早期宇宙學研究中，認為宇宙的組成為一般物質與輻射。然而1998年，SNIa觀測結果顯示：宇宙正在加速膨脹。由於只有一般物質與輻射的宇宙並不會加速膨脹，為解釋此現象，科學家引入Λ-CDM模型。但此模型雖解釋了宇宙加速膨脹，卻有宇宙常數問題。為避免使用宇宙常數，科學家轉往嘗試其他模型；本研究將重點置於f(R)重力理論的宇宙演化中。

由於f(R)重力理論的宇宙早期演化與廣義相對論十分接近，故人們以廣義相對論宇宙早期演化的行為作為此模型早期行為的近似。本研究修改CAMB程式，由宇宙極早期開始演算f(R)重力理論的宇宙演化，比較其與廣義相對論計算所得的差異，推論先前人們的近似法是否合理。

本研究測試f(R)設計者模型與其餘四種f(R)模型，發現對於一新的f(R)模型，其與廣義相對論演算所得的差異在紅移z=65之後可能大於10^{-3}。故以廣義相對論早期的演化作為f(R)重力理論宇宙早期行為的近似一法，最晚只可用到z=65，晚於此時間，f(R)重力理論宇宙的演化與廣義相對論的差異將不可忽略。

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