Cerebral cortical discharge
There is also a medical explanation for this phenomenon, that is, the instantaneous discharge of cerebral cortex, or false vision, or visual memory, which often occurs in a very familiar environment. Our brain has a memory cache. When you see something or encounter something, you first store the memory and then cache it. The reason why what happened in front of us seems to have experienced this feeling is because we made a mistake in memory storage and put it in historical memory. When you look at what happened in front of you, you find it out from the historical memory, and you feel as if it had happened before. This illusion is more likely to occur when the brain is tired.
Temporal and spatial disorder
Time and space disorder: for example, you need a tool, but you can't find it anywhere in the house, but after a while or a while, the tool is clearly where it is usually placed. From Einstein's point of view, there are many time and space in this world, and each time and space runs according to general laws. They are parallel, generally have no intersection, but have a time sequence, but there are exceptions. When time and space intersect, that is, time and space are out of order. This is the case when tools disappear, such as a pair of pliers, and suddenly appear in the original place. In other words, the pliers temporarily turned around in other time and space, this time just to let you meet. Of course, such coincidences are still rare. So do people. If it happens that your present time and space intersect with your future time and space, that is to say, you have entered the future time and space for a short time and come back soon. If you repair your bike with pliers in the future time and space, you will do the same thing when you return to the present time and space, but you have stored it in your memory, so you feel that this scene seems to have been experienced somewhere. This has nothing to do with age and other experiences.