August 14, 2012 11:32
Recently, a group of American physicists could construct a so-called "chip time" — the structure, the possibility of which was predicted long ago. Crystal feature is the ability to periodically become asymmetrical, not only in space but also in time. Therefore, it is possible to make out a high-precision chronometer.
Crystals — generally quite paradoxical education. Take, for their relationship with the symmetry: as we know, the crystal itself, judging by his appearance, can be seen as simply a model of spatial symmetry. However, the crystallization process is nothing like her willful violation.
This is a very good example illustrates the formation of crystals in solution, for example, kakih-nibud salts. If we analyze this process from the beginning, it will be seen that in the solution, the particles are chaotic, and the whole system is at a minimum energy level. However, the interactions between particles are symmetric with respect to rotations and translations. However, after the liquid crystallized, there is a condition in which both these symmetries are violated.
Thus, we can conclude that the interaction between the particles in the resulting crystal is not symmetrical. From this follows a number of important properties of the crystals — for example, the structures, as opposed to a liquid or gas, a different conduct electricity or heat in different directions (can hold to the north and to the south — no). In physics, this property is called anisotropy. This crystalline anisotropy has long been used by man in various industries, such as electronics.
Another interesting property of crystals is that he, as the system is always at the minimum energy level. What is most interesting, it is much lower than, for example, the solution to "breed" the crystal. We can say that in order to get the data structures necessary to "take" the energy from the source substrate.
Thus, the formation of the crystal is lowering the energy level of the system and the breakdown of the initial spatial symmetry. Not long ago, two physicists from the United States, Al Shapiro and Frank Wilczek (by the way, the Nobel laureate), think about whether the existence of so-called "four-dimensional" crystal, where symmetry breaking occurs not only in space but also in time.
Using complex mathematical calculations, the researchers were able to show that this is possible. The result was a system that exists as a real crystal, the lowest energy level. But the interesting thing is that it is due to the formation of certain periodic structures are not in space but in time would come to an asymmetric final state. The authors call this system very solemnly — "crystal of time."
After a while a group of experimental physicists led by Professor Xiang Zhang of the University of California (USA) has decided to establish such a system is not only on paper but in reality. Scientists have created a cloud of beryllium ions, then "locked" it in a circular electromagnetic field. Since electrostatic repulsion equally charged ions of each other makes them evenly distributed in a circle, the researchers, in fact, got gas crystal. And while the characteristics of the field were the same, then the system will, in theory, are not supposed to change.
At the same time, calculations, and later observations have shown that this is the ion ring is not fixed. Gaseous crystal constantly rotated, and the interaction of ions with it were balanced, it is not. All this occurred even when the crystal is cooled to near absolute zero. Thus, the structure is actually a "crystal-time": it has the properties of the frequency and asymmetry, both in space and in time.
Curiously, the slowly rotating ring ions, designed the group of Professor Zhang has caused many lay association with perpetual motion. Of course, the gas crystal looks like a perpetum mobile, but in reality it is not. After all, this system can not perform any work, since all its components are on the same energy level (in addition, a minimum). And according to the second law of thermodynamics, the work is only possible in the system, the components of which are at least two energy levels.
At the same time, this does not mean that the "crystal of time" can not be used for practical purposes. Professor Zhang believes that based on it can be constructed, for example, a high-precision chronometer. After the transition from symmetry to asymmetry has a clear frequency. In the meantime, the professor and his colleagues want to do a more detailed study of the properties they have created a wonderful structure …