※ 引述《ftes90049 (我勒个去)》之铭言：
: 因果论也不再有意义
: 那在数十亿年后 仙女座星系要跟银河系碰撞
: 会成为人类的大危机吗?
星系碰撞在宇宙是相当普遍的。例如一般认为仙女座星系在过去就曾经和其他星系至少发
生过一次碰撞。理论上我们的太阳系在这场碰撞过程中也有一定的可能从合并形成的新星
系中释放出来，而在星系碰撞的初期甚至有可能成为仙女座星系的一部分。由于恒星间的
距离非常遥远，这种事件对太阳系本身不会有什么负面影响。
http://i.imgur.com/PmUwil4.jpg
Cosmos:A Spacetime Odyssey S01E03
Neil deGrasse Tyson: Using nothing more than Newton's laws of gravitation,
we astronomers can confidently that several billion years from now,our home
galaxy, the Milky Way, will merge with our neighboring galaxy Andromeda.
Because the distances between the stars are so great compared to their sizes,
few if any stars in either galaxy will actually collide. Any life on the worlds
of that far-off future should be safe, but they would be treated to an amazing,
billion-year-long light show...a dance of a half a trillion stars...