Our eyes and sense of touch can differentiate between various objects based on the surface texture. There are surfaces that are rough, whereas others have a smooth feel. We are especially appreciative of smooth surfaces, possibly because only a select few have such qualities. Smooth surfaces may also be indicative of superior quality such as shiny apples and tomatoes, glass, marble, etc. Smooth surfaces also reflect more light, which makes them naturally attractive.
Our inclination to smooth surfaces makes us wonder which is the smoothest surface in the world. Is the smoothest surface man-made or occurs naturally in nature? For better understanding, let us take a look at some of the smoothest surfaces in the world.
Atom Mirror – The smoothest surface in the world is referred to as the ‘quantum stabilized atom mirror’. Scientists have created this in a laboratory environment. The base of the atom mirror comprises silicon crystals measuring 50 microns in thickness. On top, there is a layer of lead measuring 1 to 2 nanometers thick. Helium atoms are used to measure the reflective properties of the atom mirror. In terms of practical use, an atom mirror can be utilized for making advanced electronic microscopes.
Atomically flat crystal surfaces – These are created layer by layer in a laboratory environment. Enhanced smoothness is achieved via chemical etching and annealing processes.
Graphene – This is a single layer of carbon atoms, positioned as a hexagonal lattice in two-dimensional design. Graphene is considered as one of the smoothest surfaces in the world. Graphene is also conductive and very strong. This is why it has potential for use in various fields such as drug delivery, flexible displays, precise sensors, anti-corrosive paints and coatings, wide range of electronic goods and faster DNA sequencing.
Synthetic Quartz Crystal – This is grown in a laboratory environment via the process of hydrothermal synthesis. These crystals are used for making various high-precision products such as optical filters, wavelength plates, crystal oscillators, etc. Synthetic quartz crystals are also regularly used in a wide variety of scientific experiments.
Silicon Spheres – This was created as part of the International Avogadro Project. One of the key objectives was to determine the Avogadro constant (NA). It essentially seeks to link mass to the number of atoms or molecules in a substance. For this, uniform crystals of silicon-28 were used to create spheres of mass of 1 kg. The silicon spheres thus created are considered to have one of the smoothest surfaces in the world.
While there are quite a few examples of smoothest surfaces in the world, creating a perfectly smooth surface may not be possible with current technology. At the atomic level, there are uncertainties of quantum mechanics. Moreover, one also has to deal with thermal vibrations at very small scales. However, researchers continue to experiment with the goal to create a perfectly smooth surface.