Author Topic: Quantum Physics: What is and what it does?  (Read 2865 times)

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Quantum Physics: What is and what it does?
« on: August 07, 2011, 04:44:22 AM »
It's been one hundred years that Planck had to resort to an unusual expression to explain the results of measurements of intensity of radiation emitted by an ideal radiator - black body - thus causing him to establish the value of a new universal constant that was known as Planck's constant. From then on, and also because of other experiences that had equally impressive results in the context of Newtonian mechanics and Maxwell's electromagnetism, researchers at the beginning of last century were forced to make assumptions that led to the revolutionary development of a new physically able to describe the strange phenomena occurring at the atomic scale, quantum mechanics. A quantum system, unlike the classic, can only be described by the possible alternatives (not necessarily two) that our assembly to present it.

The wave associated with the system carries the possibility of interference between the different alternatives and is the maximum information that we have on the system in question. The application of this theory to problems in atomic scales and sub-atomic presents results as the quantization of energy or quantum tunneling which, in itself, since the establishment of a merit another article that the reader could appreciate more interesting los.

O is that quantum mechanics describes successfully the behavior of matter from high energy (particle physics) to the energy scale of chemical reactions, or even biological systems. The thermodynamic behavior of macroscopic bodies, under certain conditions, also requires the use of quantum mechanics. The question that remains is then, why do not observe these phenomena in our daily lives, ie, macroscopic objects? Well, there are two reasons for this.

The first is that Planck's constant is extremely small compared with the macroscopic quantities that have their same size. Based on this fact, we can infer that the effects due to its non-null value, will become increasingly noticeable as we increase the size of the systems. Second, there is the effect known as decoherence.

This effect has only recently begun to be studied and the fact is we can not separate a macroscopic body from the environment where it is. Thus, the medium will have a decisive influence on the dynamics of the system so that the necessary conditions for the maintenance of quantum effects disappear in a time scale very curta.Entretanto, new technologies in the manipulation of physical systems or even micro scales nanoscopic allow us to make devices that exhibit quantum effects involving, collectively, an enormous number of particles.

In these systems the decoherence, though not gone, his influence has somewhat reduced, which allows us to observe quantum effects for some time. An important application for some of these devices is the construction of quantum processors, which would make our computers even faster. In this situation, minimizing the effects of decoherence is highly desirable because, otherwise, these processors would differ from anything clássicos.

Como processors can see, it seems that quantum mechanics is the correct theory to describe physical phenomena at any scale energy. The macroscopic universe was only a particular case for which there is a more efficient way of description, Newtonian mechanics. This can be obtained as a special case of quantum mechanics but the converse is not true.

Many authors, because they feel comfortable with so-called orthodox or Copenhagen interpretation of quantum mechanics, try to create alternative theories to replace it. However, it should be noted that, despite its weirdness, quantum mechanics did not show any failure since it was developed in the 20s, which do not provide experimental evidence that points to where to look for issues that can tear it down.

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