https://www.cambridge.org/core/resources/the-cosmos-5
We have found strong evidence that what we thought was “empty space” actually contains a dark, gravitationally repulsive kind of energy that is causing the Universe to expand faster and faster with time. The origin of this “dark energy” is a complete mystery, but an understanding of it may revolutionize physics. (Chap 1)
Negativity 是否等同暗能量？
Astronomers have deduced that the Universe began almost 14 billion years ago. Let us consider that the time between the origin of the Universe and the year 2019, or 14 billion years, is compressed into one day. If the Universe began at midnight, then it wasn’t until slightly after 4 p.m. that Earth formed; the first fossils date from 6 p.m. The first humans appeared only 2 seconds ago, and it is only 1/300 second since Columbus landed in America. (Chap 1)
宇宙的一天 vs 你我的一天，所謂 have a nice day ，
Repeatedly in this book, we will discuss ways of measuring distance.
… some of the most exciting investigations of modern astronomy are related to the determination of distance. (Chap 1)
