The World in the Landscaping Box

Zhang Fan received a magical landscaping box. There is a courtyard in the box that is exactly the same as his home, and there is a little person inside, who is actually himself. He can move around freely and go out to retrieve some items from time to time. As for where to look, Zhang Fan had no idea because his sight was limited to the courtyard. After observing for several days, Zhang Fan took out a grape from it on a whim and was almost crushed to death by the grape. It turns out that a grape, which is only one millionth the size of reality, is instantly enlarged a trillion times. It turned into a huge grape grain with a diameter of 1.5 Meters and a length of 2.5 Meters. Zhang Fan got up and saw the huge grape towering in his bedroom, and was stunned for a moment. What is the principle? Waiting online, it's urgent!