What is the principle behind the magical “re-icing phenomenon”?

Science Fiction Network, January 5 (Jin Kaiyi) Put a copper wire on an ice cube and tie weights on both sides of the wire. What do you think will happen? The ice cube is cut in half by the copper wire? But the interesting thing is that the copper wire actually scratches into the ice cube, and there is no scratch on the surface of the ice cube. What is going on?

This interesting experiment is called the "refreezing phenomenon". When a piece of ice is compressed on one surface, the pressure lowers the melting point, causing the ice to melt into water. Once the pressure is removed, the melting point rises back to its original level, and the water freezes back into ice.

In 1859, British physicist Faraday first discovered this phenomenon. The occurrence of re-icing is closely related to the crystal structure of ice. The crystal molecules in the ice are arranged more densely. When the ice feels pressure, the arrangement of the crystal molecules will change from order to disorder, and the gaps will begin to become smaller. As the pressure increases, the melting point of ice decreases, so the copper wire will be scratched into the ice. After the copper wire passes, the ice is no longer under pressure and the melting point returns to normal. Because the copper wire is very thin, the melted ice will condense in a very short time.

This phenomenon may seem magical, but it is actually very common in life. For example, when it snows, you pick up a pile of snow with your hands and apply pressure on it to melt it. When you let go, the water condenses again and becomes a snowball. When you skate on an ice rink, the ice under the skates melts into water as the skates slide across the ice. The moment the skates leave the ice, the melted ice can quickly refreeze, so the ice surface remains smooth and intact without any grooves.

However, the repair of ice scratches also depends on the specific temperature and humidity of the air at that time. When the temperature is relatively high, the scratches will be repaired faster; when the temperature is very low, the scratches will disappear more slowly. Deeper scratches will take a long time, and when the surrounding ice surface is in a semi-molten state again, the scratches will slowly disappear due to the effect of gravity.