Why do maids appear on the wall?

This is because the walls of the Forbidden City are painted with red paint, and there is iron in the red dye. After years of oxidation, three-sevenths of iron ions were produced. This kind of iron ion is magnetic and can produce magnetic memory effect, so when it thunders, the images of maids will be recorded.

The place where emperors and concubines lived as eunuchs. More than a century ago, it was very lively. Now, it is also very lively here. However, more than a century ago, the noise here was another kind of noise. Now, it welcomes groups of tourists every day. But many people are still afraid of the miracle of 1992.

1992, the Palace Museum witnessed the miracle of maids in thunderstorm weather. Indeed, it was photographed by many tourists. After obtaining favorable evidence, experts gave a scientific explanation (there is a scientific basis to explain the Palace Museum's meeting with maids), because the walls are red and contain iron oxide, and lightning can conduct current.

If a maid-in-waiting happens to pass by, then the palace wall is equivalent to the function of a video tape. If there is a lightning coincidence in the future, the shadow of the recorded maid-in-waiting may appear like a video projection, but it is still incredible.

There are also examples of ancient architectural miracles abroad. According to reports, when traveling at special nights such as thunder and lightning, it will be preserved by some materials, and then the same environment will appear, and the film will be shown in the same way. There are so many treasures in the Forbidden City that they may have been recorded unintentionally for some time.

This is why the image of a maid-in-waiting appears on the walls of the Forbidden City. It's not apparate, it's not Machamp's paranormal phenomenon.