Rịba ama amaokwu a dị n'okpuru ma zaa ajụjụ ahụ mgbe e mesịrị n'otu asụsụ ahụ dị ka amaokwu ahụ:  N'elu ndụmọdụ na nkwanye nke G. I. Taylor, Dyson kwagara United States na 1947 dị ka onye Commonwealth Fellow iji nweta doctorate physics na Hans Bethe na Mahadum Cornell (1947<unk>48). Ọ bụ n'ebe ahụ ka ọ matara Richard Feynman. Ọkà mmụta sayensị Bekee ahụ na-eto eto matara amamihe nke onye America ahụ na-egbukepụ egbukepụ, ma tinye onwe ya ngwa ngwa o kwere mee. Mgbe ahụ, ọ kwagara na Institute for Advanced Study (1948<unk>49), tupu ọ laghachi England (1949<unk>51), ebe ọ bụ onye ọrụ nyocha na Mahadum Birmingham. Na 1949 Dyson gosipụtara nha anya nke usoro abụọ nke quantum electrodynamics (QED): eserese Richard Feynman na usoro onye ọrụ nke Julian Schwinger na Shin'ichirō Tomonaga mepụtara. Ọ bụ onye mbụ mgbe onye okike ha ghọtara ike nke eserese Feynman na akwụkwọ ya edere na 1948 ma bipụtara na 1949 bụ onye mbụ jiri ha. O kwuru n'akwụkwọ ahụ na eserese Feynman abụghị naanị ngwá ọrụ mgbakọ na mwepụ kama ọ bụ usoro sayensị ma mepụta iwu maka eserese ndị na-edozi nsogbu nke renormalization kpamkpam. Akwụkwọ Dyson na nkuzi ya gosipụtara echiche Feynman banyere QED n'ụdị nke ndị ọkà mmụta sayensị ndị ọzọ nwere ike ịghọta, na-eme ka ndị obodo physics nabata ọrụ Feynman. J. Robert Oppenheimer, karịsịa, Dyson mere ka o kweta na echiche ọhụrụ Feynman bụ nke ziri ezi dị ka nke Schwinger na Tomonaga. Oppenheimer kwụghachiri Dyson ụgwọ site na nhọpụta ndụ na Institute for Advanced Study, "maka igosi m na ezighi ezi", n'okwu Oppenheimer. Ọzọkwa na 1949, na ọrụ metụtara ya, Dyson mepụtara usoro Dyson. Ọ bụ akwụkwọ a kpaliri John Ward ị nweta njirimara Ward <unk> Takahashi ya a ma ama. N'afọ 1951 Dyson sonyeere ngalaba na Cornell dị ka prọfesọ physics, ọ bụ ezie na ọ nweghị doctorate, na 1953 ọ natara ọkwa na-adịgide adịgide na Institute for Advanced Study na Princeton, New Jersey, ebe ọ nọgidere. Na 1957, ọ ghọrọ nwa amaala United States ma jụ ịbụ onye Britain....  Ajụjụ: Gịnị bụ aha ọrụ ahụ Dyson rụrụ ọrụ na ya?
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