After the Spring Festival holiday, many people took high-speed trains to bid farewell to their hometowns and return to their cities of work. Recently, the topic of "Don't stick the smartwatch dial on the high-speed train window" has sparked a heated discussion online. Many netizens warn everyone not to try easily. However, driven by curiosity, some people still cannot resist verifying. As expected, the smartwatch is firmly attached to the high-speed train window glass and cannot be removed. So, why can the smartwatch dial be so firmly attached to the high-speed train window? How to remove a watch that has been sucked in? The reporter recently interviewed Li Yitan, a researcher at the National Colloidal Materials Engineering Technology Research Center of Shandong University, regarding this matter. To explain why the smartwatch dial is firmly attached to the car window glass, we need to first introduce a physical phenomenon - the glue phenomenon. Li Yitan introduced that the phenomenon of light glue refers to the phenomenon where when the surfaces of two objects in contact are smooth to a certain extent, the smoother the surface, the greater the frictional force between the two. This phenomenon seems to contradict common sense in daily life. People generally believe that the smoother the surface of an object, the lower the frictional force, and the rougher the surface, the greater the frictional force Li Yitan introduced that the phenomenon of light glue requires certain conditions: the surfaces of two objects must be smooth enough, and the molecules on the surfaces of the objects must be close enough. When these two conditions are met, the intermolecular interaction force, known as van der Waals force, will tightly pull the two together. In addition, the surface of the smartwatch dial and high-speed rail window glass cannot be absolutely smooth, for example, there may be bubble areas formed due to improper film application on the watch dial. At this point, when the dial is close to the car window glass, the gas in the bubble zone will be expelled, creating a low pressure or even approaching a vacuum state in that area. At this point, under the action of atmospheric pressure, the smartwatch will be tightly pressed against the surface of the car window glass. Netizens think that smartwatches are 'sucked', but in fact they are 'pressed' Li Yitan introduced that there are many similar things. For example, people use a straw to drink water, and the reason why they can suck out water is that by inhaling, the pressure of the straw in the mouth is lower than the external atmospheric pressure, and then the water is "pressed" into the mouth by atmospheric pressure. What should we do if the smartwatch is firmly attached to the glass and cannot be removed? The reporter saw online that many netizens use methods such as hard pulling and prying. But these methods can damage the watch dial and high-speed rail glass. Directly prying open is definitely not advisable. This kind of hard hitting method often yields twice the result and half the effort Li Yitan said that the key to solving the problem is to reduce the contact area between the two objects on the one hand, and to reduce the pressure difference between the dial and the glass and the outside world on the other hand. He suggested that the surfaces of two objects can be slightly deformed by twisting the smartwatch, thereby reducing the contact area between the two; You can also try to gently insert tools such as fine needles or thin cards into the gap between the smartwatch dial and glass, allowing air to enter and balancing the air pressure between the dial and glass with the external air pressure. In addition, you can also try heating your smartwatch Li Yitan introduced that on the one hand, heating can cause the glass and watch dial to fluctuate due to different degrees of expansion, thereby reducing the contact area; On the other hand, heating will cause the small bubbles formed by the dial film to expand, just like inflating a tire to increase air pressure, making the fit between the two less tight and achieving the effect of separating them. But at the same time, Li Yitan also reminded: "If netizens choose the heating method, they must remember to operate slowly and choose the appropriate temperature to avoid damaging the smartwatch