Why are there so many mirror videos on TikTok?

In 1919, the famous Austrian neurologist and founder of psychoanalysis Sigmund Freud published an essay titled The Uncanny, dedicated to what would become one of the most influential aesthetic concepts of the twentieth century. Freud defined the “uncanny” as that unsettling feeling that arises when something deeply familiar suddenly becomes strange. A typical situation where this effect manifests is, for example, the encounter with identical twins—a circumstance that, in some cases, can provoke a sense of estrangement and unease. From this perspective, mirrors are also considered “uncanny” objects. This quality of mirrors, along with the fascination they generate, has recently resurfaced in a TikTok trend that is hard to explain to those unfamiliar with the language of social networks: it involves placing a towel in front of a mirror, hiding behind it, and then showing—through a side shot—that the body's reflection is still visible. The same trick is done using a sheet of paper and any object. The question that many creators and users then ask, fueling public curiosity with ironic and astonished tones, is how the mirror “knows” what’s behind the towel or paper. To understand the principle behind the trend, it is useful to start with a fundamental concept: all objects—including mirrors—reflect light. Think, for example, of a blue T-shirt: when light hits it, the fabric absorbs almost all components of the light spectrum, except for the blue light, which is reflected and reaches our eyes, making us perceive that particular color.

Mirrors, unlike other things, are specially designed to reflect most of the light rays that hit them. This is possible thanks to the materials they are made of, such as aluminum or more commonly silver—among the best natural reflectors. When light hits a reflective surface like a mirror, it always behaves the same way: it bounces off at the same angle. In other words, if a ray of light with a certain angle hits a mirror, it is reflected with an equal angle in the opposite direction. This physical law is called the Law of Reflection. This explains why, in the mirror-themed TikTok trend, the subject hidden behind the towel is only visible from a certain angle: the light rays that hit the person’s body bounce off the mirror and reach the camera lens only when the shot is taken from the side. If, instead, the mirror is viewed frontally, those same rays do not reach the viewer, and the hidden figure remains invisible.

The Popularity of Science on Social Media

This type of content is part of a broader phenomenon in which science communication is increasingly finding space on social networks, capturing the attention of a wide and often young audience. In recent years, part of traditional scientific outreach has undergone a profound transformation, adapting to new digital languages to become more accessible, engaging, and in many cases, viral. In this context, platforms like the Italian Geopop have evolved from being simple educational pages to being considered actual media outlets. On platforms like TikTok, Instagram, and YouTube, relatively complex scientific topics—like the workings of mirrors—are increasingly being explored using simple language, often accompanied by small experiments, creative metaphors, or ironic formats. As science becomes part of the typical entertainment on social media, it seems to be shedding its elitist image and becoming more accessible to the general public.