Because the image is inverted along the horizontal axis. In fact, the mirror is neither upside down nor upside down, but upside down. When moving in the I direction, the mirror image also moves in the I direction, which shows that the mirror image follows every movement in reality as long as it moves in the direction parallel to the mirror plane. However, when moving in the J direction, the mirror image moves in the opposite direction, which indicates that the mirror image is inverted along the axis perpendicular to the mirror surface. In a word, when looking in the mirror, the left and right, up and down are actually not opposite, but "front" and "back"

In fact, if you think that the left and right are upside down, it is also the conclusion that you have not reversed the front and back, and there is no upside down. If the left and right are not reversed by default, it is reversed. So you can understand the problem as what's the difference between up, down, left and right. From a mathematical point of view, there is no difference between them, but there is a difference in people's consciousness. The mirror only reflects the mirror image truthfully, neither upside down nor left and right upside down. It is people's cognition of objective facts that has reversed. The reason for wrong cognition is that people confuse the cognitive angle, because the inertia of thinking is at work and they regard their own mirror image as a part of themselves; ? Instead of treating a person as a real objective reality, we should understand that mirror image is also a real objective reality. In this way, we won't think that what is formed in the mirror is fictional.

Parity is not conserved, and the mirror image of the brain will not be reversed. This shows that consciousness may be a weak interaction. If parity is conserved, we may be in the mirror without knowing it. Whether the main argument is conservative or not determines the relationship between human subjective time and the direction of thermodynamic time arrow. The current theory denies people's subjective time arrow. In other words, people can be divided into left and right sides, but they can't tell the order. In other words, post-80s may be younger than post-90s. No wonder I feel young. When facing the mirror, the people in the mirror have not changed their left and right hands, but their hearts are still facing left, just because they are upside down, which leads to the eyes growing to the back of the head and the back of the head becoming the front face.