在塵埃宇宙中，不均勻性導致宇宙加速膨脹之探索

Abstract

一般認為，如果宇宙中只存在產生吸引力的物質或能量，那麼宇宙必然只會減速膨脹。為了檢驗這個概念，我們在一個用來描述球對稱的塵埃流體的精確解中(Lemaitre-Tolman-Bondi solution)，找出了反例。因此，這個概念其實是令人懷疑的。對於宇宙的不均勻性，我們應該更深入的研究。這些例子，開啟一個新的角度去了解我們宇宙的演化。

It is the common consensus that the expansion of a universe always slows down if the gravity provided by the energy sources therein is universally attractive. To examine this point we find counter-examples for the spherically symmetric dust fluid described by the Lemaitre-Tolman-Bondi solution. Thus, the validity of this naive consensus is indeed doubtful and the effects of inhomogeneities should be restudied. The example opens a new perspective for understanding the evolution of our universe.