Acting
Justine Duney
Woman at Accident (uncredited)
Acting
Tay Dunn
Man at Accident (uncredited)
Acting
William Edmunds
Cart Driver (uncredited)
Acting
Nestor Eristoff
Board Member (uncredited)
Acting
Al Ferguson
Man at Accident (uncredited)
Acting
Edward Fielding
Board Member (uncredited)
Acting
Howard Freeman
Prof. Constant (voice) (uncredited)
Acting
Linda Lee Gates
Perot Granddaughter (uncredited)
Acting
Marie Louise Gates
Perot Granddaughter (uncredited)
Acting
Lisa Golm
Lucille (uncredited)
Acting
Ilka Grüning
Seamstress (uncredited)
Acting
Lumsden Hare
Professor Roget (uncredited)
Acting
Teddy Infuhr
Son (uncredited)
Acting
James Kirkwood
Board Member (uncredited)
Acting
Isabel La Mal
Woman at Accident (uncredited)
Acting
Gene Lockhart
Bit Part (uncredited)
Acting
Miles Mander
Businessman (uncredited)
Acting
George Meader
Singing Professor (uncredited)
Acting
Dickie Meyers
Master Michaud (uncredited)
Acting
Noel Mills
Wedding Guest (uncredited)
Acting
Leo Mostovoy
Photographer (uncredited)
Acting
Alan Napier
Dr. Bladh (uncredited)
Acting
Moroni Olsen
President of Businessman's Board (uncredited)
Acting
María Pagés
Woman at Accident (uncredited)
Acting
Gigi Perreau
Eve at 18 Months (uncredited)
Acting
Francis Pierlot
Monsieur Michaud (uncredited)
Acting
Nita Pike
Woman at Accident (uncredited)
Acting
Dorothy Raye
Nurse (uncredited)
Acting
Almira Sessions
Madame Michaud (uncredited)
Acting
Arthur Shields
Businessman (uncredited)
Acting
Wyndham Standing
King Oscar (uncredited)
Acting
Ray Teal
Driver (uncredited)
Acting
Charles Trowbridge
Board Member (uncredited)
Acting
Michael Visaroff
Proud Papa (uncredited)
Acting
Marek Windheim
Jewelry Salesman (uncredited)
Acting
Frederick Worlock
Businessman (uncredited)
Acting
Eustace Wyatt
Doctor (uncredited)
Acting