15 episode, how many Edison does it take to twist a light bulb? What does that joke mean?

Sheng is a world-famous inventor. He is an American. When I was a child, I only went to school for three months because my family was poor. He started selling newspapers at the age of eleven or twelve. He loves science and often saves money to buy science books, newspapers and chemicals. His experimental tools are bottles and cans picked out of garbage. When Edison 12 years old, he sold newspapers on the train. There is a special compartment on the train for passengers to smoke. The conductor agreed that he would occupy a corner there. He moved all the chemicals and bottles and cans there. After selling the newspaper, he did all kinds of interesting experiments. Once, when the train started, it suddenly shook and knocked down a bottle of white phosphorus. When phosphorus comes into contact with air, it burns immediately. Many people came to put out the fire with Edison. The conductor was so angry that he threw all Edison's experiments out and gave him a good beating. Deaf his ears. Edison's determination to study science has not wavered. He scrimped and saved, and started his chemical experiment again. Once, sulfuric acid burned his clothes. On another occasion, nitric acid almost blinded his eyes. He was not frightened by the danger, but he still stubbornly carried out the experiment. Edison tried to make an electric lamp. In order to find a filament with low price and long service life, he did many experiments. He often works in the laboratory for dozens of hours, so he is too tired to lie on the experimental platform and sleep for a while. He worked tirelessly and finally found a suitable filament and invented the electric light. Later,