121 years ago today, on November 16, 1904 (October 10, 1904 in the lunar calendar), John Ambrose Fleming invented the vacuum tube. The history of vacuum tubes can be traced back to Thomas Alva Edison, the inventor of the light bulb. One day in 1880, he curiously placed an extra electrode in the light bulb and sprinkled some foil. As a result, he discovered a strange phenomenon: when the third pole was positively charged, the foil did not respond; but when the third pole was negatively charged, the foil immediately rolled and floated. Edison did not know the cause of this phenomenon at the time, but due to his inadvertent discovery, this phenomenon was later called the Edison Effect. It was not until 1901 that Owen Richardson proposed a law stating that the excited state of electrons caused the foil to float, and later won the 1928 Nobel Prize in Physics. Then John Ambrose Fleming developed the diode in 1904, and Lee DeForest made the first transistor in 1907.