Infinity

Long time ago, our ancestors looked up at starry sky, the vast galaxy, asked how big the world we live in was. As intelligent being, we think about ourselves, our planet, the universe, and infinity. People abstracted numbers from concrete things: from three goats, three apples, and three jars to three of anything. The numbers were not big at first, sufficient for hunting, collecting, and farming. As civilization evolved, people started to trade. A variety of numbering systems were developed to support bigger and bigger numbers. It’s natural to ask what the biggest number is. There were two different opinions in ancient time. Some didn’t think the question make sense. It’s already big enough like thousands or millions in everyday life.