It is out of the question. It must be dark in the ancient tomb. Even if the light is on when the underground is closed, the light will definitely go out when all the oxygen in it is burned out. But according to the record, there is indeed a record that the light is on when the underground is turned on, but it can't be on all the time. It should be to open the underground and let oxygen in, which will lead to the light rekindling!
Even some other substances, such as whale oil or white phosphorus, can burn for a long time, but once the oxygen is used up, it will go out. Therefore, the ever-burning lamp that lasts for thousands of years basically does not exist!
However, why do ancient records show that lanterns are always on? The reason is that the cognitive level in ancient times was relatively low. There is a substance in chemistry called white phosphorus. After the underground palace is opened, oxygen enters, and white phosphorus will spontaneously ignite, causing lanterns to ignite. The Millennium ever-burning lamp in the ancient tomb is just a legend. No one has ever seen it, but it did burn for a long time. There is a folk proverb in China. The ever-burning lamp in Qin Shihuang's tomb is refined from human fish oil, which is also a legend. Don't believe it.
This kind of lamp is mostly used in Buddhist temples and temples. It was also recorded in ancient times that during the New Year's Eve, gods went to heaven and ghosts would go out for food. If you turn off the lights, you will catch people in the dark, such as children crying and old people coughing. Of course, this is also fiction!