黃偉彥臺灣大學：物理研究所莊家勛Chuang, Chia-HsunChia-HsunChuang2007-11-262018-06-282007-11-262018-06-282006http://ntur.lib.ntu.edu.tw//handle/246246/54572一般認為，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.1 Introduction 7 2 De‾nitions of Acceleration 11 2.1 Define Line Acceleration. . . . . . . . . . .11 2.2 Define Domain Acceleration . . . . . . . . .12 2.3 The Constraint of the Domain Acceleration . .13 3 Lemaitre-Tolman-Bondi (LTB) Solution 17 3.1 Basic of the LTB solution . . . . . . . . . .17 3.2 Constraints for the LTB Solution . . . . . . 19 4 Line Acceleration induced by Inhomogeneities . 21 4.1 When E(r) is a Constant . . . . . . . . . . .22 4.2 When E(r) is not a Constant . . . . . . . . .22 5 Domain Acceleration induced by Inhomogeneities 27 5.1 Domain Acceleration with tb(r) = 0 . . . . . 27 5.1.1 Previous Example . . . . . . . . . . . . . 27 5.1.2 Showing the Previous Example is Wrong . . .29 5.2 Domain Acceleration with tb(r) 6= 0 . . . . .30 6 Summary and Prospect 39478466 bytesapplication/pdfen-US不均勻黑暗能量加速膨脹inhomogeneityinhomogeneitiesdark energycosmic accelerationthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54572/1/ntu-95-R92222016-1.pdf