Casimir Effect


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From the perspective of modern physics vacuum is not emptiness. Quantum theory showed that a vacuum is an extremely dynamic, continuously changing substance, something like boiling liquid from the virtual - born and then dying - elementary particles. In other words, a vacuum in terms of quantum theory are not just "nothing", may be regarded as a sea of so-called zero hesitation, and even if in the space of no real particles and no real quantum - photons, electric and magnetic fields have zero fluctuations (the same can be said about the other quantum fields). And now it turns out that fluctuations in the vacuum zero very clearly shown itself in a number of remarkable physical effects, one of which was predicted in 1948 by Dutch physicist Hendrik Kazimierz and his name is. In recent years the Casimir effect area unusually Annexes expanded to cover almost all physics - the theory of intermolecular interactions to particle physics and cosmology. We describe the most impressive challenges, where the effect was to play a particularly prominent role.
In 1948, Casimir considered two flat metal neutral - uncharged - plates, located in a vacuum parallel to each other at some distance. Since the electric field does not penetrate deep into the metal, electrical component zero hesitation, directed along the plates, should vanish. And consequently, spoke Casimir, vacuum sea duty to undergo certain distortions, as though his energy was endless, and will remain such. Yet, as first observed Casimir, if this infinity deduct from the source (before making plates), the ultimate get some energy, concluded between the plates. This energy is negative, and hence (according to the rules of mechanics), should lead to the plate will be attracted to each other. Unusual attraction of such force, called the vacuum, is that it is not used by any of the masses, nor of the charges, nor from others of similar standing, called constants physicists regard, and is determined solely by the distance between the plates. Such a force, from the perspective of many theorists of the time, looked unlikely any exotic, but after 10 years in 1958, attracted kazimir was discovered experimentally, in full accordance with the theory predictions.
Initially there was a mad idea Casimir try to explain the action of vacuum electron stability mysterious forces. Indeed, the electron has the electric charge, and his repulsive different parts of each other. Do not vacuum forces impede its collapse? Attractive idea, however, "failed" - kazimir energy sphere has been positive, corresponding to the forces of repulsion, not attraction. (It subsequently emerged that the role of the Casimir effect in the physics of elementary particles was far more sophisticated.)
Vacuum energy and forces are not only in limited quantities, but in the topologically neevklid spaces, that is, those that can not be translated into Euclidean mutually unequivocal and ongoing transformation. For example, the unlimited plane Casimir no effect, on the surface of a sphere is. That is why the Casimir effect, as it turned out, is of direct relevance to the question, is finite or infinite universe - one of the most intriguing in the history of mankind. Science of the universe as a whole - modern cosmology - based on Einstein's general theory of relativity and allowed three possibilities.
If the average density of matter in the universe less than the critical value 10-92 g/cm3, the space like the surface of our world hyperboloid rotation, if the average density is critical, we live in an ordinary flat space. Incidentally, it is precisely this possibility seems to be the most preferable in terms of the currently popular models of inflationary universe. If the average exceeds a critical density, the universe likened to the surface of the space sphere and its volume is finite. It would seem that the issue of sacramental universe limbs eventually receive a clear answer. However, the situation is not easy.
Indeed, the average density of matter known to only a very approximate, and its values differ slightly from critical, and even unclear, upwards or downwards. Moreover, as some philosophers emphasize dealing with the question of infinity, observational data on the average density is always reluctant to include the final volume, and therefore, relying only on them, in principle can not be concluded infinity universe. Thus, these philosophers argue, the issue falls outside the scope of physics and must be based on philosophical considerations.
Here's something to protect the competence of the cosmological physics and made the Casimir effect. In fact, if we live in a flat or hyperbolic world, the Casimir effect not, and if in a spherical, it should manifest itself. Relevant positive vacuum energy density is very small, but in principle it can be recorded in the local measurements on them and reconstruct the structure of the universe as a whole - in particular, to solve the problem of limbs - indefinitely. Casimir effect, as recently revealed, plays an important role in other issues of cosmology, for example, when discussing mechanisms for inflation or, say, the cosmological "time machine" I. Novikov and K. Thorne.
For more than ten years the Casimir effect theorists are discussing about the problem of the structure of hadrons, that is strongly interacting particles. As part of the theory of strong interactions - Quantum Chromodynamics - hadrons can be simplistically represent as bubbles in a vacuum (the so-called "bags"), which concluded within the quarks and gluons. Zero fluctuations quantized fields of quarks and gluons lead to the emergence of energy kazimir bag, which, as it turned out, is about ten percent of their total energy. The contribution of energy Casimir should also take into account when determining the radius of the bag, mass hadron and its other characteristics, measured in the experiment.
Another interesting application Casimir effect refers to the multidimensional model type Kaluza - Klein. Under such models, "real" dimension of our space-time more than four, say, 10, 11 or 26. However, extra measurements (except for our four-three spatial and time) or short-circuit, as they say, movement at very short distances - the order of 10-33 cm, so we simply do not notice them. Here is this something extra closure measurements and guarantees the Casimir effect.
Finally, the Casimir force have been extremely sensitive to the parameters of hypothetical light or even massless particles, predicted today in a single gauge theories of supersymmetry and supergravity (scalar aksion, dilaton, arion, antigraviton spin unit and many others). Such particles can not be detected with the help of even the most powerful accelerator, because they are neutral and able to permeate the huge column of matter, almost not interacting with them. But it is these particles lead to the emergence of new slowly decreasing with distance - long-range - forces that can record against the backdrop of the Casimir force. Such work conducted at Moscow State University under the leadership of Doctor of Sciences VI Panova using atomic force microscope. It is possible therefore that in the near future Casimir effect will be a new test to predict the fundamental physical theories.