Summary of Key Points
Recently, a TV program featuring "Great Chinese Craftsmen" demonstrated a skill where an iron block was attached to a heavy object, and there were rumors that the surface had been polished to a precision of 5 nanometers by hand. This article clarifies several misconceptions through scientific explanations: The attachment of the iron block was achieved using van der Waals forces between atoms (or with the help of additional materials), and the so-called "5-nanometer polishing" referred to the surface roughness, not precision. The craftsman's statement that "there are no ordinary rulers available for measurement" meant that the rulers he used were not suitable for such tasks (although industrial facilities have high-precision measuring tools). At the same time, the article acknowledges the value of traditional craftsmanship while also highlighting the advancement of modern technology.
1. Iron Block Attached to a Heavy Object: Not "Magic," but Science and Skill
In the program, two iron blocks were able to stick together and lift a weight of 520 kilograms. This was not due to them being perfectly flat, but rather because they fit together tightly and the atoms between them exerted van der Waals forces.
- Principle: When two metals are ground against each other for long enough, their surfaces become closely fitted. In a vacuum, the distance between atoms can be reduced to within 1 nanometer, generating weak van der Waals forces that allow them to stick together.
- Technical Detail: Iron oxidizes quickly in air, forming an oxide layer that prevents atomic bonding. Therefore, the craftsmen likely used nano-silver paste, which breaks down the oxide layer and helps the metals adhere. If lead or gold (which do not oxidize easily) were used, they would have stuck together without any additional material. In short, this was a demonstration of scientific principles, not pure manual magic.
2. "5-Nanometer Polishing by Hand": A Misunderstanding by the Host
The claim that the surface was polished to 5 nanometers by hand was a misunderstanding:
- The craftsman did not mention a precision of 5 nanometers; it was probably a misheard statement or an exaggeration by the host. A more likely explanation is that the surface roughness was around 5 nanometers.
- What is Surface Roughness? It refers to the average depth of the microscopic bumps on a surface. For example, a concrete floor has a roughness of about 0.1 millimeters, a glass mirror has less than 20 nanometers, and astronomical telescope lenses can achieve less than 0.2 nanometers. Polishing to a roughness of 5 nanometers means that the average depth of the surface's bumps is only 5 nanometers. This can be achieved with fine polishing compounds (although modern techniques can achieve even lower roughness levels). Therefore, "hand-polishing to 5 nanometers" does not mean creating objects with a size of 5 nanometers; it simply means making the surface extremely smooth. This skill is impressive but not some impossible miracle.
3. "No Rulers Available for Measurement": Refers to Ordinary Rulers, but Industrial Tools Exist
The craftsman mentioned that there were no ordinary rulers suitable for his measurements (e.g., straightedges or calipers with a maximum precision of 10 micrometers). However, industrial facilities use high-precision measurement methods such as laser interference technology, which can measure displacements with nanometer or even picometer accuracy (1 picometer = one-thousandth of a nanometer). For example, the mirrors in EUV lithography machines and the mirrors of the Webb Telescope are measured using this technique.
- Extreme Example: The LIGO gravitational wave detector can detect displacements as small as one ten-thousandth of a proton's diameter (about 10^-20 meters, or one billionth of a nanometer).
4. Traditional Craftsmanship vs. Modern Technology: Complementary, Not Competitive
Both traditional polishing techniques and modern technology have their value:
- Advantages of Traditional Craftsmanship: Certain complex shapes or special materials require skilled craftsmanship and intuition, which machines may not be able to replicate. For example, in the aerospace industry, manual polishing might be more suitable for producing unique parts.
- Advantages of Modern Technology: Higher precision (e.g., ion beam polishing can achieve a roughness of 0.1 nanometers) and faster efficiency, making it ideal for mass production.
Conclusion
The craftsmanship demonstrated by the "Great Chinese Craftsmen" is indeed impressive, but misunderstandings and exaggerations in the media created a sense of deception among viewers. The scientific principles behind these techniques are real, and traditional skills should be respected. However, we must also acknowledge the advancements in modern technology. We should applaud the craftsmanship while maintaining a rational understanding of technological developments and avoid being misled by exaggerated claims.