1979年諾貝爾獎得主、美國物理學家謝爾登·格拉肖(Sheldon Lee Glashow)是超弦理論的懷疑者,因為其不能提供實驗可檢驗的預言。他曾經試圖阻止超弦理論家進入哈佛大學物理系,但是哈佛大學還是接受了超弦理論,於是他選擇了離開。[1] 在約十分鐘《弦論這件事》(《優雅的宇宙》第二部分)的採訪中,他認為超弦是一門與物理沒有關係的學科,並且說:「...你可以把它稱為腫瘤...」[2]。
^"there ain't no experiment that could be done nor is there any observation that could be made that would say, `You guys are wrong.' The theory is safe, permanently safe." He also said, "Is this a theory of Physics or Philosophy? I ask you" NOVA interview (頁面存檔備份,存於網際網路檔案館))