The expansion of the universe is like Darwinian evolution in another curious way: most scientists think they understand it, but few agree on what it really means.

• 宇宙的膨胀和达尔文的演化论，还有著另一个古怪的相似处：大部份科学家都认为他们了解这个理论，可是对其真正的涵义，却很少意见一致。